GALDERMA 1 BASIC SCIENCE

Question 1

What component in the epidermis is responsible for maintaining a barrier to water loss in the stratum corneum?

Answer 1

Odland bodies, also known as lamellar granules, keratinosomes, and membrane-coating granules, are small organelles that are discharged from granular cells into the intracellular space of the granular layer of the epidermis. These bodies have two known functions: they mediate stratum corneum cell cohesion and they form a barrier to water loss. Odland bodies are round to oval, measure approximately 300 to 500 nm in diameter, and possess a trilaminar membrane and a laminated interior. They contain neutral sugars linked to lipids and/or proteins, hydrolytic enzymes, and free sterols.

Filaggrin is a breakdown product of filaggrin precursor, a component of keratohyaline granules, which aggregates with keratin filaments and acts as a “glue” for keratin filaments.

Involucrin is a cysteine-rich protein synthesized in the cytoplasm of spinous cells.

The enzyme, transglutaminase, cross-links involucrin in the granular layer forming an insoluble cell boundary that is resistant to denaturing and reducing chemicals.

Loricrin, is a highly insoluble sulfur- and glycine/serine-rich protein, which is the major protein comprising the cornified cell envelope.

Question 2

Which type of collagen in mutated in osteogenesis imperfecta?

What are the functions of collagens I, II, III, IV, VII?

Answer 2

Collagen type I is mutated in osteogenesis imperfecta. The COL1A2 gene is located on 7q22 and the COL1A1 is on 17q22. The other listed collagens are not involved in osteogenesis imperfecta.

Collagen II is in cartilage and vitreous,

Collagen III is in fetal skin, blood vessels and intestines,

Collagen IV is in basement membranes

Collagen VII in anchoring fibrils and amnion.

Question 3

In the epidermis, the cell most responsible for antigen detection and processing is the ____.

This cell is the central pathogenesis of what 4 conditions?

Answer 3

The Langerhans cell is a bone narrow-derived, antigen-presenting cell found in all layers of the epidermis, oral mucosa, esophagus, and vagina.

Langerhans cells ingest and process antigens, mature, migrate to a local lymph node, and then present the antigen to a na�ve (or resting) T cell, activating that T cell.

The Langerhans cell is central to the pathogenesis: Atopic dermatitis

Psoriasis

Allergic contact dermatitis

Leishmaniasis, certain infections

Question 4

Which element is necessary for function of matrix metalloproteinases?

Answer 4

Zinc
Matrix metalloproteinases are required for normal tissue architecture and normal turnover of the extracellular matric. All of them have zinc at the active site and require octahedral binding of calcium ions to maintain structural integrity.

Question 5

Which of the following statement about glomus cells is correct?

1. Tumors of glomus cells are most commonly found on the tongue
   2 Are of neural origin
   3 Allow rapid shunting of blood from the arterioles to venules, bypassing capillaries
   4 Tumors composed of glomus cells are asymptomatic
   5 Tumors composed of glomus cells are often malignant

Answer 5

Tumors composed of glomus cells are usually PAINFUL**, not asymptomatic. The are derived from **Suquet-Hoyer canals** and allow rapid shunting of blood from the arterioles to venules. Glomus cells are part of glomus tumors which are most often solitary, purple dermal nodules on the extremities. Most often, they are seen on the **fingers and toes. They are usually painful and rarely malignant. As opposed to a glomus tumor, glomangiomas are usually painless. They also most often occur on extremities, but can also occur on the trunk.

Question 6

What structure delineates the anatomic region between the nail bed and the distal groove, where the nail plate detaches of the distal portion of the digit?

1 Nail matrix
2 Proximal nail fold
3 Lunula
4 Eponychium
5 Hyponychium

Answer 6

The hyponychium is the structure that delineates the anatomic region between the nail bed and the distal groove, where the nail plate detaches of the distal portion of the digit. The corneal layer of the hyponychium accumulates in part under the free margin of the nail plate. In most cases, the hyponychium is covered by the distal nail plate, however, it may become visible in the case of nail biters.

Question 7

Which of the following groups of adhesion proteins are found in both the hemidesomsome-anchoring filament complexes and lamina densa?

1 Plectin
2 Heparin sulfate proteoglycan
3 Laminin 5
4 Nidogen
5 Type VII collagen

Answer 7

Laminin 5 is found both in the hemidesomsome-anchoring filament complexes and lamina densa. Plectin is found in the hemidesomsome-anchoring filament complexes. Heparin sulfate proteoglycan is found only in the lamina densa, collagen VII in the sublamina densa, and nidogen in the lamina densa.

Question 8

Which of the following groups of adhesion proteins are found in both the hemidesomsome-anchoring filament complexes and lamina densa?

1 Plectin
2 Heparin sulfate proteoglycan
3 Laminin 5
4 Nidogen
5 Type VII collagen

Answer 8

Laminin 5 is found both in the hemidesomsome-anchoring filament complexes and lamina densa. Plectin is found in the hemidesomsome-anchoring filament complexes. Heparin sulfate proteoglycan is found only in the lamina densa, collagen VII in the sublamina densa, and nidogen in the lamina densa.

Question 9

Each of the following is true about melanosomes except:

1 Most characteristic organelle of the melanocyte
2 Tyrosinase activity decreases as melanosomoes mature
3 Are transferred to keratinocytes via phagocytosis
4 Are singly dispersed in the basal layer in white skin
5 Are larger in size in black skin compared to white skin

Answer 9

4 Are singly dispersed in the basal layer in white skin

Several differences exist that may explain the heterogeneity of skin color. The number of melanocytes are the same; however, there are several differences in the melanosomes. Differences in skin color can be attributed to five factors. In racially heavily pigmented skin, (1) there is greater production of melanosomes in melanocytes, (2) individual melanosomes show a higher degree of melanization, (3) melanosomes are larger, (4) the melanosomes are dispersed to a greater degree in the keratinocytes, and (5) there is a slower rate of degradation.

Question 10

What is the major function of urocanic acid?

1 Bacteriocidal acid produced by stratum corneum
2 Primarily a UVB filter
3 Primarily a UVA filter
4 Helps degrade free fatty acids
5 Aids in protecting the skin from dermatophytes

Answer 10

Primarily a UVA filter
Urocanic acid a by product of filaggrin degradation and has a peak absorbtion of 345 nm. It serves as a major UVA filter.

Question 11

Which of the following options is characteristic of integrins?

1 Defects in the alpha-6 domain of integrin result in epidermolysis bullosa simplex with muscular dystrophy
2 Alpha-6-Beta-4 integrin is found at sites where desmogleins attach
3 Expression is seen in all layers of the epidermis
4 The extracellular alpha6 domain binds collagen 7
5 These proteins coordinate linkage between intermediate filaments and extracellular matrix of the basement membrane

Answer 11

These proteins coordinate linkage between intermediate filaments and extracellular matrix of the basement membrane

Defects in the BETA-4 (not alpha-6) domain of integrin result in junctional epidermolysis bullosa with pyloric atresia. Its expression is seen in the basal cell layer and binds to laminins.

Question 12

Desmosine and isodesmosine are typical amino acids found in:
1 Collagen fibers
2 Anchoring fibril
3 Elastic fibers
4 Heparan sulfate
5 Anchoring plaques

Answer 12

Desmosine and isodesmosine are typical amino acids found in elastic fibers. They crosslink fibrillin. Anchoring fibrils are composed of collagen VII and collagen fibers and have the most typical amino acids of proline and hydroxyproline. Heparan sulfate do not typically contain these amino acids.

Question 13

The epidermis is comprised of what type of cells?
1 Keratinocytes, Melanocytes, Merkel cells, Langerhan cells
2 Keratinocytes, Endothelial cells, Merkel cells, Langerhan cells
3 Keratinocytes, Melanocytes, Neutrophils, Langerhan cells
4 Keratinocytes, Melanocytes, Merkel cells, Goblet cells
5 Keratinocytes, Endothelial cells, Merkel cells, Goblet cells

Answer 13

The adult epidermis is composed of three basic cell types: Keratinocytes, melanocytes, and Langerhans cells. An additional cell, the Merkel cell, can be found in the basal layer of the palms and soles, the oral and genital mucosa, the nail bed, and the follicular infundibula.

Question 14

Telogen effluvium:
1 Involves a diffuse alopecia affecting more than 50% of the scalp
2 Often results from antimetabolites used during cancer chemotherapy
3 Is an inflammatory alopecia devoid of scarring
4 Is a patchy alopecia affecting less than 50% of the scalp
5 Results from sudden illness or surgery

Answer 14

Results from sudden illness or surgery
Telogen effluvium is an excessive loss of club hairs from the normal resting follicles of the scalp. The follicle is pushed from anagen to catagen to telogen. There is no inflammatory process involved. Causes of telogen effluvium are illness, surgery, parturition, fever, drugs, traction, starvation, and hypervitaminosis A. Usually, the hair loss only involves less than 50% of the scalp. There is no specific therapy, and most cases are self-resolving within months.

Question 15

When do melanocytes begin to synthesize melanin?
1 2nd month of gestation
2 3rd month of gestation
3 4th month of gestation
4 5th month of gestation
5 6th month of gestation

Answer 15

Melanocytes begin to synthesize melanin in the 3rd month of gestation.

Question 16

What is the average duration of the telogen cycle in terminal scalp hair?
1 2-6 years
2 2-3 weeks
3 3 months
4 6 months
5 9 months

Answer 16

The average duration of the telogen phase of the hair cycle is 3 months; this feature explains why telogen effluvium is typically observed 3 months following a traumatic event or serious illness. The average duration of the anagen phase of the hair cycle is 2-6 years, whereas that of the catagen cycle is 2-3 weeks.

Question 17

Which of the following is not a specialized type of sebaceous gland?
1 Moll’s gland
2 Meibomian gland
3 Gland of Zeis
4 Montgomery’s tubercle
5 Fordyce spot

Answer 17

Moll’s gland
There are several types of specialized sebaceous glands that are not associated with a hair follicle. They include Montgomery’s areolar tubercle, Fordyce spots of the lip, Glands of Zeis of the cutaneous eyelid, and Meibomian glands of the eyelid. Moll’s gland of the eyelid are a modified apocrine gland.

Question 18

Which protein is the largest component of the cornified cell envelope?
1 Keratin
2 Involucrin
3 Profilaggrin
4 Loricrin
5 Ceramide

Answer 18

Loricrin
The cornified cell envelope is a durable, protein-lipid polymer that eventually acts as a mechanical and chemical barrier on the exterior of cornified cells. In the upper spinous layer, keratohyaline granules release profilagrin and loricrin. Profilaggrin is cleaved to filaggrin and subsequently aggregates keratin filaments. Loricrin is the major protein component of the cornified cell envelope and is bound to the cell membrane by transglutaminases (in addition to other structural proteins like involucrin, keratins, elafin, cystatin A and desmosomal peptides). This forms the highly insoluble proteinaceous component of the cornified cell envelope.

Question 19

Which sebaceous gland is located on the areola?
1 Montgomery’s tubercles
2 Tyson’s glands
3 Zeis glands
4 Meibomian glands
5 Fordyce’s spots

Answer 19

Montgomery’s tubercles
Montgomery’s tubercles are sebaceous glands not associated with hair follicles present on the areola. Tyson’s glands on the labia minora and glans, meibomina and Zeis glands are present on the eyelids , and Fordyce’s spots are located on the buccal

Question 20

Which of the following statements about darkly pigmented races versus lighter pigmented races is correct?
1 The number of melanosomes in melanocytes are the same
2 The individual melanosomes have the same degree of melanization
3 The melanosomes are equal in size melanosomes
4 There are equal numbers of melanocytes
5 There is a faster rate of melanosome degradation

Answer 20

There are equal numbers of melanocytes
Individuals with darker pigmentation have an equal ratio of melanoyctes to keratinocytes. Darker pigmentation is related to an increased number of melanosomes, increased melanization, greater size of melanosomes, and slower degradation.

Question 21

Which of the following domains is targeted by the autoantibodies in bullous pemphigoid?
1 NC16A of BP180
2 Laminin 5
3 Plectin
4 alpha-6 integrin
5 NC16A of BP230

Answer 21

NC16A of BP180
The NC16A domain of BP180 is the target of autoantibodies in bullous pemphigoid. It interacts with alpha-6 integrin extracellularly.

Question 22

Which of the following polypeptides is found in the lamina lucida?
1 plakoglobin
2 desmoplakin
3 keratocalmin
4 demoyokin
5 laminin 5

Answer 22

laminin 5
Laminin-5 is a basement membrane extracellular matrix protein that mediates attachment substrate for both adhesion and migration in a wide variety of cell types, including epithelial cells, fibroblasts, neurons and leukocytes and is a preferred adhesion substrate for epithelial cells (Koshikawa et al., 2001). The remaining listed items are part of the desmosomal plaque in the epidermis.

Question 23

Which of the following make up the major protein of the cornified cell envelope?
1 Loricrin
2 Involucrin
3 Envoplakin
4 Filaggrin
5 Laminin V

Answer 23

Loricrin
Loricrin is the major protein component of the cornified cell envelope (CE). Involucrin is cross-linked by transglutaminase in the granular layer to form an insoluble cell boundary. Envoplakin may link the CE to desmosomes and to keratin filaments. Filaggrin is thought to promote aggregation and disulfide bonding of keratin filaments in CE. It is degraded into urocanic acid and pyrrolidone carboxylic acid. Both of which hydrate the stratum corneum and block UV radiation. Laminin V is found in the basement membrane and is not involved in the formation of the cornified cell envelope.

Question 24

Eccrine glands are found in all the following areas of the body except:
1 Axillae
2 Palms
3 Labia minora
4 Scalp
5 Cutaneous lip

Answer 24

Labia minora
Eccrine glands are sweat glands enervated by cholinergic sympathetic nerves mediated by acetylcholine. They absent on modified skin which lacks appendages like the vermillion border, nail beds, glans penis, inner aspect of the prepuce and the labia minora.

Question 25

Which of the following amino acids are typically found in elastic fibers?
1 Desmosine
2 Isoleucine
3 Proline
4 Hydroxyproline
5 Glycine

Answer 25

Desmosine
Desmosine and isodesmosine are typical amino acids found in elastic fibers. Glycine, proline and hydroxyproline are found as components of collagen. Isoleucine is not specific for elastin fibers.

