Basic Science and Structure of the Skin Flashcards
1- This wound is in the first phase of healing. What is the best term to describe this initial phase?
A. Proliferative
B. Regenerative
C. Inflammatory
D. Vascularization
E. Remodeling
Correct choice: C. Inflammatory
Explanation: Wound healing can be described with 3 phases: inflammatory, proliferative, and remodeling. The other options represent different phases or aspects that are critical to wound healing, but inflammation is the initial stage.
2- Eccrine glands are found on the:
A. Labia majora
B. Labia minora
C. Glans
D. Prepuce
E. Vermilion
Correct choice: A. Labia majora
Explanation: Eccrine glands are present all over the body except on the vermilion of lips, glans, labia minora, nail beds, and inner prepuce.
3- This patient has metastatic colon cancer and biopsy was done to rule out cutaneous metastases. Pathology showed abundant granulation tissue. What is the best description of the cellular composition of this healing tissue?
A. macrophages, fibroblasts, endothelial cells
B. neutrophils, macrophages, eosinophils
C. keratinocytes, fibroblasts
D. eosinophils, macrophages
E. mast cells, endothelial cells
Correct choice: A. macrophages, fibroblasts, endothelial cells
Explanation: Granulation tissue is composed most correctly of macrophages, fibroblasts, endothelial cells. Eosinophils, keratinocytes, and mast cells are less prominent in the makeup of granulation tissue.
4- Which part of the matrix gives rise to the dorsal nail plate?
A. Distal matrix
B. Proximal matrix
C. Ventral matrix
D. Dorsal matrix
E. Lateral matrix
Correct choice: B. Proximal matrix
Explanation: The proximal matrix gives rise to the dorsal nail plate. The distal matrix gives rise to the ventral nail plate.
5- What is the major determinant of sodium chloride concentration of eccrine sweat that is secreted onto the surface of the skin?
A. Temperature
B. Acetylcholine concentration in nerve endings
C. Sweat rate
D. Dietary salt intake
E. Ph
Correct choice: C. Sweat rate
Explanation: The composition of human eccrine sweat includes inorganic ions (sodium chloride, bicarbonate, potassium), urea, lactate, ammonia, amino acids, proteases, and other proteins. The sweat rate is the major determinant of sodium chloride concentration of eccrine sweat that is secreted onto the surface of the skin. Eccrine sweat is secreted from eccrine glands via merocrine secretion. The substance secreted is initially isotonic but becomes hypotonic as NaCl reabsorption occurs in the eccrine duct. The sweat rate determines how much reabsorption occurs, and thus determines the final concentration of eccrine sweat that reaches the skin surface. Eccrine glands play an important role in the regulation of body temperature. They are distributed over the entire body skin, but are highest in density on the palms and soles. Eccrine glands secrete a salty solution, which reaches the skin pores via an eccrine duct. Eccrine sweat is a sterile electrolyte solution primarily containing sodium chloride, potassium and bicarbonate, with smaller quantities of various other components such as glucose and antimicrobial peptides. Sweat rate differs depending on site on the body, the degree of thermal or physical stress, and between individuals. Under maximal stimulation, the body can produce 3 liters of eccrine sweat per hour.
6- A mother presents to your pediatric dermatology clinic for further evaluation of her daughter, who has red gums, episodic hair loss, and rough perifollicular papules on the arms and thighs. She reports a family history of similar findings. After a thorough assessment of this patient, you conclude the patient has:
A. Pili annulati
B. Pili trianguli et canaliculi
C. Hereditary mucoepithelial dysplasia
D. Wooly hair
E. None of the above
Correct choice: C. Hereditary mucoepithelial dysplasia
Explanation: Defects of the hair shaft include hereditary mucoepithelial dysplasia which is characterized by red gums, episodic hair loss, and keratosis pilaris. Pili annulati is known as banded hair. Uncombable hair syndrome results in triangle-shaped hair. Naxos syndrome is characterized by wooly hair, hyperkeratosis of the palms & soles, and cardiac arrhythmias.
7- Occlusive moisturizers prevent evaporative water loss to the environment by placing an oily substance on the skin surface through which water cannot penetrate. This replenishes the stratum corneum by water movement from the viable epidermal and dermal layers. There are many different classes of chemicals that can function as occlusive moisturizers. What is the most effective occlusive moisturizer?