Question 26

Nikolsky sign can be seen when:
1 When an intact epidermis shears away from the underlying dermis, leaving a moist surface
2 Spreading bulla phenomenon with pressure on an intact bulla
3 Swollen, itchy and or red after stroking the skin
4 Central depression within a lesion when squeezed along its margins
5 Disappearance of color when the lesion is pressed

Answer 26

When an intact epidermis shears away from the underlying dermis, leaving a moist surface

Nikolsky sign can be seen when an intact epidermis shears away from the underlying dermis, leaving a moist surface (seen in pemphigus vulgaris, staphylococcus scalded skin syndrome (SSSS), and toxic epidermal necrosis). Spreading bulla phenomenon with pressure on an intact bulla is referred to as Asboe-Hansen sign, commonly seen with pemphigus vulgaris. Swollen, itchy and or red after stroking the skin is referred to Darier’s sign and can be seen in systemic mastocytosis or urticaria pigmentosa. Central depression within a lesion when squeezed is referred to as the dimpling sign and is seen in dermatofibromas. Disappearance of color or blanching when the lesion is pressed is commonly found on vascular lesions

Question 27

Which signaling molecule mediates the transition of hair cycling from telogen to anagen phase?
1 Foxn1
2 Fgf5
3 Sonic hedgehog
4 Dihydotestosterone
5 5a-reductase

Answer 27

Sonic hedgehog
 Sonic hedgehog (Shh), a signaling molecule secreted by ectodermal cells of the developing hair follicle, appears to be critical in mediating the transition from telogen to anagen during postnatal hair cycling

Question 28

Which of the following stains would you expect to be positive in a normal eccrine unit?
1 S-100
2 Prussian blue
3 Giemsa
4 Verhoeff von Gieson
5 Steiner

Answer 28

S-100
Eccrine glands stain S-100 and CEA positive. The remaining stains would not be expected to stain normal eccrine sweat glands. Prussian blue (Perl�s) is an iron stain which stains iron or hemosiderin bright blue. Giemsa stains mast cell granules purple (heparin in the granules) and can also be useful in staining in Leishmaniasis. Verhoeff von Gieson is a stain for elastic tissue that stains blue-black. Steiner stain is a silver stin for spirochetes similar to a Warthin Starry or Dieterle stain.

Question 29

People with darker skin show:
1 Smaller, more concentrated melanosomes
2 A more rapid degradation of melanosomes
3 A lessened production of melanosomes within melanocytes
4 A higher degree of dispersion of melanosomes in keratinocytes
5 A grouping of melanosomes with a low degree of melanization

Answer 29

A higher degree of dispersion of melanosomes in keratinocytes

More darkly pigmented races show a greater production of melanosomes in the melanocyte, melanosomes with a higher degree of melanization, larger melanosomes, a higher degree of dispersion of melanosomes in the keratinocytes, and a slower rate of melanosome degradation.

Question 30

Which eponym describes vestigial lines of pigmentary demarcation?
1 Fuchter lines
2 Wallace’s lines
3 Langer’s lines
4 Lines of Blaschko
5 Dermatome

Answer 30

Fuchter lines
Fuchter lines are vestigial lines in which the dorsal surface has more melanocytes than ventral surface. Wallace’s lines are the well-demarcated lines around the margin of the foot and hand.

Question 31

Which cadherin is responsible for adhesion of Langerhan cells to the epidermis?
1 E-cadherin
2 P-cadherin
3 N-cadherin
4 Desmoglein
5 Desmocollin

Answer 31

E-cadherin
E-cadherin is responsible for the adhesion of Langerhan cells to the epidermis. There are two major subclasses of cadherins which mediate cell adhesion and play a fundamental role in normal development, classic (E-,P-,N-cadherin) and desmosomal (desmoglein and desmocollin). They depend on calcium for their function.

Question 32

The major component of the anchoring filaments is:
1 Uncein
2 Plectin
3 a6b4 integrin
4 Laminin 5
5 Collagen type IV

Answer 32

Laminin 5

Anchoring filaments exist within the lamina lucida. They are primarily comprised of laminin 5 and BP180. Laminin 5 is a cross-shaped assembly of 3 classes of polypeptides, a, b, g. The anchoring filaments function as a structural network to which other proteins attach, and they function as signaling molecules that transmit morphogenetic information to transmembrane proteins of the basal cell layer (such as the integrins). Laminin 5 is also called epiligrin and binds to the a6b4 integrin at the hemidesmosome.

Question 33

The formation of granulation tissue depends on the presence of:
1 Neutrophils
2 Fibronectin
3 Collagen type I
4 Platelets
5 Collagen type IV

Answer 33

Fibronectin
Granulation tissue forms approximately four days after injury. It is composed of new capillaries, macrophages, fibroblasts, and blood vessels. The formation is dependent on the presence of fibronectin. There tends to be an ordered sequence of matrix deposition. Fibronectin is deposited first followed by collagen 3 and then collagen 1. Granulation tissue primarily contains type 3 collagen.

Question 34

Elastic fibers are present in the dermis and are responsible for providing tissue resiliency. They are comprised of elastin as well as microfibrillar proteins including:
1 Fibrillins and fibulins
2 Hyaluronic acid
3 Collagen II
4 Laminin 5 and BPAG2
5 Desmoplakin and plakoglobin

Answer 34

Fibrillins and fibulins

Elastic fibers are comprised of elastin as well as microfibrillar proteins including fibrillins and fibulins. Hyaluronic acid is a glycosaminoglycan found in the extracellular matrix of the dermis. Collagen II is the predominant collagen found in cartilage. Laminin 5 and BPAG2 are important anchoring filaments in the basement membrane zone. Desmoplakin and plakoblobin are proteins found in the anchoring plaques of desmosomes in the epidermis.

Question 35

Which of the following medications is concentrated in the eccrine glands?
1 Cyclophosphamide
2 Cytarabine
3 Ciprofloxacin
4 Cephalexin
5 All of the answers are correct

Answer 35

All of the answers are correct
The above listed drugs, as well as beta-lactam antibiotics, antifungals such as ketoconazole and griseofulvin, are known to be secreted into eccrine sweat ducts. This feature may explain the development of neutrophilic eccrine hidradenitis and eccrine squamous syringometaplasia in the context of chemotherapy.

Question 36

Glomus cells are:
1 Modified fibroblasts
2 Modified skeletal muscle cells
3 Vascular smooth muscle cells
4 Monocytes
5 Neuronal cells

Answer 36

Vascular smooth muscle cells
Glomus cells are derived from Suquet-Hoyer canals. They are vascular smooth muscle cells that allow the rapid shunting of blood from the arterioral to venular system, bypassing the capillaries. This process occurs primarily on the palms and soles.

Question 37

The cutaneous immunofluorescence pattern in patients with Senear-Usher syndrome is:
1 Intercellular IgG and C3
2 Linear IgG and C3 along the basement membrane zone
3 Intercellular IgG on guinea pig esophagus
4 Intercellular IgG and C3 and linear IgG and C3 along the basement membrane zone
5 Linear IgG and C3 along the basement membrane zone and intercellular IgG on guinea pig esophagus

Answer 37

Intercellular IgG and C3 and linear IgG and C3 along the basement membrane zone

Senear-Usher syndrome, or pemphigus erythematosus, is a variant of pemphigus foliaceus characterized by crusted papules and plaques with a seborrheic distribution (malar region, scalp, upper chest and back). They demonstrate in-vivo IgG and C3 deposition on keratinocyte cell membranes and the basement membrane zone, in addition to circulating anti-nuclear antibodies.

Question 38

Which of the following cells are required for wound healing?
1 Neutrophil
2 Macrophage
3 Eosinophil
4 Langerhans cell
5 Lymphocyte

Answer 38

Macrophage
The macrophage is required for wound healing. The macrophages debride tissue, secrete collagenase and stimulate expression of FGF, IL-1, TGF-beta, PDGF and TGF-alpha thus facilitating transition from inflammation to repair.

Question 39

Red or blonde hair pigmentation primarily results from:
1 The presence of eumelanin
2 The absence of melanin
3 The presence of pheomelanin
4 The reduced activity of tyrosinase
5 The reduced activity of DOPA dehydroxylase

Answer 39

The presence of pheomelanin

Hair color is determined by melanocytes. The melanocytic activity of follicular melanocytes is coupled to anagen � hair is only pigmented when it is growing. Pigment is produced in the matrix area of follicle, above the follicular papilla. Eumelanin is the pigment of brown/black hairs, and pheomelanin is the pigment of red/blonde hairs. Intensity of color is proportional to the amount of pigment. The absence of pigment produces white hair, and markedly reduced pigment produces gray hair.

Question 40

Aprocrine glands are adnexal glands that are quiescent until puberty. Once active, they secrete their contents by what mechanism?
1 Vacuolar exocytosis
2 Passive diffusion
3 Decapitation secretion
4 Autocrine secretion
5 Holocrine secretion

Answer 40

Decapitation secretion
Apocrine glands are adnexal glands that are quiescent until puberty. They are found in the axillae, the anogenital region, mammary glands, Moll’s gland of the eyelid, and ceruminous glands of the external auditory meatus. They develop from the upper bulge of the hair follicle during embryology. Once active, apocrine glands secrete their contents by means of decapitation secretion. During this process the apical portion of the gland pinches off and enters the lumen of the gland.

Question 41

Which of the following statements is true about eccrine glands?
1 Postganglionic sympathetic fibers with acetylcholine as the principal neurotransmitter
2 Postganglionic sympathetic fibers with norepinephrine as the principal neurotransmitter
3 Postganglionic parasympathetic fibers with acetylcholine as the principal neurotransmitter
4 Postganglionic parasympathetic fibers with norepinephrine as the principal neurotransmitter
5 Postganglionic sympathetic fibers with both norepinephrine and acetylcholine as the principal neurotransmitters

Answer 41

Postganglionic sympathetic fibers with acetylcholine as the principal neurotransmitter

Eccrine glands are innervated by postganglionic sympathetic fibers with acetylcholine as the principal neurotransmitter. This explains why medications associated with anticholinergic side effects may be associated with hypohidrosis.

Question 43

Granulation tissue primarily contains:
1 Collagen I
2 Collagen III
3 Collagen IV
4 Fibrin
5 Collagen VII

Answer 43

Collagen III
Granulation tissue begins to form four days after injury and is composed of new capillaries, macrophages, fibroblasts, blood vessels and primarily collagen type III. Formulation of granulation tissue is dependent on the presence of fibronectin and progresses through an orderly sequence of matrix deposition: fibronectin to collagen III then finally collagen I.

Question 44

Dimple sign refers to:
1 When an intact epidermis shears away from the underlying dermis, leaving a moist surface
2 Spreading bulla phenomenon with pressure on an intact bulla
3 Swollen, itchy and or red after stroking the skin
4 Central depression within a lesion when squeezed along its margins
5 Disappearance of color when the lesion is pressed

Answer 44

Central depression within a lesion when squeezed along its margins

Central depression within a lesion when squeezed is referred to as the dimpling sign and is seen in dermatofibromas. Nikolsky sign can be seen when an intact epidermis shears away from the underlying dermis, leaving a moist surface (seen in pemphigus vulgaris, staphylococcus scalded skin syndrome (SSSS), and toxic epidermal necrosis). Spreading bulla phenomenon with pressure on an intact bulla is referred to as Asboe-Hansen sign, commonly seen with pemphigus vulgaris. Swollen, itchy and or red after stroking the skin is referred to Darier’s sign and can be seen in systemic mastocytosis or urticaria pigmentosa. Disappearance of color or blanching when the lesion is pressed is commonly found on vascular lesions

Question 45

Which cytokeratin would you expect to be preferentially expressed in the keratinocytes of a psoriatic plaque:
1 K1
2 K5
3 K12
4 K15
5 K16

Answer 45

K16
K16 and K6 act as markers for hyperproliferative keratinocytes. They are found in skin disease such as psoriasis, warts, actinic keratoses, and SCC’s.

Question 46

Asboe-Hansen Sign refers to:
1 When an intact epidermis shears away from the underlying dermis, leaving a moist surface
2 Spreading bulla phenomenon with pressure on an intact bulla
3 Swollen, itchy and or red after stroking the skin
4 Central depression within a lesion when squeezed along its margins
5 Disappearance of color when the lesion is pressed

Answer 46

Spreading bulla phenomenon with pressure on an intact bulla

Spreading bulla phenomenon with pressure on an intact bulla is referred to as Asboe-Hansen sign, commonly seen with pemphigus vulgaris. Nikolsky sign can be seen when an intact epidermis shears away from the underlying dermis, leaving a moist surface (seen in pemphigus vulgaris, staphylococcus scalded skin syndrome (SSSS), and toxic epidermal necrosis). Swollen, itchy and or red after stroking the skin is referred to Darier’s sign and can be seen in systemic mastocytosis or urticaria pigmentosa. Central depression within a lesion when squeezed is referred to as the dimpling sign and is seen in dermatofibromas. Disappearance of color or blanching when the lesion is pressed is commonly found on vascular lesions

Question 47

Which epidermal layer do pilar cysts generally not have a:
1 Stratum corneum
2 Stratum granulosum
3 Stratum spinosum
4 Stratum basale
5 Stratum lucidum

Answer 47

Stratum granulosum
Pilar cysts do not have a granular layer, they do have all the other layers.

Question 48

Apocrine chromhidrosis results from which of the following contents of apocrine sweat?
1 Lipofuschin
2 Squalene
3 Cholesterol
4 Fatty acids
5 Ammonia

Answer 48

Lipofuschin
Chromhidrosis refers to the secretion of pigmented sweat, most commonly yellow, green or black. It reflects the rich lipofuschin content of apocrine sweat. Extrinsic apocrine chromhidrosis results from staining of sweat and garments by chromogenic bacteria, such as Corynebacterium spp.

Question 49

Human sebum is distinguished from lipids of internal organs by the presence of:
1 Cholestrol
2 Cholestrol esters
3 Squalene
4 Wax esters
5 Glycerides

Answer 49

Wax esters
As human sebum exits the sebaceous gland, its major constituents are squalene, cholesterol, cholesterol esters, triglycerides, and wax esters. With passage through the hair follicle, triyglycerides in the sebum become hydrolyzed by bacterial enzymes, so that by the time the sebum reaches the skin surface, it contains free fatty acids, mono- and diglycerides in addition to the original components. Human sebum is distinguished by the presence of wax esters and squalene. The lipids of human internal organs contain no wax esters and little squalene. The squalene that is produced in internal organs is quickly converted to lanosterol and then to cholesterol, so it does not remain in its original form. Human sebaceous glands do not convert squalene to sterols.

Question 50

Type VII collagen in found in anchoring fibrils and also in:
1 Fetal skin
2 Bone
3 Amnion
4 Aorta
5 Blood vessels

Answer 50

Amnion
Type VII collagen is present in anchoring fibrils and amnion. Fetal skin and blood vessels contain type III collagen. The aorta contains type VI collagen. Bone contains type I collagen.

Question 51

Which of the following statements about elastic fibers is true?
1 Elastic fibers form 35% of the dry weight of the skin
2 Elastic fibers are 90% elastin wrapped in fibrillin
3 Collagen 1 is mutated in Marfan syndrome
4 Oxytalan fibers run parallel within the superficial papillary dermis
5 Elaunin fibers run perpendicular in thin bands within the reticular dermis

Answer 51

Elastic fibers are 90% elastin wrapped in fibrillin
Elastic fibers are responsible for much of the elasticity of the dermis. They are essentially 90% elastin wrapped in fibrillin. They form 4% of the dry weight of the skin. Fibrillin 1 is mutated in Marfan syndrome. Oxytalan fibers run PERPENDICULAR from the DEJ within the superficial papillary dermis. Elaunin fibers run parallell in thin bands within the reticular dermis.

Question 52

Which of the following is the most common genetic alteration seen in mucosal melanomas?
1 GNAQ
2 Cyclin Dependant Kinase 4/6
3 BRAF
4 KIT
5 HDM2

Answer 52

KIT
Mucosal melanomas tend to have an activating mutation in KIT. GNAQ mutations are seen in both uveal melanomas and blue nevi. Cyclin dependant kinase 4/6 binds cyclin D and together phosphorylate Retinoblastoma. HDM2 targets p53 for ubiquitination.

Question 53

What component is the major barrier in the stratum corneum?
1 Sebum
2 Squalene
3 Collagen
4 Ceramide
5 Triglycerides

Answer 53

Ceramide
The major component of lamellar granules of the keratinocytes is ceramide. These play a major role in the barrier function of the skin.

Question 54

Which of the following skin conditions involves elastin?
1 Rothmund-Thompson
2 Epidermolytic Hyperkeratosis
3 Pseudoxanthoma elasticum
4 Progeria
5 Classic type Ehlers-Danlos syndrome

Answer 54

Pseudoxanthoma elasticum
There are many genodermatoses that involve elastin. Pseudoxanthoma elasticum shows increased glycosaminoglycans on elastic fibers, calcium deposition and accumulation of fragmented and calcified elastic fibers. Cutis laxa shows decreased desmosine and lysyl oxidase. In Marfan sydrome there is decreased fibrillin I and fragmentation of elastic fibers. Buschke-Ollendorf syndroms shows increased desmosine and increased amount of thickend elastic fibers. Other elastin disease are congenital contractural arachnodactyly from a mutation in fibrillin II and anetoderma which shows decreased desmosine and loss/fragmentation of elastic fibers. Classic type Ehlers-Danlos syndrome is caused by a defect in collagen V and not in elastin. Progeria is caused by a defect in lamin A. EHK is caused by a defect in keratin 1/10. Rothmund Thompson is caused by a defect in RecQL4, a helicase gene.

Question 55

Which of the following skin conditions involves elastin?
1 Rothmund-Thompson
2 Epidermolytic Hyperkeratosis
3 Pseudoxanthoma elasticum
4 Progeria
5 Classic type Ehlers-Danlos syndrome

Answer 55

Pseudoxanthoma elasticum
There are many genodermatoses that involve elastin. Pseudoxanthoma elasticum shows increased glycosaminoglycans on elastic fibers, calcium deposition and accumulation of fragmented and calcified elastic fibers. Cutis laxa shows decreased desmosine and lysyl oxidase. In Marfan sydrome there is decreased fibrillin I and fragmentation of elastic fibers. Buschke-Ollendorf syndroms shows increased desmosine and increased amount of thickend elastic fibers. Other elastin disease are congenital contractural arachnodactyly from a mutation in fibrillin II and anetoderma which shows decreased desmosine and loss/fragmentation of elastic fibers. Classic type Ehlers-Danlos syndrome is caused by a defect in collagen V and not in elastin. Progeria is caused by a defect in lamin A. EHK is caused by a defect in keratin 1/10. Rothmund Thompson is caused by a defect in RecQL4, a helicase gene.

Question 56

The first cell type to migrate into a new wound in great numbers is the:
1 Neutrophil
2 Monocyte
3 Macrophage
4 Lymphocyte
5 Mast cell

Answer 56

Neutrophil
Neutrophils migrate with monocytes concurrently, but arrive first in great numbers because of their abundance in circulation. Chemoattractants for the PMNs are fibrinogen, fibrin split products, C5a and leukotrienes. If wound contamination is controlled, PMN migration ceases within a few days and they become entrapped within the wound clot, undergo apoptosis or are phagocytosed by macrophages.

Question 57

At any one time, the approximate proportion of hair follicles in anagen is:
1 40%
2 60%
3 85%
4 95%
5 15%

Answer 57

85%
Most hair follicles are in anagen, and thus most hair follicles involve growing hair. The longer a hair follicle is anagen, the longer the hair can grow in length. Hairs of the scalp grow approximately 0.4 mm per day, and thus the date of your next hair cut can be accurately calculated.

Question 58

Which of the following elements is necessary for melanin production?

1 Copper 2 Selenium 3 Iron 4 Zinc 5 Calcium

Answer 58

Copper
Melanin is synthesized from tyrosine vis the action of the enzyme tyrosinase (tyrosine to DOPA to DOPAquinone to melanin). Tyrosinase is a copper containing enzyme. The other elements are not specifically required for melanin synthesis.

Question 59

All mononuclear phagocytic cells in the dermis express:
1 CD3
2 CD6
3 CD34
4 CD68
5 CD20

Answer 59

CD6
CD6 and CD11c are expressed on all mononuclear phagocytic cells in the dermis. CD3 is a T-cell marker and CD20 is a B-cell marker. CD34 is expressed on mast cells and CD68 on macrophages.

Question 60

Embryologically, epidermal stratification occurs at approximately what estimated gestational age?
1 4 weeks
2 8 weeks
3 12 weeks
4 16 weeks
5 20 weeks

Answer 60

8 weeks
Epidermal stratification begins at about 8 weeks estimated gestational age and is completed by the 2nd trimester. Epideral stratification occurs when an ‘intermediate layer’ develops between the epidermal basal cells and the overlying layer of periderm cells. The periderm is an embryonic structure that covers the primitive epidermis until keratinization begins, at which point the periderm sloughs off and contributes to the protective covering of the newborn, the vernix caseosa. This intermediate layer is highly proliferative, such that by 24-25 weeks estimated gestaional age, the epidermis consists of 4 or 5 layers, in addition to the degenerating periderm.

Question 61

During a salt split skin test, if the location of the deposition if found on the roof (lamina lucida), which of the following could be a diagnosis?
1 Bullous pemphigoid
2 Anti-epiligrin cicatricial pemphigoid
3 Epidermolysis bullosa acquisita
4 Bullous eruption of lupus erythematosus
5 Bullous eruption of tinea

Answer 61

Bullous pemphigoid
Bullous pemphigoid is one of the many bullous diseases that may be found on the ‘roof’ of the blister, the others include pemphigoid gestationis, linear IgA bullous dermatosis, cicatricial pemphigoid. The other answer (except for bullous tinea, in which a salt split would not be performed) are those found on the ‘floor’ of the blister (lamina densa).

Question 62

Epidermolysis bullosa simplex (EBS), Weber Cockayne type, is caused by what defect?
1 Collagen VII
2 Alpha-6-beta-4 integrin
3 Keratins 1 & 10
4 Keratins 5
5 Plectin

Answer 62

Keratins 5
All subtypes of EBS are caused by a defect in keratins 5 & 14 except EBS with muscular dystrophy which is caused by a defect in plectin. An alpha-6-beta-4 integrin defect is seen in junctional epidermolysis bullosa (JEB) with pyloric atresia. Collagen VII defect is seen in EB aquisita (EBA), Bart’s syndrome and dominant EB (DEB). Keratin 1 & 10 defects are not seen in any of the EB subtypes.

Question 63

The major protein component of the cornified envelope is:
1 Envoplakin
2 Desmoplakin
3 Plectin
4 Loricrin
5 Transglutaminase

Answer 63

Loricrin
Loricrin is the major component of the cornified envelope (CE). The proteins of the CE are synthesized in the spinous and granular layers. The CE is primarily a protein/lipid polymer formed within the differentiating layer of keratinocytes. The CE eventually exists outside of the cornified cells after the granular cell undergoes a programmed destruction (apoptosis). Self-destructing granular cells are called transition cells.

Question 64

Anchoring fibrils are primarily composed of:
1 Type I collagen
2 Type III collagen
3 Type IV collagen
4 Type VII collagen
5 Type II collagen

Answer 64

Type VII collagen
Anchoring fibrils are found in the sublamina densa and are made up of collagen type VII. This collagen type is mutated in dystrophic epidermolysis bullosa, and targeted in epidermolysis bullosa acquisita and bullous lupus erythematosus.

Question 65

The main collagen component of the basement membrane is:
1 Collagen IV
2 Collagen III
3 Collagen I
4 Tenascin-X
5 Collagen VII

Answer 65

Collagen IV
Collagen IV is the main collagen component of basement membranes. Collagen I is the main collagen of mature dermis, bone and tendon. Collagen III is found in fetal skin, blood vessels and intestines. Tenascin-X is mutated in some forms of Ehlers-Danlos syndrome and is not associated with the basement membrane. Collagen VII makes up anchoring fibrils and amnion

Question 66

Which of the following statements about plectin is correct?
1 Links fillagrin to the plasma membrane
2 Crosslinks proteins in adherens junction
3 Mutations result in junctional epidermolysis bullosa with pyloric atresia
4 Plectin is a member of the plakin family
5 Plectin is a constituent protein of the desmosomal plaque

Answer 66

Plectin is a member of the plakin family
Plectin is a hemidesmosomal protein and is not present in the desmosome. It links intermediate filaments to the plasma membrane, crosslinks hemidesmosomal proteins, mutations result in epidermolysis bullosa simplex with muscular dystrophy and is a member of the plakin family.

Question 67

Each of the following is true about the basement membrane zone except:
1 Anchoring filaments attach the basal cell membrane to the lamin lucida
2 Can be visualized on light microscopy with PAS staining
3 Lamina densa is composed of type IV collagen
4 Contains laminin 1 and laminin 5
5 Anchoring fibrils are composed of type VII collagen

Answer 67

Anchoring filaments attach the basal cell membrane to the lamin lucida
The basement membrane zone is seen on staining with PAS stain. It appears as a homogenous band approximately 1 micron thick at the dermo-epidermal junction. The hemidesmosomal complex and basement membrane zone play an integral role in maintaining cellular adhesion. Anchoring filaments (primarily composed of laminin 5 and BPAG2) attach the basal cell membrane to the lamina densa NOT lamina lucida.

Question 68

Pick the correctly paired keratin with its structure:
1 K1/K10 - basal cells
2 K3/K12 - esophagus
3 K4/K13 - cornea
4 K5/K14 - suprabasal cells
5 K16/K6 - palms and soles

Answer 68

K16/K6 - palms and soles
Keratin 1 and 10 are found in the stratum spinosum. K5 and K14 are found in the basal layer. K3 and K12 are found in the suprabasilar cells of the cornea. K4 and K13 are found in the non-cornifying cells of stratified mucosa. K16 and K6 are found in the palms and soles.

Question 69

The mechanism of action of ipilimumab can be described as
1 Inhibitor of CTLA-4
2 Antibody to CD27
3 Fusion protein binding B7
4 Antibody to CD 8 T cell
5 Inhibitor of CD27

Answer 69

Inhibitor of CTLA-4
Ipilimumab is an antibody to CTLA-4, this interaction causes inhibition of CTLA-4 which normally inhibits T cell co-activation by binding to B7 (which normally binds to CD28).

Question 70

Which of the following statements about the direct immunofluorescence pattern in lichen planus is correct?
1 The DIF is negative in the vast majority of cases
2 Deposition of IgG is within cytoid bodies in the superficial dermis
3 The DEJ deposition is granular
4 Deposition of fibrinogen is within cytoid bodies in the deep dermis
5 There is prominent deposition of IgM within the spinous layer of the epidermis.

Answer 70

The DEJ deposition is granular
The DEJ deposition is granular. The DIF is positive in the vast majority of cases. Deposition of IgM and fibrinogen is within cytoid bodies in the superficial dermis. There is no deposition of IgM within the spinous layer of the epidermis.

Question 71

Once a keratinocyte leaves the basal cell layer, the normal transit time to stratum corneum is at least:
1 7 days
2 14 days
3 21 days
4 28 days
5 35 days

Answer 71

14 days
Once a basal cell leaves the basal layer in humans, normal transit time to stratum corneum is at least 14 days. Transit time through the stratum corneum to desquamation requires 14 more days.

Question 72

The finding on DIF that reflects binding of the Ro and La antigens in subacute cutaneous lupus erythematosus is:
1 Granular fluorescence throughout the cytoplasm and nucleus of basal keratinocytes
2 Cytoid bodies
3 Immune deposits along the DE junction
4 Granular deposits along the basement membrane
5 A “chicken-wire” pattern within the epidermis

Answer 72

Granular fluorescence throughout the cytoplasm and nucleus of basal keratinocytes
Granular fluorescence throughout the cytoplasm and nucleus of basal keratinocytes reflect the binding of Ro and La antigens and is unique to SCLE. Cytoid bodies and Immune deposits along dermal-epidermal junction are seen in both DLE and SCLE. Granular deposits along the basement membrane are seen in dermatitis herpetiformis and a chicken-wire pattern of staining is seen in pemphigus vulgaris.