A. Glycerin
B. Petrolatum
C. Vegetable oil
D. Dimethicone
E. Ceramide
Correct choice: B. Petrolatum
Explanation: The most effective occlusive moisturizer is petrolatum, since it reduce transepidermal water loss by 99%. Petrolatum allows barrier repair while permeating throughout the interstices of the stratum corneum.
a- Glycerin: Humectants are substances that attract moisture; they include: glycerin, honey, sodium lactate, urea, propylene glycol, sorbitol, pyrrolidone carboxylic acid, gelatin, hyaluronic acid, and some vitamins and proteins. Some astringents designed for dry skin contain a humectant liquid moisturizer, such as propylene glycol or glycerin, and skin soothing agents, such as allantoin, guaiazulene or quaternium-19. Glycerin is not the most effective occlusive moisturizer.
c- Vegetable oil: There are many different classes of chemicals that can function as occlusive moisturizers, such as vegetable oils (castor oil, corn oil, grape seed oil, soybean oil). Vegetable oil and wax is a moisturizer type that composes castor oil, corn oil, ozokerite, beeswax, paraffin and carnauba wax. There are many different classes of chemicals that can function as occlusive moisturizers such as vegetable oil. Vegetable oil is not the most effective occlusive moisturizer.
d - Dimethicone: There are many different classes of chemicals that can function as occlusive moisturizers such as silicones (dimethicone, cyclomethicone). Dimethicone and ceramides are moisturizer types that compose water, petrolatum, dimethicone, and ceramics. Dimethicone is not the most effective occlusive moisturizer.
e - Ceramide: There are many different classes of chemicals that can function as occlusive moisturizers such as sterols (cholesterol and ceramides). Dimethicone and ceramides are moisturizer types that compose water, petrolatum,dimethicone, and ceramics. Ceramides are not the most effective occlusive moisturizers.
8- What structure is indicated by the arrow in this Mohs frozen section?
A. Erector pili muscle
B. Nerve
C. Hair shaft
D. Sebaceous gland
E. Vein
correct choice: A. Erector pili muscle
Explanation: A collection of elongated smooth muscle cells at a 45 degree angle in associated with a hair follicle is consistent erector pili muscle. Nerves are a bundle of spindled cells and are typically not seen in the upper dermis, and are not at a 45 degree angle, nor in connection with a hair follicle. Veins consistent of endothelial cells that would be lining a lumen; the lumen may appear collapsed. A hair shaft should be surrounded by various layers and sheaths, and is not made up of spindle cells. Sebaceous glands a a round collection of lobulated cells, not spindled cells, and are seen in association with a hair follicle.
9- The desmosomal connections of the epidermis are dependent on which of the following ions?
A. Iron
B. Zinc
C. Selenium
D. Calcium
E. Sodium
correct choice: D. Calcium
Explanation: The desmosomal connections in the epidermis are calcium dependent. The other options are not required for these connections. Desmogleins and desmocollins are cadherins (calcium-dependent adherence molecules)
10- A patient presents with a chronic pruritic papular eruption in both axillae. You suspect she may have Fox-Fordyce disease, due to an occlusion of apocrine ducts. Which of the following is also true of apocrine glands?
A. Parasympathetic innervation
B. Not present at birth
C. Stains with S100 and keratin
D. Denervation abolishes response to emotive stimuli
E. Distributed over the entire cutaneous surface
Correct choice: C. Stains with S100 and keratin
Explanation: Apocrine glands are innervated by sympathetic fibers. They are present at birth but do not enlarge until hormonal stimulation from puberty. Apocrine glands stain positive for S100, keratin, CEA, and lysozyme. Secretion is in response to emotive stimuli through action of epinephrine/norepinephrine. Denervation does not abolish this response although apocrine sweating requires intact nerve supply. Apocrine sweat glands are confined to certain anatomic locations (axillae, anogenital region, periumbilical region, areolae, nipples, vermilion border of the lip).
11- As the shown wound heals and matures, which cell type is most important for wound contraction?
A. Macrophages
B. Neutrophils
C. Fibroblasts
D. Myofibroblasts E.Endothelialcells
correct choice: D. Myofibroblasts
Explanation: Myofibroblasts are modified fibroblast with smooth muscle like features. Myofibroblasts play the important role in the contraction of the wound that occurs during the proliferation phase. The contraction is considered one of the important events in wound healing because it results in the closure of the wound. The correct balance between too little contraction, which leads to non-healing wounds, and too much contraction, which leads to contractures, is important for optimal healing. The other cell types do not play a large role in wound contraction.
12- Which type of collagen is the first to be deposited in a healing wound?
A. Type I
B. Type II
C. Type III
D. Type IV
E. Type V
Correct choice: C. Type III
Explanation: During the proliferative phase of wound healing, granulation tissue is formed, which relies on presence of fibronectin. Fibronectin is then replaced by collagen type III, and ultimately by
collagen type I. Wound contraction then ensues during the second week of wound healing, a process that is mediated by myofibroblasts. The remaining answer choices are incorrect.
13- Which of the options below, per high concentrations noted in recent studies, is the most important factor in the pathogenesis of SJS/TEN?
A. Granzyme B
B. TNF-β
C. IL-8
D. Caspase
E. IL-3
Correct choice: A. Granzyme B
Explanation: While the pathogenesis of SJS and TEN is not exactly understood, Granzyme B has been shown to be a key factor due to high concentrations present in affected skin. TNF-alpha, perforin and FasL have also been shown to be key to the development of the adverse drug dermatosis. The other cytokines listed are not as critical in the development of SJS/TEN.