Question 73

The embryonic periderm becomes part of the
1 vernix caseosa
2 stratum corneum
3 stratum basale
4 dermis
5 hair follicle

Answer 73

vernix caseosa
During the second trimester of fetal development, the periderm is sloughed from most of the skin surface revealing the underlaying epidermis. The periderm becomes part of the protective coating, vernix caseosa, together with the shed lanugo, sebum and other amniotic fluid materials. Bolognia p.38

Question 74

Moving from internally to externally choose the correct description of the hair follicle:
1 Inner root sheath cuticle - Huxley’s layer - Henle’s layer - medulla - cortex - hair shaft cuticle
2 Hair shaft cuticle - cortex - medulla - Henle’s layer - Huxley’s layer _ inner root sheath cuticle
3 Henle’s layer - Huxley’s layer - inner root sheath cuticle - hair shaft cuticle - cortex - medulla
4 Medulla _ cortex _ hair shaft cuticle _ inner root sheath cuticle _ Huxley’s layer _ Henle’s layer
5 Inner root sheath cuticle _ outer root sheath cuticle _ hair shaft cuticle _ cortex _ Huxley’s layer _ Henle’s layer

Answer 74

Medulla _ cortex _ hair shaft cuticle _ inner root sheath cuticle _ Huxley’s layer _ Henle’s layer

Question 75

Darier’s sign is described as:
1 When an intact epidermis shears away from the underlying dermis, leaving a moist surface
2 Spreading bulla phenomenon with pressure on an intact bulla
3 Swollen, itchy and or red after stroking the skin
4 Central depression within a lesion when squeezed along its margins
5 Disappearance of color when the lesion is pressed

Answer 75

Swollen, itchy and or red after stroking the skin
Swollen, itchy and or red after stroking the skin is referred to Darier’s sign and can be seen in systemic mastocytosis or urticaria pigmentosa. Nikolsky sign can be seen when an intact epidermis shears away from the underlying dermis, leaving a moist surface (seen in pemphigus vulgaris, staphylococcus scalded skin syndrome (SSSS), and toxic epidermal necrosis). Spreading bulla phenomenon with pressure on an intact bulla is referred to as Asboe-Hansen sign, commonly seen with pemphigus vulgaris. Central depression within a lesion when squeezed is referred to as the dimpling sign and is seen in dermatofibromas. Disappearance of color or blanching when the lesion is pressed is commonly found on vascular lesions

Question 76

Upon presentation of an antigen in the skin surface, a hapten forms. The first cell to take up the hapten is:
1 B cells
2 Langerhans cells
3 keratinocytes
4 T cells
5 Mast cell

Answer 76

Langerhans cells
Most of the contact allergens are low-molecular weight chemicals, which after penetrating into the skin, have to couple with host proteins to be able to act as full antigens. These are called haptens. Upon epicutaneous application to a naive host, Langerhans cells take up the hapten, process it and migrate towards the regional lymph nodes, where the anitgen is presented to the naive T cells.

Question 77

The main permeability barrier in the lamina densa is:
1 heparan sulfate proteoglycan
2 collagen IV
3 laminin 5
4 nidogen
5 alpha-6-beta-4 integrin

Answer 77

heparan sulfate proteoglycan
5 alpha-6-beta-4 integrin
All of the listed proteins are present in the lamina densa except alpha-6-beta-4 integrin, which connects the hemidesmosome to laminin 5 in the lamina lucida. The heparin sulfate proteoglycans (perlecan) are negatively charged, thus serve as a permeability barrier. The other listed proteins do not serve this function in the lamina densa. Collagen IV is the main basic basement membrane scaffold. Defects in Collagen IV have been linked to Alport�s and Goodpasture�s syndrome. Nidogen has a �dumbbell� shape and binds both laminins and collagen IV in the lamina densa.

Question 78

A specific marker of Merkel cells is:
1 Cytokeratin 10
2 Cytokeratin 15
3 Cytokeratin 20
4 Loricrin
5 Envoplakin

Answer 78

Cytokeratin 20
Cytokeratin 20 is a specific marker for the Merkel cell. Merkel cells are mechanoreceptors located at body sites requiring high tactile sensitivity. Keratinocyte deformation results in a secretion of chemokines by Merkel cells, which make synaptic connection with neurons.

Question 79

On electron microscopy, which cell demonstrates cytoplasmic projections and secretory granules?
1 Langerhans cell
2 Keratinocyte
3 Mast cell
4 Melanocyte
5 Macrophage

Answer 79

Mast cell
Electron microscopy of mast cells demonstrates large long villi at the periphery and round or oval secretory granules. Langerhans cells show a folded nucleus and rarely phagocytized melanosomes on electron microscopy. Their characteristic feature is the presence of Birbeck granules whose disk shape with one or two vesicles at either end represents a tennis raquet. Examination of melanocytes shows an absence of tonofilaments or desmosomes with characteristic melanosomes in various stages of formation. Macrophages often contain phagocytized material within phagosomes.

Question 80

Which keratins are expressed in the stratum germinativum and are present but not made de novo in the stratum spinosum?
1 K4, 13
2 K1,10
3 K2e, 10
4 K3,12
5 K5,14

Answer 80

K5,14
K5 and K14 are expressed in the stratum germinativum (basal layer) and are defective in epidermolysis bullosa simplex. They are still present in the stratum spinosum but are not made de novo in this layer. K4 and 13 are found in mucosal epithelium. K1 and 10 are expressed in suprabasal keratinocytes, K2e and 10 in the upper spinous and granular layers, and K3 and K12 in the cornea.

Question 81

Sebaceous glands are located in each of the following locations except:
1 Nipple
2 Labia minora
3 Palms
4 Eyelids
5 Buccal mucosa

Answer 81

Palms
Sebaceous glands secrete their contents in a holocrine fashion and are primarily under the influence of androgens. They secrete triglycerides, phospholipids, esterified cholesterol, waxes but not free cholesterol. They may be found in association with hair follicles or in some areas of modified skin such as the nipple/areola, labia minora, prepuce, vermilion border, and eyelids.

Question 82

Which sebaceous gland is located on the eyelids in association with eyelashes?
1 Montgomery’s tubercles
2 Tyson’s glands
3 Zeis glands
4 Meibomian glands
5 Fordyce’€™s spots

Answer 82

Zeis glands
Zeis glands are sebaceous glands associated with eyelashes. Montgomery’s tubercles are present on the areola, Tyson’s glands on the labia minora and glans, and Fordyce’s spots are located on the buccal mucosa.

Question 83

Which of the following glands is not under neural control?
1 Sebaceous glands
2 Apocrine glands
3 Eccrine glands
4 Salivary glands
5 Ceruminous glands

Answer 83

Sebaceous glands
Sebum is secreted continuously on the skin under hormonal glands. It contains squalene, cholesterol, cholesterol esters, wax, and triglycerides.

Question 84

The proteins that make up the cornified cell envelope are synthesized in the:
1 Stratum corneum
2 Stratum basale
3 Melanocytes
4 Stratum granulosum
5 Langerhans cells

Answer 84

Stratum granulosum
The proteins that make up the cornified cell envelope are synthesized in the spinous and granular cell layer. The stratum basale is not involved in production of these proteins and there is no protein synthesis in the stratum corneum. Melanocytes and Langerhans cells are components of the epidermis but are not involved in this process.

Question 85

Cutaneous warts in renal transplant recipients show increased expression of which keratin?
1 K2
2 K5
3 K9
4 K13
5 K16

Answer 85

K13
Keratins are divided into acidic (type I) and basic (type II) subtypes. Keratin 13 is a type I keratin which is expressed suprabasally in adult epithelia and is associated with terminal differentiation. Renal transplant recipients have an increased risk of developing skin cancers and multiple warts. Factors contributing to this increased risk include human papillomavirus infection, immunosuppressive therapy, and exposure to ultraviolet radiation. Increased expression of K13 has been demonstrated in high-risk papillomas in this patient population.

Question 86

Acid keratins are expressed on which of the following chromosomes?
1 12
2 17
3 9
4 16
5 3

Answer 86

17
 Acidic keratins (K10-20) are expressed from chromosome 17. Basic keratins (K1-9) are on chromosome 12. The other listed chromosomes are not involved in keratins.

Question 87

All of the following are true regarding the formation of hair except:
1 The inner root sheath keratinizes by means of trichohyalin granules
2 Henle�s layer is outside of Huxley�s layer
3 The outer root sheath is a downward extension of the epidermis
4 Huxley�s layer contains melanin
5 The hair matrix becomes the hair and the inner root sheath

Answer 87

Huxley�s layer contains melanin
The inner root sheath is composed of three layers, which are the inner root sheath cuticle, Huxley layer, Henle layer. None of these layers contain melanin. All three layer keratinize by trichohyaline granules and disintegrate when they reach the isthmus of the hair follicle.

Question 88

Regarding the stratum germinativum (basale):
1 Intermediate filaments in basal cells insert into only hemidesmosomes
2 Keratins 1 and 10 are expressed
3 Not all basal cells have the potential to divide
4 Microfilaments assist in downward movement of cells
5 Plectins regulate adhesion and initiation of differentiation.

Answer 88

Not all basal cells have the potential to divide
Not all basal cells have the potential to divide. Stem cells give rise to transient amplifying cells which give rise to the epidermal keratinocytes. Intermediate filaments in basal cells insert into desmosomes and hemidesmosomes. Keratins 5/14 are predominantly expressed. Microfilaments assist in upward movement of cells. Integrins regulate adhesion and initiation of differentiation.

Question 89

The best substrate for immunofluoresence in the dermatologic condition transmitted by the black fly is:
1 Rat bladder
2 Monkey esophagus
3 Guinea pig esophagus
4 Armadillo foot pads
5 White mouse tail

Answer 89

Guinea pig esophagus
The black fly or Simulium nigrimanum is the vector for pemphigus foliaceus. Immunofluorescence for this condition is best performed on guinea pig esophagus. Rat bladder and monkey esophagus are used for bullous pemphigoid and paraneoplastic pemphigus. Armadillo foot pads are used to culture leprosy.

Question 90

The hair follicle is the site of production or conversion of which of the following hormones?
1 All the options are correct
2 dihydrotestosterone (DHT)
3 prolactin
4 adrenocorticotropin hormone (ACTH)
5 alpha-melanocyte stimulating hormone (MSH)

Answer 90

All the options are correct
The hair follicle converts gonadal or aderenal testosterone to dihydrotestosterone locally via 5-alpha reductase. It also cleaves proopiomelanocortin to ACTH, alpha-MSH, and B-endorphin via prohormone convertase. It also secretes corticotropin releasing hormone (CRH) as well as prolactin

Question 91

Which of the following abnormalities would be present in a patient with Harlequin ichthyosis?
1 lamellar granules are uniformly absent
2 keratohyaline granules are normal in all types of harlequin fetus
3 demoyokin mutation
4 band 6 protein is absent
5 plakoglobin is abnormal

Answer 91

lamellar granules are uniformly absent
In Harlequin ichthyosis, the lamellar granules are uniformly abnormal or absent. On electron microscopy, there is no evidence of the lipid lamellae which form due to lamellar granule discharge into the region between the granular and cornified cells (Fitz v6, p493). This is suggestive of a primary defect in lipid synthesis and protein dephosphorylation resulting in faulty lamellar body formation and secretion (Bolognia, ch. 57). Harlequin fetus/ichthyosis can be divided into three types based on the microscopic appearance of the keratohyaline granules. Type I - normal, Type II - too small to be seen by light microscopy, Type III - absent keratohyaline granules. Demoyokin, band-6 protein (a plaque component) and plakoglobin are desmosomal proteins and not involved in Harlequin ichthyosis. Recently, the gene defect was localized a defect in the ABCA12 protein.

Question 92

Which of the following cytokines is secreted by adipocytes?
1 IL-2
2 Il-4
3 IL-6
4 IL-10
5 IL-12

Answer 92

IL-6
Adipocytes secrete tumor necrosis factor (TNF)α, interleukin-6 (IL-6), leptin, adiponectin, angiotensinogen, and resistin. Specifically it has been shown that IL-6 mRNA levels in human subjects are significantly greater in adipose tissue than in other tissues known to express IL-6. It is thought that circulating IL-6 levels may be higher in obese patients, contributing to the development and progression of vascular disease in this patient population.

Question 93

Anchoring filaments originate at the hemidesmosomes and insert into the:
1 Desmosome
2 Sub basal dense plate
3 Lamina lucida
4 BPAG 180
5 Lamina densa

Answer 93

Lamina densa
 Anchoring filaments (smaller than anchoring fibrils) stretch from the plasma membrane through the subbasal dense plaque and the lamina lucida to the lamina densa.

Question 94

The first primordial hair follicles form on the eyebrows, upper lip and chin at which gestational age?
1 7 weeks
2 9 weeks
3 12 weeks
4 16 weeks
5 20 weeks

Answer 94

9 weeks
The first primordial hair follicles form at 9 weeks gestation on the eyebrows, upper lip and chin. The remaining follicles develop at 4-5 months in a cephalad to caudal direction. New follicles cannot develop in adult skin.

Question 95

Dermal dendrocytes:
1 Are responsible for immediate-type hypersensitivity reactions.
2 Actively synthesize and release IgG.
3 Present antigen to na� T cells in the lymph node.
4 Are the primary cell found in a glomangioma.
5 Are the primary cell found in an angiosarcoma.

Answer 95

Present antigen to na� T cells in the lymph node.
A dermal dendrocyte is a mononuclear phagocytic cell that is a type of antigen presenting cell. It is derived from the bone marrow and found both in the papillary and upper reticular dermis. This cell is highly phagocytic and synonymous with the melanophage that has ingested pigment. Dermal dendrocytes are likely very important to the afferent limb of the immune response.

Question 96

Melanocytes are derived from:
1 Bone marrow
2 Neural crest
3 Mesodermal precursors
4 Endodermal precursors
5 Yolk sac derived

Answer 96

Neural crest
Melanocytes are derived from neural crest precursors and migrate to the epidermis, hair matrix, retinal pigment epithelium, ear (stria vascularis), leptomeninges, and mucous membranes. The other options listed are incorrect and are not involved with melanocytes.

Question 97

Which of the following keratins would most likely be expressed in the nail bed?
1 K6a/16
2 K6b/17
3 K1/9
4 K2e/10
5 K4/13

Answer 97

K6b/17
Keratins 6b & 17 are expressed in the nail bed. K6a/16 is expressed in the outer root sheath and in hyperproliferative keratinocytes, 1/9 in palmoplantar suprabasalar keratinocytes, 2e/10 in the upper spinous and granular cell layers, and 4/13 are expressed in mucosal epithelium.

Question 98

In which of the following locations would you be least likely to identify melanocytes?
1 Stria vascularis of the ear
2 Iris
3 Leptomeninges
4 Retina
5 Pericardium

Answer 98

Pericardium
Melanocytes are found in the stria vascularis of the ear, iris, leptomeninges and retina. There are no normal populations of melanocytes found in the pericardium.

Question 99

Mast cells are derived from bone marrow ____+ cells?
1 CD3
2 CD6
3 CD20
4 CD34
5 CD68

Answer 99

CD34
CD34+ cells in the bone marrow are the precursors of mast cells. CD3 and CD20 are T and B cell markers respectively. CD6 is found on mononuclear phagocytic cells in the dermis, CD68 is a macrophage marker.

Question 100

What is the location of the unbound corticosteroid receptor?
1 Cytoplasm
2 Nucleus
3 Mitochondria
4 Plasma membrane
5 golgi apparatus

Answer 100

Cytoplasm
Both androgen and corticosteroid receptors localize to the cytoplasm. Estrogen receptors are found in the nucleus. Progesterone receptors are distributed in both the nucleus and the cytoplasm.

Question 101

Which of the following statements about Laminins is correct?
1 Laminins span from the plasma membrane of basal keratinocytes to the lamina lucida
2 Laminins provide little structural support in the basement membrane
3 Laminins provide signaling molecules that interact with other proteins to transmit morphogenetic information to the cell’s interior
4 Laminin 5 is also called plectin
5 Laminin 5 is the only laminin found in the basement membrane

Answer 101

Laminins provide signaling molecules that interact with other proteins to transmit morphogenetic information to the cell’s interior
Laminins do transmit signals to the cell’s interior. They span from the plasma membrane of basal keratinocytes to the lamina DENSA, not lucida. Laminin 5 (also known as epiligrin) is part of a structural network in the basement membrane that also includes laminin 6.

Question 102

Sebaceous glands secrete sebum via:
1 Holocrine mechanism
2 Exocrine mechanism
3 Endocrine mechanism
4 Exostosis
5 Mecrocrine mechanism

Answer 102

Holocrine mechanism
The sebaceous lobules have basal germinative cells and central sebocytes, which gradually become more distended with lipid vacuoles until they are shed into the lumen (holocrine secretion).

Question 103

Dystrophic epidermolysis bullosa results from mutations in:
1 Collagen type I
2 Collagen type II
3 Collagen type III
4 Collagen type V
5 Collagen type VII

Answer 103

Collagen type VII
Dystrophic epidermolysis bullosa results from mutations in Type 7 collagen. Type I collagen mutations are associated with osteogenesis imperfecta. Antibodies to Type II collagen are associated with relapsing polychondritis. Mutations in type V collagen result in the classic form of Ehlers Danlos while mutations in type III collagen result in the vascular form of Ehlers Danlos.

Question 104

Which of the following protein plays a major role in wound healing?
1 Uncein
2 Fibronectin
3 Nidogen
4 Entactin
5 Band-6 protein

Answer 104

Fibronectin
Fibronectin is a key player in wound healing, initially secreted by myofibroblasts. The bed/matrix of fibronectin provides an adherent base for migration into the wound, provides scaffolding for collagen fibrils and mediates wound contraction. Band-6 protein is a constituent of the desmosomes intracellular plaque. Entactin and nidogen are synonyms and are found in the dermal-epidermal junction, binding to laminin 1s alpha chain. Uncein is associated with anchoring filaments.

Question 105

Keratinocytes in the basal layer of the epidermis attach to the basement membrane zone at hemidesmosomes via what intermediate filament molecules?
1 Keratins 1 and 10
2 Keratins 5 and 14
3 Desmogleins 1 and 3
4 Desmoplakin and Desmoglobin
5 BPAG1 and BPAG2

Answer 105

Keratins 5 and 14
Keratins 5 and 14 are intermediate filaments found in the basal layer of the epidermis that play a role in attaching basal layer keratinocytes to the basement membrane zone. Keratins 1 and 10 are found in more superficial layers of the epidermis. Desmogleins, desmoplakin, and desmoglobin are all components of desmosomes which attach keratinocytes to other surrounding keratinocytes. BPAG1 and BPAG2 are basement membrane proteins.

Question 106

Which of the following cytokines are secreted from keratinocytes?
1 IL-2
2 IL-3
3 IL-17
4 IL-22
5 IL-23

Answer 106

IL-23
IL-2 is a cytokine that primarily produced by T lymphocytes and acts on other T lymphocytes as a growth factor for both survival and differentiation. IL-3 is also produced by T lymphocytes and acts as a growth factor for cells of the myeloid lineage. IL-17 is an effector cytokine that is implicated in the pathogenesis of psoriasis and produced by Th17 cells. IL-22 is also an effector cytokine produced by T lymphocytes that contributes to epidermal acanthosis in psoriasis. All of these cytokines are not secreted from epidermal keratinocytes. IL-23, which promotes Th17 effector function, is secreted by epidermal keratinocytes and upregulated in psoriasis. The p40 subunit of IL-23 is the target of drug ustekinimab used to treat psoriasis.

Question 107

Which sebaceous gland is located on the buccal mucosa and vermilion border of the lips?
1 Montgomery’s tubercles
2 Tyson’s glands
3 Zeis glands
4 Meibomian glands
5 Fordyce’s spots

Answer 107

Fordyce’s spots
Fordyce’s spots are located on the buccal mucosa and vermilion border of the lips. Montgomery’s tubercles are present on the areola, Tyson’€™s glands on the labia minora and glans, meibomina and Zeis glands are present on the eyelids.

Question 108

1 melanocyte has contact with:
1 6 keratinocytes
2 12 keratinocytes
3 18 keratinocytes
4 30 keratinocytes
5 36 keratinocytes

Answer 108

36 keratinocytes
One melanocyte and 36 keratinocytes make up one epidermal melanin unit. This melanocytes transfers pigment to these keratinocytes.

Question 109

Which of the following is true regarding BPAg1?
1 It is pathogenic in cicatricial pemphigoid
2 It is a member of the plakin family
3 It is pathogenic in pemphigoid gestationis
4 It is not pathogenic in paraneoplastic pemphigus
5 It coprecipitates with plakoglobin

Answer 109

It is a member of the plakin family
BPAg1 is a member of the plakin family, which includes envoplakin, periplakin, desmoplakin, plectin, and BPAg1. BPAg2 is pathogenic in cicatricial pemphigoid and pemphigoid gestationis. BPAg1 is pathogenic in paraneoplastic pemphigus. Desmoglein 3 is pathogenic in pemphigus vulgaris and coprecipitates with plakoglobin.

Question 110

Regarding sebaceous glands:
1 These glands are present at birth at their adult size
2 Size of the gland is proportional to the size of the associated hair follicle
3 Are always associated with a hair follicle
4 Are found everywhere on the skin except palms and soles
5 Are unilobular glands

Answer 110

Are found everywhere on the skin except palms and soles
Sebaceous glands are found everywhere on the skin except on the palms and soles. They are multilobular, emptying into the sebaceous duct. Most sebaceous glands are associated with hair follicles, but free glands exist, especially on the lip (Fordyce spots), on the nipple/areola (Montgomery�s tubercles), Meibomian glands of the eyelids and Tyson�s glands on the genitalia. The size of the sebaceous glands are not related to the size of the associated follicle. The sebaceous gland enlarges at puberty in response to increased androgens.

Question 111

Direct immunofluorescence is of no value in the diagnosis of:
1 Neonatal LE
2 Lichen planus
3 Mixed connective tissue disease
4 SLE
5 Erythema multiforme

Answer 111

Neonatal LE
DIF is of no value in the diagnosis of scleroderma, morphea, and neonatal LE. DIF of lichen planus is positive in the vast majority, with granular DEJ deposition and IgM and fibrinogen staining within cytoid bodies in the superficial dermis. In MCTD DIF shows IgG deposits within epidermal cell nuclei, and rarely along the DEJ. In SLE, while serology is more reliable, DIF can show DEJ deposition in the lupus band test. DIF of erythema multiforme shows immunoglobulin within superficial vessel walls, DEJ, and cytoid bodies.

Question 112

Which of the following enzymes does not require copper for functioning?
1 Lysyl oxidase
2 ATP7a
3 Tyrosinase
4 Cystathione beta-synthase
5 Ferrochelatase

Answer 112

Ferrochelatase
All of the listed enzymes are copper containing or dependent except ferrochelatase. Lysyl oxidase facilitates crosslinking of fibrillin in elastic fibers. ATP7a is deficient in Menkes Kinky Hair Syndrome. Cystathione beta-synthase is defective in homocystinuria. Tyrosinase catalyzes the first 2 steps, and at least 1 subsequent step, in the conversion of tyrosine to melanin. Ferrochelatase mutation leads to excess protoporphyrin production and photosensitivity.

Question 113

The greatest density of mast cells is found in the:
1 Stratum spinosum
2 Stratum basale
3 Papillary dermis
4 Reticular dermis
5 Subcutaneous fat

Answer 113

Papillary dermis
5 Subcutaneous fat
Mast cells are found in the greatest density in the papillary dermis, in sheaths of the appendages, and around blood vessels and nerves of the subpapillary plexus. These cells are derived from CD34+ stem cells residing in the bone marrow. They produce and store in secretory granules many inflammatory mediators such as histamine, heparin, tryptase, chymase, carboxypeptidase, neutrophil chemotactic factor and eosinophilic chemotactic factor of anaphylaxis. They also release, without storing, growth factors, cytokines and leukotrienes. Giemsa or Leder stains are used to identify mast cells in biopsy specimens. Giemsa stains mast cell granules purple. Leder stains granules red.

Question 114

Elastic fibers contain the specific amino acids:
1 Lysine and proline
2 Leucine and isoleucine
3 Alanine and phenylalanine
4 Desmosine and isodesmosine
5 Glycine and proline

Answer 114

Desmosine and isodesmosine
Desmosine and isodesmosine are the typical amino acids of elastic fibers. Elastic fibers are comprised of elastin that is wrapped by fibrillin microfibrils. Elastic fibers form a complex meshwork extending from the lamina densa of the dermo-epidermo junction through the dermis. Elastic fibers return the skin to a normal shape after being stretched.

Question 115

Hair grows at:
1 0.004 mm/day
2 0.04 mm/day
3 0.4 mm/day
4 4 mm/day
5 10 mm/day

Answer 115

0.4 mm/day Hair grows at an average of 0.4 mm/day. The other options are incorrect.

Question 116

Regarding dermal-epidermal junction, which of the following statements is true:
1 There are no anchoring filaments in lamina lucida
2 Lamina fibroreticularis lies above lamina densa
3 Lamina fibroreticularis comprises of anchoring fibrils and the elastic microfibrils
4 Blood vessels cross the dermal-epidermal junction to reach the epidermis
5 Lamina lucida is an electron-dense layer

Answer 116

Lamina fibroreticularis comprises of anchoring fibrils and the elastic microfibrils
Lamina fibroreticularis comprises of anchoring fibrils and the elastic microfibrils. Lamina fibroreticularis lies below lamina densa. Blood vessels don’t cross the dermal-epidermal junction to reach the epidermis. Basement membrane contain both: 1)Lamina basale which include a.lamina lucida and b.lamina densa( which contain collagene IV & other glycoproteins like laminins,fibronectin etc.) 2)Lamina fibroreticularis contain collagen type III and anchoring fibrils (collagen type VII)

Question 117

Regarding dermal-epidermal junction, which of the following statements is true:
1 There are no anchoring filaments in lamina lucida
2 Lamina fibroreticularis lies above lamina densa
3 Lamina fibroreticularis comprises of anchoring fibrils and the elastic microfibrils
4 Blood vessels cross the dermal-epidermal junction to reach the epidermis
5 Lamina lucida is an electron-dense layer

Answer 117

Lamina fibroreticularis comprises of anchoring fibrils and the elastic microfibrils
Lamina fibroreticularis comprises of anchoring fibrils and the elastic microfibrils. Lamina fibroreticularis lies below lamina densa. Blood vessels don’t cross the dermal-epidermal junction to reach the epidermis. Basement membrane contain both: 1)Lamina basale which include a.lamina lucida and b.lamina densa( which contain collagene IV & other glycoproteins like laminins,fibronectin etc.) 2)Lamina fibroreticularis contain collagen type III and anchoring fibrils (collagen type VII)

Question 118

A 78 year-old man is diagnosed with cicatricial pemphigoid. Which of the following antigens being implicated in his disease should trigger a work-up for malignancy?
1 BPAg2
2 Laminin 5
3 Laminin 6
4 Beta-4 integrin
5 Type VII collagen

Answer 118

Laminin 5
Involvement of Laminin 5 would raise the suspicion for malignancy when found. ~30-40% of cases may have associated malignancy. Patients with antiepiligrin (laminin 5) CP indicated an increased risk of malignancy that approximates that for adults with dermatomyositis. The risk is particularly high in the first year of disease (E-medicine, www.emedicine.com/derm/topic79.htm). Reports of both lung and gastric carcinomas are seen in the literature with some feeling that gastric malignancy is most common.

Question 119

Sebaceous glands:
1 Respond to chemical stimuli such as hormones
2 Respond to cholinergic neural activity, exclusively
3 Respond to adrenergic neural activity, exclusively
4 Respond to both adrenergic and cholinergic stimuli
5 Respond to the local release of cytokines from inflammatory cells

Answer 119

Respond to chemical stimuli such as hormones
Sebaceous glands are androgen-responsive holocrine glands that enlarge at puberty. Meibomian glands of the eyelids are modified sebaceous glands. Sebaceous glands are found everywhere on the skin except the palms and soles. Fordyce�s condition involves free sebaceous glands on the vermillion border of the lips and on the buccal mucosa. Eccrine glands are thermoregulatory structures that respond to cholinergic stimulation.

Question 120

Itch is most commonly transmitted by:
1 C-polymodal nociceptor class nerves
2 A-delta class nerves
3 A-beta class nerves
4 Parasympathetic postganglionic fibers
5 A-beta and A-delta fibers

Answer 120

C-polymodal nociceptor class nerves
 Itch is transmitted primarily by C-polymodal nociceptor class nerves. These are small diameter unmyelinated nerves that carry pain, thermal, mechanical and pruritic stimuli. A-delta fibers carry pain, thermal, mechanical and in some cases pruritic stimuli. A-beta fibers carry light touch and motion stimuli. Parasympathetic post-ganglionic fibers do not contribute to cutaneous pruritus

Question 121

Keratin filaments in basal cells insert into:
1 Desmosomes
2 Adherens junctions
3 Connexins
4 Lamellar granules
5 Odland bodies

Answer 121

Desmosomes
Keratin filaments insert into desmosomes and hemidesmosomes in the basal cell layer and into desmosomes in the layers above. Connexins do not bind keratin filaments. Odland bodies and lamellar granules are synonyms. These are a “membrane bounded organelle, specialized for the storage and secretion various substances (surfactant phospholipids, glycoproteins and acid phosphates) which are arranged in the form of tightly packed, concentric, membrane sheets or lamellae. Has some similar properties to, but is distinct from, a lysosome.”

Question 122

How soon does epithelialization begin after a skin wound occurs?
1 Minutes
2 Hours
3 2 days
4 4 days
5 6 days

Answer 122

Hours
Re-epithelialization begins hours after an injury occurs. Keratinocytes from residual epithelial structures leapfrog each other. One to two days after injury, cells at the wound margin proliferate and begin to migrate into the wound.