14- This patient presents with chronic swelling of the lower extremities, and circumferential lesions on both lower legs as shown in this image. What is the most likely diagnosis?
A. Chronic venous stasis
B. Elephantiasis nostras verrucosa
C. Deep fungal infection
D. Peripheral arterial disease
E. Pigmented purpura dermatosis (Schamberg’s disease)
Correct choice: B. Elephantiasis nostras verrucosa
Explanation: Elephantiasis nostras verrucosa is complication from chronic ymphedema. It commonly affects distal feet and lower extremities leading to verrucous changes with papillomatosis and hyperkeratosis. The other options would not lead to circumferential verrucous lesions on both lower extremities.
15- A child with a stahylococcal infection has an exfoliative dermatitis. The pathogenesis of this eruption is similar to what disease?
A. Paraneoplastic pemphigus
B. Epidermolysis bulls simplex
C. Scarlet fever
D. Pemphigus foliaceous
E. Toxic epidermal necrolysis
Correct choice: D. Pemphigus foliaceous
Explanation: Staphylococcal scalded skin syndrome (SSSS) is descibed, a staphylococcal infection that has exfoliative properties, and the pathogenesis involves serine proteases binding desmoglein 1. This explains the clinical similarities between pemphigus foliaceous and SSSS. The other answer choices are not similar in pathogenesis to that of staphylococcal scalded skin syndrome.
16- Botulinum toxin acts by reducing the amount of acetylcholine release from nerve endings and can be targeted for use on sweat glands for hyperhidrosis. Which of the following sites has the greatest density of these sweat glands?
A. Nipple
B. Clitoris
C. Labia minora
D. External auditory canal
E. Vermilion lips
correct choice: A. Nipple
Explanation: A is correct. The question refers to eccrine glands, which are innervated by postganglionic sympathetic fibers and use acetylcholine as their neurotransmitter. They are targeted by botulinum toxin for hyperhidrosis (in contrast to apocrine glands; innervation of these glands is less clear). All of the following sites except for the nipple (A) lack eccrine glands.
17- An 80-year-old man with Parkinson’s disease developed a new pruritic eruption with these cutaneous findings. What is the antigenic target of the autoantibodies generated in this condition?
A. NC16A domain of BPAg1
B. NC16A domain of BPAg2
C. C-terminal of BPAg1
D. C-terminal of BPAg2
E. alpha-6-beta-4 integrin
Correct choice: B. NC16A domain of BPAg2
Explanation: Bullous pemphigoid is the most common immunobullous disorder and presents with tense vesicles and bullae and pruritus. There has been as association of neurologic disorders, such as Parkinson’s disease and dementia, with bullous pemphigoid. Autoantibodies are most commonly directed against the NC16A domain of BPAg2, also known as BP180 or collagen XVII.
18- Which of the following absorbs ultraviolet radiation?
A. Filaggrin
B. Loricrin
C. Involucrin
D. Urocanic acid
E. Laminin 332
Correct choice: D. Urocanic acid
Explanation: Urocanic acid is a chromophore that absorbs ultraviolet radiation (UVR) in the stratum corneum.This question assesses the examinee’s basic science knowledge of the function of skin proteins and their breakdown products. In the stratum corneum, urocanic acid (choice 4) functions as a chromophore that absorbs UVR and also mediates UV-induced immunosuppression. None of the remaining answer choices absorbs UVR. Urocanic acid is a degradation product of filaggrin (choice 1). Filaggrin cements the keratin filaments composing the stratum corneum; it is mutated in atopic dermatitis and ichthyosis vulgaris. Loricrin (choice 2) is the most plentiful component of the cornified envelope. Involucrin (choice 3), another component of the cornified envelope, is cross- linked to loricrin by transglutaminase 1. Laminin 332 (choice 5), found within the lamina lucida and densa, connects anchoring filaments to collagen VII.
19- Which of the following is NOT a degranulating stimulus for the largest cells seen in the image?
A. Ibuprofen
B. Fentanyl
C. Captopril
D. Vancomycin
E. Polymyxin B
Correct choice: C. Captopril
Explanation: The largest cells in the image are mast cells, which can be identified based on their size and presence of many intracellular granules. Captopril, and ACE-inhibitor, is not a degranulating stimulus for mast cells. The remaining answer choices are all mast cell degranulating stimuli, thus patients with mastocytosis should be counseled to avoid these medications if possible.
20- Which of the following medications is not concentrated in the eccrine glands?
A. Cyclophosphamide
B. Doxycycline
C. Cephalexin
D. Ciprofloxacin
E. Cytarabine
Correct choice: B. Doxycycline
Explanation: 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. Doxycycline does not accumulate in eccrine glands.
21- Which of the following is a conservative and effective treatment for chondrodermatitis nodularis helicis?
A. Mohs micrographic surgery
B. Aggressive cryodestruction with liquid nitrogen
C. TCA peel
D. Cushion pillow support on either side of the lesion to reduce focal pressure
E. Cantharidin application
Correct choice: D. Cushion pillow support on either side of the lesion to reduce focal pressure
Explanation: Chondrodermatitis nodularis helices presents as a tender nodule usually on the helix or antihelix of the ear. It is thought to be a result of pressure to the local, affected area. Multiple treatment modalities have been noted with conservative, effective treatment seen with cushion pillow application to reduce the focal pressure. The other options listed are either too invasive (Mohs, aggressive liquid nitrogen) or are less effective (TCA peels and cantharidin).
22- At any one time, the approximate proportion of hair follicles in anagen phase is:
A. 9%
B. 90%
C. 1%
D. 60%
E. 95%
Correct choice: B. 90%
Explanation: Most (~90%) hair follicles are in anagen (growth) phase. The longer a hair follicle is in anagen phase, the longer the hair can grow. Hairs of the scalp grow approximately 0.4 mm per day, and thus the date of one’s next hair cut can be accurately calculated. Approximately 1% of hairs are in catagen (transitional) phase, whereas ~9% of hairs are in telogen (resting) phase. The remaining answer choices (60% and 95%) are distractors.
23- All of the following are increased in psoriasis EXCEPT:
A. Ornithine decarboxylase
B. Keratin 6
C. Loricrin
D. Involucrin
E. Keratin 16
Correct choice: C. Loricrin
Explanation: Loricrin is the major protein component of the cell envelope. It is decreased in psoriasis. The remaining answer choices are increased in psoriasis.
24- Detection of immunoglobulins, complement, or both at the basement membrane zone in lesional skin by direct immunofluorescence occurs in approximately half of cases of which dermatologic condition?
A. Neonatal lupus erythematosus
B. SLE
C. Erythema multiforme
D. Mixed connective tissue disease
E. Lichen planus
Correct choice: A. Neonatal lupus erythematosus
Explanation: The key diagnostic sign of neonatal lupus erythematosus (NLE) is the erythematous and annular clinical appearance of lesions. The histopathologic findings may be subtle in NLE compared with discoid or subacute cutaneous lupus erythematosus. Direct immunofluorescence testing may be useful in supplementing the histopathologic evaluation. Detection of immunoglobulins, complement, or both at the basement membrane zone in lesional skin by immunofluorescence occurs in approximately half of cases; a negative study does not preclude the diagnosis of NLE syndrome. Clinical and serologic evaluation of both the infant and the mother are important in establishing a diagnosis of NLE syndrome, particularly when histopathologic findings are subtle.
DIF (direct immunofluorescence) of lichen planus is positive in the vast majority, with granular DEJ (dermal-epidermal junction) 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 (systemic lupus erythematosus), 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.
25- A 16-year-old female presents with severe scarring, cystic acne. Which of the following immunologic factors are involved in the pathogenesis of acne?
A. TRPV channels
B. TLR-2
C. MMPs
D. IL-2
E. KLK5
Correct choice: B. TLR-2
Explanation: TLR-2 is a key aspect in the pathogenesis of acne. The other options listed are not key parts of the pathogenesis of acne, some are specifically involved in the pathogenesis of rosacea (KLK5, MMPs and TRPV channels).
26- All of the following locations have apocrine glands except:
A. Internal nares
B. External ear canal
C. Areola
D. Anogenital region
E. Periumbilical region
Correct choice: A. Internal nares
Explanation: Apocrine glands are found in the axillae, anogenital region, external ear canal, eyelids, breast, periumbilical region. Apocrine glands produce an oily fluid rich in triglycerides and fatty acids – subsequent colonization by anaerobic bacteria results in body odor.
Apocrine sweat glands are androgen-dependent for their development and have an unclear function in humans; primary locations are the axillae, anogenital region, periumbilical region and nipples Apocrine glands, whose apical portion (acrosyringium) drains into terminal hair follicles, continuously secrete a sterile odorless viscous fluid that is rich in precursors of odoriferous substances.
27- Subcorneal pustular dermatosis type IgA pemphigus is caused by a defect in what antigen?
A. Desmoglein 3
B. Desmoglein 1
C. BPAg1
D. Desmocollin 1
E. BPAg2
Correct choice: D. Desmocollin 1
Explanation: IgA pemphigus has two types subcorneal pustular dermatosis type which is due to ab to desmocollin 1 and intraepidermal n eutrophilic IgA dermatosis which is due to ab to desmoglein 3 and 1. Sneddon- Wilkinson disease, also known as sub-corneal pustular dermatosis has an unknown etiology. 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.
IgA pemphigus (or immunoglobulin A pemphigus) is an autoimmune blistering disorder. It is also called intercellular IgA dermatosis among other names.
IgA pemphigus has two major subtypes:
1-Subcorneal pustular dermatosis (SPD) type 2- Intraepidermal neutrophilic (IEN) type.
The clinical features of IgA pemphigus include blisters, pustules, erythema, erosions and vegetating lesions. The first signs are flaccid vesicles and pustules. The vesicles and pustules rupture to form erosions and crusted plaques. The eruption tends to follow an annular pattern.