Question 123

Platelets release which of the following factors to promote new tissue growth?
1 Neutrophil chemotactic factor
2 IL-1
3 ADP
4 TGF-alpha
5 FGF

Answer 123

TGF-alpha
Platelets release PDGF, TGF-alpha and TGF-beta which promote new tissue growth. FGF and IL-1 are released from monocytes as growth factors (monocytes also release PDGF, TGF-alpha and TGF-beta). ADP is released from platelets, but is not functioning as a growth factor. Neutrophil chemotactic factor is released from mast cells and is an inflammatory mediator.

Question 124

Anagen effluvium is best described as:
1 An abrubt transition from anagen to catagen in rapidly dividing hair matrix cells
2 A cessation of mitotic activity in rapidly dividing hair matrix cells
3 An abrupt transition of telogen to anagen in resting hair matrix cells
4 A cessation of mitotic activity in resting hair matrix cells
5 A scarring alopecia affecting only anagen stage follicles

Answer 124

A cessation of mitotic activity in rapidly dividing hair matrix cells
Anagen effluvium results from an outside stimulus � most often an antimetabolite, chemotherapeutic drug � inducing an abrupt cessation of hair matrix cell mitotic activity. This process occurs within days to weeks of the stimulus, and is reversible with cessation of the drug therapy.

Question 125

Which of the following is true about melanosomes?
1 Spheroid melanosomes have concentric lamellae
2 Spheroid melanosomes synthesize brown-black eumelanin
3 Elliptical melanosomes have microvesicular structure
4 Elliptical melanosomes synthesize yellow or red pheomelanin.
5 The melanosomes are positioned after the Golgi apparatus in the secretory pathway.

Answer 125

The melanosomes are positioned after the Golgi apparatus in the secretory pathway.
Melanosomes are organelles related to lysosomes and are positioned after the Golgi apparatus in the secretory pathway. Elliptical melanosomes have concentric lamellae and synthesize brown-black eumelanin. Spheroid melanosomes have microvesicular structure and synthesize yellow or red pheomelanin.

Question 126

Glomus cells are primarily found:
1 on hands/feet
2 on the trunk
3 on the lateral thighs
4 on the genital skin
5 on the face

Answer 126

on hands/feet
Glomus cells are derived from Susquet-Hoyer canals which function to shunt blood from the arterioles to venules and are primarily found on hands and feet. There are two types of glomus tumors, solitary and multiple. The solitary types tend to have paroxysmal pain which can be extreme. Multiple glomus tumors can be a autosomally dominant trait with incomplete penetrance and are less likely to be painful. Both have a predominance on the distal extremities, especially sub-ungual. Two tests are helpful in diagnosing glomus tumors: Hildreth sign - disappearance of pain following application of a tourniquet proximally. Love test - eliciting pain by applying pressure to a precise area with the tip of a pencil.

Question 127

Which of the following is true regarding the development of hair follicles?
1 The first primordial hair follicles form at 15 weeks gestation
2 The first hair follicles form on the scalp and eyelashes
3 Follicles develop in a cephalad to caudal direction
4 New follicles develop during the first 3 months postpartum
5 The eyebrows develop late in gestation

Answer 127

Follicles develop in a cephalad to caudal direction
The first primordial hair follicles form at 9 weeks gestation on the eyebrows, upper lip, and chin. The remaining follicles develop at 4-5 months in a cephalad to caudal direction. New follicles cannot develop in adult skin.

Question 128

Regarding the stratum spinosum, which of the following is correct?
1 No keratin 1/10 is present
2 New synthesis of K5/14 occurs in this layer
3 The “spines” seen on pathology are due to desmosomal connections between keratinocytes
4 This layer contains melanocytes
5 This layer contains the cornified cell membrane

Answer 128

The “spines” seen on pathology are due to desmosomal connections between keratinocytes
The “spines” seen on pathology are due to desmosomal connections between keratinocytes, NOT hemidesmosomes. The hemidesmosomes are present in the cells at the base of the basal layer and are part of the connection between the epidermis and basement membrane. Keratin expression continues in the spinous layer. Keratins 1/10 are synthesized, not keratins 5/14. Keratin 5/14, however, is still present. Keratohyaline granules are typically seen in the granular layer.

Question 129

What is the most abundant collagen found on fetal skin?
1 Type I Collagen
2 Type II Collagen
3 Type III Collagen
4 Type IV Collagen
5 Type VII Collagen

Answer 129

Type III Collagen
Type III collagen is found in the fetal skin. It is also present in the gastrointestinal tract, blood vessels, and the basement membrane. A defect in this collagen results in the Ehlers-Danlos, vascular type.

Question 130

Sneddon Wilkinson disease is caused by a defect in what antigen?
1 Desmocollin 1
2 Desmoglein 1
3 Desmogelin 3
4 BPAg1
5 BPAg2

Answer 130

Desmocollin 1
Sneddon- Wilkinson disease, also known as sub-corneal pustular dermatosis is due to a defect in desmocollin 1. Desmoglein 1 defect is seen in pemphigus foliaceous and staph scalded skin syndrome. Desmoglein 3 defect is seen in pemphigus vulgaris and intraepidermal neutrophilic IgA dermatosis. BPAg1 is seen in paraneoplastic pemphigus and bullous pemphigoid. BPAg2 is seen in bullous pemphigoid, cicatricial mucous membrane pemphigoid and linear IgA disease.

Question 131

All of the following pertain to Odland bodies EXCEPT:
1 Contain squalene
2 Are found intracellularly in upper level keratinocytes
3 Discharge their contents into the extracellular space at the junction of the granular and cornified layers
4 Establish a barrier to water loss
5 Mediate stratum corneum adhesion in conjunction with filaggrin.

Answer 131

Contain squalene
Odland bodies mediate stratum corneum adhesion in conjunction with FILAGGRIN. They discharge their contents into the extracellular space at the junction of the granular and horny layers establish a barrier to water loss. They are first found intracellularly in upper level keratinocytes and contain ceramides not squalene.

Question 132

Hair follicle development in the human embryo begins during:
1 1st trimester
2 2nd trimester
3 3rd trimester
4 At the blastocoele stage
5 Within 2 weeks of fertiization

Answer 132

1st trimester
Hair follicles begin in the third month of fetal life as a downgrowth of cells from the epidermis (3rd month=12th week=1st trimester).

Question 133

What is the major component of the anchoring fibril?
1 Type I Collagen
2 Type III Collagen
3 Type IV Collagen
4 Type VII Collagen
5 Laminin 5

Answer 133

Type VII Collagen
Anchoring fibrils are made of Type VII collegen. Anchoring plaques are made of Type IV collagen, and interact with a network of Type I And Type III collagen fibers in the dermis.

Question 134

At what estimated gestational age are all layers of the keratinized epidermis identifiable?
1 8 weeks
2 12 weeks
3 16 weeks
4 20 weeks
5 24 weeks

Answer 134

24 weeks
At 24 weeks, all the layers of the mature epidermis can be identified, and the epidermis is keratinized.

Question 135

Choose the correct answer regarding melanin and skin color:

1 In black and brown skin the melanosomes are smaller in diameter and length
2 Facultative skin color is the amount of cutaneous melanin pigment generated according to cellular genetics
3 In white skin the melanosomes form groups within the secondary lysosomes
4 Eumelanin produces a yellow chromophore
5 The number of melanocytes increases with one exposure to UVA/visible light

Answer 135

In white skin the melanosomes form groups within the secondary lysosomes
Melanocytes of dark skin synthesize melanosomes larger than those produced in light skin. The number of melanocytes in the epidermis is the same, regardless of the person’s race or color: it is the number and size of the melanosomes or pigment granules, continuously synthesized by these melanocytes, that determine differences in skin color. The size of th melanosome is the principle factor in determining how the melanosomes will be distributed within the keratinocytes. The larger the melanosomes of dark skin are individually dispersed within the cytoplasm of keratinocytes: smaller melanosomes of light skin are packaged in membrane-bound complexes within keratinocytes. Eumelanin is in dark oval melanosomes found in black hair

Question 136

Odland bodies:
1 Contain keratins
2 Are found intercellularly in the basal cell layer
3 Are exclusively intracellular
4 Crosslink with keratins 5 and 14
5 Are secretory granules with features of lysosomes

Answer 136

Are secretory granules with features of lysosomes
 Odland bodies (AKA lamellar granules) are lamellated bodies containing ceramide, are found intercellularly in upper level keratinocytes; they discharge contents into the extracellular space at the junction of the granular and horny layers, establish a barrier to water loss, and with filaggrin mediate stratum corneum adhesion. Recent studies suggest that they are a type of secretory granule with features of lysosomes. (They contain lamellar-body-derived enzymes that are important in desquamation.)

Question 137

What is the most important cell for wound healing?
1 Fibroblasts
2 Neutrophils
3 Macrophages
4 Lymphocytes
5 Mast cells

Answer 137

Macrophages
Macrophages are the most important cell for wound healing. They secrete TFGs, cytokinas, IL-1, TNF, and PDGF. Neutropenic or lymphopenic patients do not have impaired wound healing, whereas macrophage-deficient (quantity or function) patients heal poorly. Neutrophils however are the first cell type to flood the wound during phage I of inflammation (within first 6-8 hours); this movement is facilitated by TGF-beta. Fibroblasts migrate into the wound by stage II (granulation) where they produced glycosaminoglycans and fibronectin.

Question 138

Type 1 collagen is the most prevalent collagen in skin, accounting for 80% or more of the total collagen in the adult dermis. The next most predominant collagen in adult human dermis is:
1 Type II collagen
2 Type III collagen
3 Type IV collagen
4 Type VII collagen
5 Type XVII collagen

Answer 138

Type III collagen
Type 1 collagen is the most prevalent collagen in skin, accounting for 80% or more of the total collagen in the adult dermis. Type III collagen is the next most predominant collagen in human dermis, accounting for approximately 10%. Type IV collagen is found in basement membranes. Type VII collagen is found in human dermis as anchoring fibrils. Type XVII collagen, also known as BPAG2, is an important transmembrane protein in the basement membrane zone.

Question 139

Tyrosinase is the enzyme that catalyzes the conversion of tyrosine to DOPA and DOPA to DOPAquinone. The enzyme contains which of the following ions?
1 Zinc
2 Copper
3 Selenium
4 Iron
5 Magnesium

Answer 139

Copper
Tyrosinase is a copper containing enzyme that is responsible for the conversion fo tyrosine to DOPA and DOPA to DOPAquinone.

Question 140

Meibomian glands are:
1 Eccrine glands localized to the vermillion border of the lips
2 Sebaceous glands found on the areola of the breast
3 Sebaceous glands found on the eyelids
4 Apocrine glands found in the anogenital regions
5 Apocrine glands found on the eylelids

Answer 140

Sebaceous glands found on the eyelids
Sebaceous glands enlarge at puberty in response to increased levels of androgens. They are holocrine glands. Meibomian glands are modified sebaceous glands found in the eyelids. Free sebaceous glands not associated with hairs are found in the nipple and areola and are called Montgomery�s tubercles. Fordyce�s condition involves free sebaceous glands on the vermillion border of the lips and on the buccal mucosa. Sebaceous glands are found everywhere on the skin except the palms and soles.

Question 141

Tissue contraction begins:
1 At 3rd day of wound healing
2 During the 2nd week of wound healing
3 After the first month of wound healing
4 After the 3rd month of wound healing
5 After the 9th month of wound healing

Answer 141

During the 2nd week of wound healing
Wound healing tends to be a predictable process that begins initially with the inflammatory stage. During this stage, clot formation occurs. This is the initial step in wound healing. Platelets, neutrophils and macrophages all migrate to the wound and secrete many mediators of wound healing. Epithelialization then begins hours after injury. This is followed by granulation tissue formation (four days after injury) and angiogenesis (first week of repair). Wound contraction ensues during the second week of healing.

Question 142

Krause end bulbs are:
1 Adapting mechanoreceptors found on weight-bearing sites that respond to vibrational stimul
2 Found on the vermillion border of the lips
3 Located in the dermal papillae of digital skin
4 Located in the deep dermis and within the subcutis in weight-bearing sites of the body
5 Found at the orifice of the hair follicle and particularly sensitive to cold

Answer 142

Found on the vermillion border of the lips
3 Located in the dermal papillae of digital skin

Krause end bulbs are mucocutaneous receptors found on the glans penis, clitoris, labia minora, perianal area, and vermillion border of the lips. Papillary nerve endings are free nerve endings found at the orifice of the hair follicle and particularly sensitive to cold. Meissner’s corpuscles are ovoid, elongated mechanoreceptors located in the dermal papillae of digital skin that detect touch and light pressure. Pacinian (Vater-Pacini) corpuscles exist in the deep dermis and within the subcutis in weight-bearing sites and function as adapting mechanoreceptors that respond to vibrational stimuli.

Question 143

Retinoids upregulate transcription of which types of collagen?
1 1 and 3
2 1 and 4
3 1 and 7
4 3 and 7
5 4 and 7

Answer 143

1 and 7
Retinoids upregulate the transcription of collagens one and seven thereby strengthening the dermis.

Question 144

Fibrofolliculomas are associated with:
1 Birt-Hogg-Dube Syndrome
2 Cowdens
3 Cutis Laxa
4 Marfans
5 Brook Spiegler

Answer 144

Birt-Hogg-Dube Syndrome
Fibrofolliculomas are associated with Birt-Hogg-Dube Syndrome and not in the other answer choices.

Question 145

Acid keratins (K10-20) are expressed on which of the following chromosomes?
1 17
2 18
3 19
4 10
5 12

Answer 145

17
Acid keratins are expressed on chromosome 17 and basic keratins on chromosome 12. The other listed options do not have active keratin functions.

Question 146

Elaunin fibers:
1 Run parallel in bands within the superficial papillary dermis
2 Run perpendicular from the dermo-epidermal junction within the superficial papillary dermis
3 Run parallel in bands within the reticular dermis
4 Run perpendicular in bands within the deep dermis
5 Run perpendicular in bands within the reticular dermis

Answer 146

Run parallel in bands within the reticular dermis
Elaunin fibers are elastic fibers that have less elastin and more fibrillin and run parallel in thin bands within the reticular dermis. Oxytalin fibers contain no elastin and run perpendicular from the dermo-epidermal junction within the superficial papillary dermis. Elastic fibers turn over slowly in the skin, and are damaged by ultraviolet radiation.