IgA pemphigus appears to favor the trunk, upper and lower extremities, axillae, and groin. Mucosal involvement is infrequent. The exact cause of IgA pemphigus is unclear. IgA autoantibodies bind to desmogleins or desmocollins, the cells responsible for adhesion between cells. In SPD-type IgA pemphigus, the autoantigen is described as desmocollin 1, one of the desmosomal cadherins, the glycoproteins that maintain the shape of a cell. In at least some cases of IEN-type IgA pemphigus, the autoantigens are desmoglein 1, desmoglein 3, and an unspecified transmembrane protein.
28- What is the most abundant amino acid in collagen?
A. Leucine
B. Proline
C. Glycine
D. Hydroxyproline
E. Hydroxylysine
Correct choice: C. Glycine
Explanation: Collagen is composed of 3 chains of amino acids combined into a triple helix configuration. It contains Gly-x-y repeats (glycine is always the 3rd residue). Thus, glycine is the most abundant amino acid in collagen. The remaining answer choices are not the most abundant amino acids in collagen.
- Which of the following medications is concentrated in the eccrine glands?
A. Cyclophosphamide
B. Cytarabine
C. Ciprofloxacin
D. Cephalexin
E. All of the answers are correct
Correct choice: E. 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.
- Which element is necessary for function of matrix metalloproteinases?
A. Iron
B. Nitrogen
C. Manganese
D. Magnesium
E. Zinc
Correct choice: E. Zinc
Matrix metalloproteinases are required for normal tissue architecture and normal turnover of the extracellular matrix. All of them have zinc at the active site and require octahedral binding of calcium ions to maintain structural integrity.
- What is the most important cell for wound healing?
A. Fibroblasts
B. Neutrophils
C. Macrophages
D. Lymphocytes
E. Mast cells
Correct choice: C. Macrophages
Macrophages are the most important cell for wound healing. They secrete TGFs, cytokines, 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 phase 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.
- Which of the following is true in or associated with Apert Syndrome?
A. Secondary to a mutation in FGFR3
B. AR
C. Acne localized to buttocks and thighs
D. Cutaneous/ocular depigmentation
E. Synostoses
Correct choice: E. Synostoses
Apert Syndrome is an AD syndrome secondary to a mutation in FGFR2. Also known as acrocephlosyndactyly, this condition includes synostoses of the hands, feet, back and skull as well as generalized acne. Mosaicism of this gene causes nevus comedonicus. There is associated cutaneous and ocular hypopigmentation.
- What is the most abundant collagen found on fetal skin?
A. Type I Collagen
B. Type II Collagen
C. Type III Collagen
D. Type IV Collagen
E. Type VII Collagen
Correct choice: C. 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.
- Which component of hair is positive for citrulline?
A. Outer root sheath
B. Inner root sheath
C. Cortex
D. Glassy vitreous layer
E. Medulla
Correct choice: B. 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.
- The major protein component of the cornified envelope is:
A. Envoplakin
B. Desmoplakin
C. Plectin
D. Loricrin
E. Transglutaminase
Correct choice: D. 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.
- The most common type of pityriasis rubra pilaris in childhood is type:
A. I
B. II
C. III
D. IV
E. V
Correct choice: D. IV
Type IV, or circumscribed juvenile, accounts for 25% of total PRP cases. The most common type is Type I, classical adult, which accounts for 55% of cases. Types II, III, and V account for less than 10% each.
- Elastic fibers contain the specific amino acids:
A. Lysine and proline
B. Leucine and isoleucine
C. Alanine and phenylalanine
D. Desmosine and isodesmosine
E. Glycine and proline
Correct choice: D. 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.
- Anchoring fibrils are primarily composed of:
A. Type I collagen
B. Type III collagen
C. Type IV collagen
D. Type VII collagen
E. Type II collagen
correct choice: D. 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.
- A child presents with a 1 cm yellow-red nodule on the face. Pathology shows Touton giant cells. What is the most frequent site of extracutaneous involvement in this disease?
A. Eye
B. Lung
C. Bone
D. CNS
E. Visceral
Correct choice: A. Eye
The eye is the most frequent site of extracutaneous juvenile xamthogranuloma. The second most common site of extracutaneous disease is the lungs. Ocular involvement is typically unilateral.
- Keratinocytes are derived from which of the following:
A. Endoderm
B. Mesoderm
C. Ectoderm
D. Neural Crest
E. Bone marrow precursors
Correct choice: C. 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.
- Which epidermal layer do pilar cysts generally not have a:
A. Stratum corneum
B. Stratum granulosum
C. Stratum spinosum
D. Stratum basale
E. Stratum lucidum
Correct choice: B. Stratum granulosum
Pilar cysts do not have a granular layer, they do have all the other layers.
- Fragmentation and/or loss of elastic fibers in not seen in:
A. Cutis laxa
B. Marfan’s syndrome
C. Anetoderma
D. Psuedoxanthoma elasticum
E. Buschke-Ollendorf syndrome
Correct choice: E. 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.
- Which of the following protein plays a major role in wound healing?
A. Uncein
B. Fibronectin
C. Nidogen
D. Entactin
E. Band-6 protein
Correct choice: B. 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.
- Keratinocytes have been shown to secrete all of the following cytokines except:
A. IL-1
B. IL-6
C. IL-8
D. TNF-alpha
E. IL-2
Correct choice: E. IL-2
Keratinocytes have been shown to secrete all of the above cytokines, except IL-2, IL- 4, and IFN- gamma.
- The microflora of pilosebaceous unit consist of which of the following:
A. Pityrosporum ovale
B. Staphylococcus aureus
C. Escherichia coli
D. Pseudomonas aeruginosa
E. Corynebacterium diphtheriae
Correct choice: A. 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.
- Regarding dermal-epidermal junction, which of the following statements is true:
A. There are no anchoring filaments in lamina lucida
B. Lamina fibroreticularis lies above lamina densa
C. Lamina fibroreticularis comprises of anchoring fibrils and the elastic microfibrils
D. Blood vessels cross the dermal-epidermal junction to reach the epidermis
E. Lamina lucida is an electron-dense layer
Correct choice: C. 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).
- Direct immunofluorescence staining of intercellular spaces and the basement membrane zone, in combination, is seen in:
A. Paraneoplastic pemphigus
B. Anti-epiligrin pemphigoid
C. Pemphigus vegetans
D. Pemphigus foliaceous
E. IgA pemphigus
Correct choice: A. 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.
- Keratohyalin granules contain:
A. Desmoplakin
B. Envoplakin and Keratin 6
C. Profilaggrin and loricrin
D. Numerous Golgi apparati
E. Involucrin
Correct choice: C. 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.
- Which eponym describes vestigial lines of pigmentary demarcation?
A. Futcher lines
B. Wallace’s lines
C. Langer’s lines
D. Lines of Blaschko
E. Dermatome
Correct choice: A. Futcher lines
Futcher 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.
- Sebaceous glands are located in each of the following locations except:
A. Nipple
B. Labia minora
C. Palms
D. Eyelids
E. Buccal mucosa
Correct choice: C. 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.
- All of the following pertain to Odland bodies EXCEPT:
A. Contain squalene
B. Are found intracellularly in upper level keratinocytes
C. Discharge their contents into the extracellular space at the junction of the granular and cornified layers
D. Establish a barrier to water loss
E. Mediate stratum corneum adhesion in conjunction with filaggrin.
Correct choice: A. 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.
- Red or blonde hair pigmentation primarily results from:
A. The presence of eumelanin
B. The absence of melanin
C. The presence of pheomelanin
D. The reduced activity of tyrosinase
E. The reduced activity of DOPA dehydroxylase
Correct choice:C. 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.
- Epidermolysis bullosa simplex (EBS), Weber Cockayne type, is caused by what defect?
A. Collagen VII
B. Alpha-6-beta-4 integrin
C. Keratins 1 & 10
D. Keratins 5
E. Plectin
Correct choice: D. 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. CollagenVII 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.
- Which of the following statements about elastic fibers is true?
A. Elastic fibers form 35% of the dry weight of the skin
B. Elastic fibers are 90% elastin wrapped in fibrillin
C. Collagen 1 is mutated in Marfan syndrome
D. Oxytalan fibers run parallel within the superficial papillary dermis
E. Elaunin fibers run perpendicular in thin bands within the reticular dermis
Correct choice: B. 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.
- Eccrine glands are found in all the following areas of the body except:
A. Axillae
B. Palms
C. Labia minora
D. Scalp
E. Cutaneous lip
Correct choice: C. 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.
- When evaluating a foreign body, which substance would be PAS negative and have no bifringence on polarizing microscopy?
A. Silica
B. Talc
C. Zinc
D. Aluminium
E. Wood splinters
Correct choice: D. Aluminium
Starch, cactus spines, and wood splinters are PAS positive. Silica, talc, zinc, and wood splinters are positive for bifringence on microscopy.
- Which of the following statements about the direct immunofluorescence pattern in lichen planus is correct?
A. The DIF is negative in the vast majority of cases
B. Deposition of IgG is within cytoid bodies in the superficial dermis
C. The DEJ deposition is granular
D. Deposition of fibrinogen is within cytoid bodies in the deep dermis
E. There is prominent deposition of IgM within the spinous layer of the epidermis.
Correct choice: C. 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.
- Human sebum is distinguished from lipids of internal organs by the presence of:
A. Cholestrol
B. Cholestrol esters
C. Squalene
D. Wax esters
E. Glycerides
Correct choice: D. 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 humaninternal 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.
- Melanocytes are derived from:
A. Bone marrow
B. Neural crest
C. Mesodermal precursors
D. Endodermal precursors
E. Yolk sac derived
Correct choice: B. 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.
- Apocrine glands are found in all of the following areas of the body except:
A. Axillae
B. Breasts
C. Eyelid
D. Palms
E. Perineum
Correct choice: D. 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.