Question 147

Direct immunofluorescence staining of intercellular spaces and the basement membrane zone, in combination, is seen in:
1 Paraneoplastic pemphigus
2 Anti-epiligrin pemphigoid
3 Pemphigus vegetans
4 Pemphigus foliaceous
5 IgA pemphigus

Answer 147

Paraneoplastic pemphigus
Paraneoplastic pemphigus and drug-induced pemphigus demonstrate direct immunofluorescence staining of the intercellular space and the BMZ, in combination. Anti-epiligrin pemphigoid demonstrates BMZ staining (dermal staining on salt-split skin). Pemphigus vegetans, pemphigus foliaceous, and IgA pemphigus all show intercellular space deposition without staining of the BMZ.

Question 148

Apocrine glands:
1 Are coiled glands
2 Have a two segment ducts that empties onto the skin
3 Are present everywhere on the skin except on the palms and soles
4 Function from birth
5 Secretions are initially odorless

Answer 148

Secretions are initially odorless
Apocrine glands are tubular glands that demonstrate decapitation secretion. Like eccrine glands, the ducts are composed of three segments: intraepidermal duct, intradermal duct and secrectory portion. The duct usually leads to a pilosebaceous follicle above the entrance of the sebaceous duct. They are found in the axillae, anogenital region, external ear canal (ceruminous glands), in the eyelids (Moll�s glands) and in the breast (mammary glands). These glands are functional starting at puberty. The initial secretions are odorless with the odor being derived from C6 � C11 acids. The most abundant being 3-methyl-2-hexenoic acid.

Question 149

Meibomian glands are:
1 Modified sebaceous glands
2 Found everywhere except on the palms and soles
3 Sebaceous lobules that feed into a lactiferous duct
4 Modified ceruminous glands
5 Modified apocrine glands

Answer 149

Modified sebaceous glands
Meibomian glands of the eyelids are modified sebaceous glands. Sebaceous glands are found everywhere on the skin except the palms and soles. Montgomery’s areolar tubercles consist of several sebaceous lobules feeding into a lactiferous duct. Ceruminous glands are apocrine glands of the external ear canal. Apocrine glands in the eyelids are Moll’s glands.

Question 150

Defects in what kind of structural protein lead to pyloric atresia associated with junctional epidermolysis bullosa:
1 Collagen
2 Elastin
3 Loricrin
4 Integrin
5 Plectin

Answer 150

Integrin
Junctional epidermolysis bullosa with pyloric atresia involves a defect in the b4 subunit of the a6b4 integrin. The expression of this protein is limited to the basal layer of the epidermis. This integrin is a transmembrane protein that coordinates a link between the intermediate filaments (keratins) and the extracellular matrix of the basement membrane. The b4 domain mediates an interaction with both plectin and BP180; its absence prevents hemidesmosomal assembly.

Question 152

Which of the following is a member of the armadillo family of linking proteins?
1 E-cadherin
2 Periplakin
3 Envoplakin
4 Desmocollin
5 Plakoglobin

Answer 152

Plakoglobin
Plakoglobin is an example of an armadillo protein, which links the cytoskeleton associated linking proteins (such as plakins in the case of intermediate filaments and alpha-catenin in the case of actin) to the transmembrane adhesion molecules, termed cadherins. E-cadherin and desmocollin are examples of cadherins. Periplakin and envoplakin are examples of plakin linking proteins.

Question 153

What percentage of the dry weight of skin in elastin?
1 2
2 4
3 6
4 8
5 10

Answer 153

Elastin fibers make up 4% of dry weight of the skin, forming a complex meshwork extending from lamina densa of the dermoepidermal junction through the dermis and into the hypodermis. Elastins help return the skin to the normal configuration after being stretched. Elastic fibers are 90% elastin wrapped by fibrillin microfibrils. Fibrillin is mutated in Marfan syndrome. The typical amino acids found in elastic fibers are desmosine and isodesmosine. Elastic fibers turn over slowly in the skin and are damaged by ultraviolet radiation.

Question 154

What does a western blot identify?
1 Protein
2 RNA
3 DNA
4 Genes
5 Cell membranes

Answer 154

Protein
A northern blot identifies RNA and a southern blot identifies DNA.

Question 155

For the treatment of drug induced linear IgA bullous dermatosis, after stopping offensive medication, what other treatments may be used?
1 Interferon alpha
2 Interferon gamma
3 Psoralen plus UVA
4 Interleukin 2
5 Dapsone

Answer 155

Dapsone
Dapsone may be used to treat patients with drug induced linear IgA bullous dermatosis which persist after the offending medication has been discontinued. The other medications listed are rare causes of drug induced linear IgA bullous dermatosis and so should not be used for treatment.

Question 156

Homocystinuria has abnormal crosslinking of collagen because of a mutation in:
1 Cystathione synthase
2 Type I collagen N-peptidase gene
3 Lysyl hydroxylase
4 Tenascin X
5 Lysyl oxidase

Answer 156

Cystathione synthase
Homocystinuria is caused by a mutation in cystathione synthase. The main skin findings are a malar flush, livedo reticularis and leg ulcerations. A characteristic eye finding is the downward displacement of the lens. The other options are involved in abnormalities associated with Ehlers-Danlos syndrome. Lysyl hydroxylase is deficient in Kyphoscoliosis type of EDS. Tenascin X is involves in ~3% of Classical type EDS cases. Dermatosparaxis type EDS has recessive mutations in the type I collagen N-peptidase gene.

Question 157

LEMD3 is mutated in which of the following syndromes?
1 Buschke Ollendorf
2 Albright Hereditary Osteodystrophy
3 Goltz
4 McCune-Albright
5 Menkes

Answer 157

Buschke Ollendorf
LEMD3 or MAN1 is mutated in Buschke-Ollendorf syndrome. Common skin findings include dermatofibrofibrosis lenticularis disseminata. The radiographic finding commonly seen is osteopoikilosis. The gene defect was recently described as MAN1/LEMD3, a gene encoding for a nuclear membrane protein. Albright Hereditary Osteodystrophy is caused by inactivation of GNAS1, Goltz is an x-linked dominant condition with unknown pathogenesis, McCune-Albright syndrome is caused by an activation of GNAS1. Menke’s Syndrome is caused by a defect in ATP7A/MKN on Xq13.

Question 158

Homocystinuria is an autosomal recessive condition with findings including a marfanoid habitus, downward dislocation of the lens, cardiovascular disease and mental retardation. It is caused by a mutation in cystathionine beta-synthetase. What does this mutation in cystathionine beta-synthetase cause other than an accumulation of homocystine?
1 Abnormal crosslinking of collagen
2 Abnormal development of elastin fibers
3 Melanocyte death
4 Pigmentation of cartilage
5 Black urine

Answer 158

Abnormal crosslinking of collagen
Excess homocystine leads to abnormal crosslinking of collagen, with only ~1/3 of crosslinking activity compared to normal controls (OMIM 236200). The other listed findings are not features of homocystinuria, though hypopigmentation can be a featur

Question 159

Apocrine glands are found in all of the following areas of the body except:
1 Axillae
2 Breasts
3 Eyelid
4 Palms
5 Perineum

Answer 159

Palms
Apocrine glands operate by decapitation secretion and are activated by epinephrine and norepinephrine. They are located in a few distinct areas of the body, which include axillae, anogenital region, Moll�s glands of the eyelids, mammary glands of the breast and the ceruminous glands of the external auditory canal.

Question 160

During embryogenesis, periderm cells of the fetus contain which of the following substances?
1 Ceramide
2 Glycogen
3 Free fatty acids
4 Porphyrins
5 Sebum

Answer 160

Glycogen
In week 7 of embryogenesis the surface ectoderm produces two layers. The external layer is the periderm which contains glycogen and gives rise to the stratum corneum by week 21. The other layer is the stratum germinativum.

Question 161

Desmoglein 1 is the antigen in which of the following autoimmune diseases of the skin:
1 Pemphigus foliaceus
2 Bullous impetigo
3 Dermatitis herpetiformis
4 Bullous pemphigoid
5 Pemphigoid gestationis

Answer 161

Pemphigus foliaceus
The antigen implicated in pemphigus foliaceus is Desmoglein 1. Desmoglein 1 is targeted in bullous impetigo, but this is an infectious condition, not an autoimmune disease. The antigen in dermatitis herpetiformis is transglutaminase 3. The antigens for both bullous pemphigoid and pemphigoid gestationis are BPAG1 and BPAG2.

Question 162

Anagen effluvium is
1 Rarely seen following administration of cancer chemotherapeutic agents
2 Stimulus induces the abrupt cessation of miotic activity in the rapidly dividing hair matrix cells
3 Occurs within 24 to 48 hours of exposure
4 Entirely inreversible
5 Patients being treated with nitrosurea agents are usually spared

Answer 162

Stimulus induces the abrupt cessation of miotic activity in the rapidly dividing hair matrix cells
It is frequently seen following administration of cancer chemotherapeutic agents. Stimulus induces the abrupt cessation of mitotic activity in the rapidly dividing hair matrix cells. Occurs within days to weeks following exposure to the inciting agent and is entirely reversible. Frequent causes include antimetabolites, alkylating agents, mitotic inhibitors, thallium, boron. Frequent causes include doxorubicin, nitrosureas and cyclophosphamide.

Question 163

Keratinocytes have been shown to secrete all of the following cytokines except:
1 IL-1
2 IL-6
3 IL-8
4 TNF-alpha
5 IL-2

Answer 163

IL-2
Keratinocytes have been shown to secrete all of the above cytokines, except IL-2, IL-4, and IFN-gamma.

Question 164

Fragmentation and/or loss of elastic fibers in not seen in:
1 Cutis laxa
2 Marfan’s syndrome
3 Anetoderma
4 Psuedoxanthoma elasticum
5 Buschke-Ollendorf syndrome

Answer 164

Buschke-Ollendorf syndrome
Cutis laxa results from decreased desmosine and lysyl oxidase and demonstrates fragmentation and loss of elastic fibers. Marfan’s sydnrome results from decreased fibrillin I and demonstrates fragmentation of elastic fibers. Pseudoxanthoma elasticum demonstrates increased glycosaminoglycans on elastic fibers and the accumulation of fragmented and calcified elastic fibers. Anetoderma has decreased desmosine and demonstrates loss and fragmentation of elastic fibers. Buschke-Ollendorf syndrome exhibits increased desmosine and an increased amount of thickened elastic fibers.

Question 165

Sebaceous glands use what type of secretion?
1 Exocrine
2 Endocrine
3 Apocrine
4 Holocrine
5 Merocrine

Answer 165

Holocrine
Sebaceous glands are associated with holocrine type secretion (release by rupture of the plasma membrane). Apocrine is used to describe decapitation secretion for the cell (as seen in apocrine glands). Merocrine secretions are characterized by exocytosis (salivary glands as well as some eccrine and apocrine glands). Exocrine and Endocrine describe glands that secrete directly into the extracellular environment and directly into the blood stream respectively.

Question 166

Apocrine glands:
1 Demonstrate holocrine secretion
2 Demonstrate decapitation secretion
3 Are fully functional at birth
4 Are diffusely distributed on the body
5 Are thermoregulatory

Answer 166

Demonstrate decapitation secretion
Apocrine glands show decapitation secretion. Like eccrine glands, apocrine glands are composed of three segments, the intraepidermal duct, the intradermal duct, and the secretory portion. The duct of the apocrine gland usually leads to a pilosebaceous follicle above the entrance of the sebaceous duct. Apocrine glands are found in the axillae, anogenital region, external ear canal (ceruminous glands), in the eyelids (Moll�s glands), and in the breast (mammary glands). Apocrine glans are functional only at puberty. Their initial secretion is odorless. Hidradenitis suppuritiva is a disease involving apocrine glands.

Question 167

Which of the following markers are specific and reliable for Merkel cells?
1 CD20
2 HMB-45
3 CD34
4 CD3
5 CK20

Answer 167

CK20
Cytokeratin (CK) 20 is a reliable marker for Merkel cells. CD20 is a marker for B-cells and CD3 is a T-cell marker. HMB-45 is used in staining for immature melanosomes and is reactive in melanoma. CD34 is used to stain dermatofibrosarcoma protuberans.

Question 168

The antibody target in ocular cicatricial pemphigoid is also mutated in:
1 Junctional epidermolysis bullosa, Herlitz type
2 Recessive dystrophic epidermolysis bullosa
3 Junctional epidermolysis bullosa with myotonic dystrophy
4 Dominant dystrophic epidermolysis bullosa
5 Junctional epidermolysis bullosa with pyloric atresia

Answer 168

Junctional epidermolysis bullosa with pyloric atresia
JEB with pyloric atresia and ocular cicatricial pemphigoid both have mutations in Beta4integrin. Herlitz type JEB is due to laminin 5. Recessive and dominant dystrophic EB is due to COL17A1 (type VII collagen). JEB with myotonic dystrophy is due to plectin.

Question 169

The function of glycosaminoglycans/proteoglycans in the dermis is:
1 Regulate water-binding capacity
2 Interact with dermal dendrocytes
3 Facilitate COLVII binding to the anchoring plaques
4 Facilitate mast cell degranulation
5 Regulate lymphocyte trafficking

Answer 169

Regulate water-binding capacity
The function of glycosaminoglycans/proteoglycans in the dermis is to regulate water-binding capacity. The other listed options are not functions of glycosaminoglycans / proteoglycans.

Question 170

Which component of hair is positive for citrulline?
1 Outer root sheath
2 Inner root sheath
3 Cortex
4 Glassy vitreous layer
5 Medulla

Answer 170

Inner root sheath
The inner root sheath stains red because it contains citrulline. The cortex and medulla along with the cuticle make up the hair shaft. The outer root sheath is the most peripheral cellular structure. The glassy vitreous layer is the basement zone equivalent of hair and is the outermost layer.

Question 171

S100 staining would be negative in?
1 langerhans cells
2 eccrine cells
3 schwann cells
4 adipocytes
5 keratinocytes

Answer 171

keratinocytes
S100 is sensitive for melanocytes and melanoma, but not specific as it also stains langerhans cells, eccrine cells, schwann cell, adipocytes, and chondrocytes. It is negative in keratinocytes and can help discriminate melanoma from pagetoid bowens or spindle cell squamous cell carcinoma.

Question 172

The desmosomal connections of the epidermis are dependent on which of the following ions?
1 Iron
2 Zinc
3 Selenium
4 Calcium
5 Sodium

Answer 172

Calcium
The desmosomal connections in the epidermis are calcium dependent. The other options are not required for these connections.