- Anagen effluvium is best described as:
A. An abrupt transition from anagen to catagen in rapidly dividing hair matrix cells
B. A cessation of mitotic activity in rapidly dividing hair matrix cells
C. An abrupt transition of telogen to anagen in resting hair matrix cells
D. A cessation of mitotic activity in resting hair matrix cells
E. A scarring alopecia affecting only anagen stage follicles
Correct choice: B. 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.
- Which of the following statements is true about eccrine glands?
A. Postganglionic sympathetic fibers with acetylcholine as the principal neurotransmitter
B. Postganglionic sympathetic fibers with norepinephrine as the principal neurotransmitter
C. Postganglionic parasympathetic fibers with acetylcholine as the principal neurotransmitter
D. Postganglionic parasympathetic fibers with norepinephrine as the principal neurotransmitter
E. Postganglionic sympathetic fibers with both norepinephrine and acetylcholine as the principal neurotransmitters
Correct choice: A. 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.
- The strength of a scar:
A. Is 5% at 1 week
B. Is 20% at 3 weeks
C. Is 70% at 1 year
D. All of these options are correct
E. None of these options are correct
Correct choice: D. 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.
- The target for GABEB and bullous pemphigoid is:
A. Type XVII collagen
B. Type VII collagen
C. Laminin 5
D. Integrin subunit B4
E. Type XII collagen
Correct choice: A. Type XVII collagen
The target for GABEB and bullous pemphigoid is type XVII collagen or BPAG2. It is also the target protein in pemphigoid gestationis, CP and linear IgA.
- All mononuclear phagocytic cells in the dermis express:
A. CD3
B. CD6
C. CD34
d. CD68
E. CD20
Correct choice: B. 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.
- How soon does epithelialization begin after a skin wound occurs?
A. Minutes
B. Hours
C. 2 days
D. 4 days
E. 6 days
Correct choice: B. 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.
- Regarding sebaceous glands:
A. These glands are present at birth at their adult size
B. Size of the gland is proportional to the size of the associated hair follicle
C. Are always associated with a hair follicle
D. Are found everywhere on the skin except palms and soles
E. Are unilobular glands
Correct choice: D. 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.
- What is the major function of urocanic acid?
A. Bacteriocidal acid produced by stratum corneum
B. Primarily a UVB filter
C. Primarily a UVA filter
D. Helps degrade free fatty acids
E. Aids in protecting the skin from dermatophytes
Correct choice: C. 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.
- The main collagen component of the basement membrane is:
A. Collagen IV
B. Collagen III
C. Collagen I
D. Tenascin-X
E. Collagen VII
Correct choice: A. 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.
- The main permeability barrier in the lamina densa is:
A. heparan sulfate proteoglycan
B. collagen IV
C. laminin 5
D. nidogen
E. alpha-6-beta-4 integrin
Correct choice: A. heparan sulfate proteoglycan
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.
- The desmosomal connections of the epidermis are dependent on which of the following ions?
A. Iron
B. Zinc
C. Selenium
D. Calcium
E. Sodium
Correct choice: D. Calcium
The desmosomal connections in the epidermis are calcium dependent. The other options are not required for these connections.
- Eulanin fibers:
A. Run parallel in bands within the superficial papillary dermis
B. Run perpendicular from the dermo-epidermal junction within the superficial papillary dermis
C. Run parallel in bands within the reticular dermis
D. Run perpendicular in bands within the deep dermis
E. Run perpendicular in bands within the reticular dermis
Correct choice: C. Run parallel in bands within the reticular dermis
Eulanin 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 withinthe superficial papillary dermis. Elastic fibers turn over slowly in the skin, and are damaged by ultraviolet radiation.
- Meibomian glands are:
A. Eccrine glands localized to the vermillion border of the lips
B. Sebaceous glands found on the areola of the breast
C. Sebaceous glands found on the eyelids
D. Apocrine glands found in the anogenital regions
E. Apocrine glands found on the eylelids
Correct choice: C. 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 foundin 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.
- Which of the following is true about melanosomes?
A. Spheroid melanosomes have concentric lamellae
B. Spheroid melanosomes synthesize brown-black eumelanin
C. Elliptical melanosomes have microvesicular structure
D. Elliptical melanosomes synthesize yellow or red pheomelanin.
E. The melanosomes are positioned after the Golgi apparatus in the secretory pathway.
Correct choice: E. 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.
- Which sebaceous gland is located on the eyelids in association with eyelashes?
A. Montgomery’s tubercles
B. Tyson’s glands
C. Zeis glands
D. Meibomian glands
E. Fordyce’s spots
Correct choice: C. 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.
- Which part of the nose is not innervated by V2 branch of Cranial nerve V?
A. nasal columella
B. nasal ala
C. nasal tip
D. nasal dorsum
E. all sensory of the nose is innervated by V2
Correct choice: C. nasal tip
This is innervated by the anterior ethmoidal branch of V1. The infraorbital nerve of V2 innervates the nasal ala. The nasopalantine branch of V2 innervates the columella.