Question 173

Sebaceous glands secrete sebum through which of the following secretory mechanisms?
1 Holocrine
2 Merocrine
3 Apocrine
4 Holocrine and Merocrine
5 Holocrine and Apocrine

Answer 173

Holocrine
Sebaceous glands exhibit holocrine secretion, whereby the sebocytes disintegrate in transit to the gland center, releasing their sebum contents. Merocrine secretion refers to the formation of intracellular secretory vesicles that translocate to the apical cell surface for secretion. Apocrine secretion refers to the process whereby secretory contents are packaged using the apical cell membrane, and ‘pinched off’ to achieve secretion.

Question 174

The triple helix of the collagen molecule is largely maintained due to its amino acid composition. The polypeptide chains of collagen are repeating triplets of Glycine-X-Y. The X and Y positions can be occupied by multiple amino acids, but are most often:
1 Alanine and asparagine
2 Tyrosine and threonine
3 Histidine and ornithine
4 Leucine and isoleucine
5 Proline and hydroxyproline

Answer 174

Proline and hydroxyproline
Collagen fibers provide tensile strength to the skin and allow it to serve as a protective organ against the external environment. Collagen makes up 80% of the dry weight of the dermis. The structure of collagen is comprised of three alpha chains arranged into a triple helix. The repeating amino acid triplets of the triple helix of collagen are most often Glycine-Proline-Hydroxyproline.

Question 175

Surgery, Parturition, Fever, Kwashiokor and Hypervitaminosis A are all causes of:
1 Telogen effluvium
2 Anagen effluvium
3 Alopecia areata
4 Androgenetic alopecia
5 Both telogen and anagen effluvium

Answer 175

Telogen effluvium
All of the listed stressors can induce telogen effluvium. Other causes include traction and some drug exposures. Usually will only involve up to 50% of scalp hairs and will resolve within 2-3 months.

Question 176

Which cell type is required for wound healing?
1 Macrophage
2 Lymphocyte
3 Mast cell
4 Dermal dendrocyte
5 Neutrophil

Answer 176

Macrophage
The macrophage is required for wound healing. Without macrophages, there is no healing. Macrophages debride tissue through phagocytosis and digestion of organisms, tissue debris and effete PMN’s. They secrete collagenase and secrete growth factors that facilitate transition from inflammation to repair.

Question 177

Keratinocytes are derived from which of the following:
1 Endoderm
2 Mesoderm
3 Ectoderm
4 Neural Crest
5 Bone marrow precursors

Answer 177

Ectoderm
As implied by the root ‘ecto’, a prefix meaning “outer”, the keratinocytes of the epidermis are derived from the ectoderm. The other layers do contribute cell populations that are present in the skin.

Question 178

Keratohyalin granules contain:
1 Desmoplakin
2 Envoplakin and Keratin 6
3 Profilaggrin and loricrin
4 Numerous Golgi apparati
5 Involucrin

Answer 178

Profilaggrin and loricrin
Keratohyalin granules are found in the stratum granulosum (the granular layer), and contain the proteins profilaggrin and loricrin. Profilaggrin is converted to filaggrin during the transformation of the granular layer to the cornified layer. This is a calcium-dependent process. Loricrin comprises 75% of the cornified envelope�s mass.

Question 179

Which mechanoreceptor found in hair bearing areas sense deep touch and vibration?
1 Merkel cell
2 Meissner corpuscle
3 Vater-Pacini corpuscle
4 Krase end-bulb
5 Free nerve ending

Answer 179

Vater-Pacini corpuscle
Vater-Pacini corpuscles sense deep touch and vibration. Merkel cells are slow adapting type I mechanoreceptors found among basal keratinocytes. Meissner corpuscles are found in the dermal papilla, especially in the palms and soles. Krase end-bulbs are mucocutaneous end-organs found on the glans penis, prepuce, clitoris, labia minora, and vermillion border of the lip.

Question 180

BP230 is a member of of which of the following families?
1 Plakin
2 Integrin
3 Laminin
4 Collagen
5 Elastin

Answer 180

Plakin
BP230 is a member of the plakin family and is homologous to desmoplakin and is intracellular. It attaches intermediate filaments to hemidesmosomal plaque. The remaining options are not part of the plakin family.

Question 181

Mutations in which of the following genes will produce red hair?
1 MC1-R
2 Agouti
3 Hairless
4 c-kit
5 Tyrosinase

Answer 181

MC1-R
MC1-R is the receptor that binds alpha-MSH, and ACTH>alpha-MSH. Defects in this receptor will produce a phenotype including red hair. Agouti is not involved in this process. Agouti describes the banding of hairs seen in some mammals such as dogs, foxes, and mice, which is due to alternating production of eumelanin and pheomelanin occurs. This has not been described in humans (Bolognia, p942). The hairless gene is associated with alopecia totalis. C-kit mutations are associated with piebaldism and urticaria pigmentosa. Tyrosinase defects are associated with Type I Oculocutaneous albinism.

Question 182

Which hair condition is associated with abnormal regulation of the peroxisome proliferator-activated receptor-γ (PPARγ):
1 Alopecia areata
2 lichen planopilaris
3 telogen effluvium
4 seborrheic dermatitis
5 androgenic alopecia

Answer 182

lichen planopilaris
Lichen planopilaris is a chronic, scarring condition that results in permanent loss of hair and destruction of the hair follicles. Defect in lipid metabolism and peroxisome biogenesis may contribute to LPP pathogenesis. Medications that act as PPAR agonists, such as pioglitazone, may have a role in controlling the progression of this disease. (Karnik P, et al. (2009) Hair follicle stem cell-specific PPAR deletion causes scarring alopecia. J Invest Dermatol 129:1243â57)

Question 183

Which of the following dermal cells always express CD11c and CD6?
1 Mononuclear phagocytic cells
2 Fibroblasts
3 Mast cells
4 Erythrocytes
5 Glomus cells

Answer 183

Mononuclear phagocytic cells
The mononuclear phagocytic cell includes monocytes, macrophages and dermal dendrocytes. All phagocytic skin macrophages express CD11c and CD6. Fibroblasts do not produce a CD marker. Mast cells are derived from bone marrow-residing CD34+ stem cells. They do not produce CD11c or CD6.

Question 184

Mutations in which of the following proteins results in epidermolysis bullosa simplex associated with muscular dystrophy:
1 Uncein
2 Plectin
3 a6b4 integrin
4 Laminin 5
5 Collagen type IV

Answer 184

Plectin
Anchoring filaments exist within the lamina lucida. They are primarily comprised of laminin 5 and BP180. Laminin 5 is a cross-shaped assembly of 3 classes of polypeptides, a, b, g. The anchoring filaments function as a structural network to which other proteins attach, and they function as signaling molecules that transmit morphogenetic information to transmembrane proteins of the basal cell layer (such as the integrins). Laminin 5 is also called epiligrin and binds to the a6b4 integrin at the hemidesmosome.

Question 185

The classical types of Ehlers-Danlos Syndromes (Type 1 and 2) lead to varying degrees of hyperextensible skin, easy bruising, wide, atrophic scars, and hypermobile joints. The underlying defect in this disorder is a mutation in:
1 Elastin
2 Fibrillin 1
3 ABCC6
4 Collagen V
5 Cystathionine beta-synthase

Answer 185

Collagen V
Classical types of Ehrlers-Danlos are manifested by varying degrees of hyperextensible skin, easy bruising, wide, atrophic scars, and hypermobile joints. The genetic defect is in Collagen V. Elastin is mutated in Cutis Laxa. ABCC6 is defective in Pseudoxanthoma elasticum. Cystathionine beta-synthase is mutated in homocystinuria.

Question 186

Which keratins are upregulated in hyperproliferative disease such as psoriasis?
1 Keratins 1 and 10
2 Keratins 2e and 10
3 Keratins 5 and 14
4 Keratins 6 and 16
5 Keratins 8 and 18

Answer 186

Keratins 6 and 16
Keratins 6 and 16 are upregulated in hyperproliferative keratinocytes, outer root sheath, and oral epithelium. A defect in these keratins may result in pachyonychia congenita.

Question 187

Numerous neuromediators are involved in cutaneous neurobiology and many play a role in the development of inflammation in the skin. One such mediator can be induced by application of capsaicin to the skin. Which of the following is the correct neuromediator?
1 Noradernaline
2 Substance P
3 Neurokinin A
4 Acetylcholine
5 Pro-opiomelanocortin

Answer 187

Substance P
Substance P is a neuromediator that binds the tachykinin receptor. It is released upon stimulation of sensory nerve fibers. It has numerous cutaneous functions, including development of skin edema, erythema, and pruritus, upregulation of adhesion molecule expression, release of proinflammatory mediators, etc. Capsaicin causes release of substance P. This has been utilized pharmacologically in conditions such as zoster, in which consistent application of capsaicin leads to depletion of substance P, which in turn can help to reduce/eliminate post-herpetic neuralgia. The other answer choices are also neuromediators that are involved in cutaneous inflammation, but their release is not induced by capsaicin.

Question 188

The microflora of pilosebaceous unit consist of which of the following:
1 Pityrosporum ovale
2 Staphylococcus aureus
3 Escherichia coli
4 Pseudomonas aeruginosa
5 Corynebacterium diphtheriae

Answer 188

Pityrosporum ovale
All the above bacteria and fungi are found within sebaceous glands; the Malasssezia spp. and P. ovale are found within the acroinfundibulum, S. epidermidis is found within the midinfundibulum, and Propionibacterium spp. deep within the follicle.

Question 189

What is the significance of the critical line of Auber?
1 It is the location of the insertion of the erector pili muscle
2 the bulk of the mitotic activity in the hair occurs above this line
3 the inner root sheath is formed above this line
4 It is the widest diameter of the hair bulb
5 It is where keratinization first occurs in the hair

Answer 189

It is the widest diameter of the hair bulb
The critical line of Auber is at the widest diameter fo the hair bulb. Below this line, the bulk of mitotic activity that gives rise to the hair and the inner root sheath occurs. The erector pili muscle inserts in the isthmus region of the follicle. Keratinization first occurs above this line.

Question 190

Which hormone is homologous to alpha-MSH (melanocyte stimulating hormone)?
1 Insulin
2 Human growth factor
3 Prolactin
4 Thyroid stimulating hormone
5 Adrenocorticotropic hormone

Answer 190

Adrenocorticotropic hormone
Both alpha-MSH and ACTH are cleavage products of proopiomelanocortin (POMC).

Question 191

Where are glomus cells derived from?
1 Mesenchyme
2 Bone marrow
3 Susquet-Hoyer canal
4 Skeletal muscle
5 Dermis

Answer 191

Susquet-Hoyer canal
Glomus cells are vascular smooth muscle cells derived from the arterial portion of the glomus body, or the Sucquet-Hoyer canal, which is an arteriovenous shunt in the dermis that contributes to temperature regulation. Glomus are found primarily on the palms and soles and function to allow the rapid shunting of blood from the arteioles to venules. Disease processes involving glomus cells include glomus tumor and glomangioma.

Question 192

Which of the following diseases has decreased or absent lamellar granules?
1 Flegel’s
2 Psoriasis
3 Lamellar ichthyosis
4 Epidermolytic hyperkeratosis
5 Pemphigus vulgaris

Answer 192

Flegel’s
Flegel’s disease has decreased or absent lamellar granules. AKA hyperkeratosis lenticularis perstans, this is a rare, possibly AD disorder with multiple disc-like keratotic papules predominenty on the distal extremities and feet of older individuals (Bolognia, p 1714).

Question 193

The strength of a scar:
1 Is 5% at 1 week
2 Is 20% at 3 weeks
3 Is 70% at 1 year
4 All of these options are correct
5 None of these options are correct

Answer 193

All of these options are correct
A scar has 5% strength at 1 week, 20% at 3 weeks and 70% at 1 year. It will never recover strength to the level of pre-injury.

Question 194

Merkel cells are mechanoreceptors found in areas of high-tactile sensitivity. This immunohistochemical marker is restricted to Merkel cells in the skin and is thus a reliable marker for these cells:
1 Keratin 7
2 Keratin 20
3 S-100
4 Factor XIIIa
5 LYVE-1

Answer 194

Keratin 20
Keratin 20 is reliable immunohistochemical markers for Merkel cells as it is restricted to these cells in the skin. Keratin 7 can be used as a marker for Paget’s Disease. S-100 is frequently used to stain neural cells and melanocytes. Factor XIIIa can be used to differentiate a dermatofibroma from dermatofibroma sarcoma pertuberans (positive in DF; negative in DFSP). LYVE-1 is a marker for lymphatics.

Question 195

During hair follicle development, the WNT signaling pathway is one of the earliest molecular pathways involved in hair follicle initiation. What is the downstream mediator of WNT signaling?
1 Smoothened
2 Beta-catenin
3 Keratin 16
4 p53
5 HLA-B27

Answer 195

Beta-catenin
Beta-catenin is the downstream mediator of WNT signaling. Through a series of signals, WNT proteins inhibit the degradation of beta-catenin in the cytoplasm. After being translocated to the nucleus, beta-catenin then forms a complex with LEF/TCF transcription factors, which ultimately results in expression of downstream genes. Activation of this pathway is necessary for epithelium to have the potential to develop a hair follicle.

Question 196

Sebaceous glands form a lipid-rich substance called sebum and are usually associated with a hair follicle. They secrete sebum by what mechanism?
1 Vacuolar exocytosis
2 Passive diffusion
3 Decapitation secretion
4 Autocrine secretion
5 Holocrine secretion

Answer 196

Holocrine secretion
Sebaceous glands form a lipid-rich substance called sebum and are usually associated with a hair follicle. They secrete sebum by means of holocrine secretion which means that they exude lipids by disintegration of entire sebocytes. Sebum contains numerous lipids including cholesterol, cholesterol esters, triglycerides, squalene, and wax esters. Sebaceous glands are regulated by androgens and the activity can be regulated by retinoids.

Question 197

A salt split skin DIF is performed on a biopsy taken adjacent to the skin lesions shown. Where would you expect staining to be seen?
1 Epidermal side
2 Dermal side
3 Epidermal and Dermal sides equally
4 In the lamina densa
5 In the anchoring plaques

Answer 197

Epidermal side
The image shown is bullous pemphigoid. On salt split skin DIF exams, deposits are seen on the epidermal side of the split. If dermal deposits are seen, epidermolysis bullosa acquisita or anti-epiligrin pemphigoid are potential diagnoses.

Question 198

Sebaceous carcinoma stains positive for:
1 EMA
2 CEA
3 S100
4 cKIT
5 CD1a

Answer 198

EMA
Sebaceous carcinomas stain positive for EMA. The other answer choices are incorrect as they do not stain positive in sebaceous carcinoma.