- Tyrosinase is the enzyme that catalyzes the conversion of tyrosine to DOPA and DOPA to DOPAquinone. The enzyme contains which of the following ions?
A. Zinc
B. Copper
C. Selenium
D. Iron
E. Magnesium
Correct choice: B. Copper
Tyrosinase is a copper containing enzyme that is responsible for the conversion to tyrosine to DOPA and DOPA to DOPAquinone.
- In epidermolysis bullosa simplex, where on the blister does the signal localize on a salt split skin test?
A. Roof
B. Floor
C. Middle
D. Diffuse
E. No localization
Correct choice: A. Roof
In dystrophic EB the signal localizes to the roof of the blister. In junctional EB, the roof has BPAG2 while the floor has type IV collagen.
- The mechanism of action of ipilimumab can be described as
A. Inhibitor of CTLA-4
B. Antibody to CD27
C. Fusion protein binding B7
D. Antibody to CD 8 T cell
E. Inhibitor of CD27
Correct choice: A. 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).
- Desmosine and isodesmosine are typical amino acids found in:
A. Collagen fibers
B. Anchoring fibril
C. Elastic fibers
D. Heparan sulfate
E. Anchoring plaques
Correct choice: C. Elastic fibers
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.
- 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?
A. Epidermal side
B. Dermal side
C. Epidermal and Dermal sides equally
D. In the lamina densa
E. In the anchoring
Correct choice: A. 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.
- 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?
A. Abnormal crosslinking of collagen
B. Abnormal development of elastin fibers
C. Melanocyte death
D. Pigmentation of cartilage
E. Black urine
Correct choice: A. Abnormal crosslinking of collagen
Excess homocystine leads to abnormal crosslinking of collagen, with only ~1/3 of crosslinking activity compared to normal controls . The other listed findings are not features of homocystinuria, though hypopigmentation can be a feature.
- The following is a target in both junctional EB with pyloric atresia and ocular CP:
A. Integrin subunit B4
B. Laminin 5
C. Type VII Collagen
D. Type XVII collagen
E. BPAG2
Correct choice: A. Integrin subunit B4
Integrin subunit B4 is the target for both junctional EB with pyloric atresia and ocular CP.
- Direct immunofluorescence is of no value in the diagnosis of:
A. Neonatal LE
B. Lichen planus
C. Mixed connective tissue disease
D. SLE
E. Erythema multiforme
Correct choice: A. 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.
- 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:
A. Type II collagen
B. Type III collagen
C. Type IV collagen
D. Type VII collagen
E. Type XVII collagen
Correct choice: B. 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 pro
tein in the basement membrane zone.
- The formation of granulation tissue depends on the presence of:
A. Neutrophils
b. Fibronectin
C. Collagen type I
D. Platelets
E. Collagen type IV
Correct choice: B. 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.
- Sebaceous glands:
A. Respond to chemical stimuli such as hormones
B. Respond to cholinergic neural activity, exclusively
C. Respond to adrenergic neural activity, exclusively
D. Respond to both adrenergic and cholinergic stimuli
E. Respond to the local release of cytokines from inflammatory cells
Correct choice: A. 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 glandsare 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.
- The function of glycosaminoglycans/proteoglycans in the dermis is:
A. Regulate water-binding capacity
B. Interact with dermal dendrocytes
C. Facilitate COLVII binding to the anchoring plaques
D. Facilitate mast cell degranulation
Correct choice: A. 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.
- Which one of the following is responsible for maintaining a barrier to water loss in the stratum corneum?
A. Involucrin
B. Filaggrin
C. Loricrin
D. Transglutaminase
E. Odland bodies
Correct choice: E. Odland bodies
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, acomponent 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.
- 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?
A. Smoothened
B. Beta-catenin
C. Keratin 16
D. p53
E. HLA-B27
Correct choice: B. 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.
- Which sebaceous gland is located on the buccal mucosa and vermi lion border of the lips?
A. Montgomery’s tubercles
B. Tyson’s glands
C. Zeis glands
D. Meibomian glands
E. Fordyce’s spots
Correct choice: E. 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, meibomian and Zeis glands are present on the eyelids.
- 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?
A. Nail matrix
B. Proximal nail fold
C. Lunula
D. Eponychium
E. Hyponychium
Correct choice: E. Hyponychium
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.
- The epidermis is comprised of what type of cells?
A. Keratinocytes, Melanocytes, Merkel cells, Langerhan cells
B. Keratinocytes, Endothelial cells, Merkel cells, Langerhan cells
C. Keratinocytes, Melanocytes, Neutrophils, Langerhan cells
D. Keratinocytes, Melanocytes, Merkel cells, Goblet cells
E. Keratinocytes, Endothelial cells, Merkel cells, Goblet cells
Correct choice: A. Keratinocytes, Melanocytes, Merkel cells, Langerhan cells 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.
