Unit III Flashcards
What are the functions of skin?
decoration/beauty barrier vitamin D synthesis water homeostasis thermoregulation insulation/calorie reservoir touch/sensation
What type of melanin produces black to brown pigment?
Eumelanin
*Eutopia!
What type of melanin produces yellow to red-brown pigment?
phenomelanin
Where do light skin melanocytes cluster?
top of nucleus
Where can you find dark skin melanocytes in the cell?
**larger and evenly distributed throughout the cytoplasm
Where do hair follicles originate?
In the subcutaneous fat
Name the four layers of the skin starting from the most superficila layer
stratum corneum
stratum granulosum
stratum spinosum
stratum basalis
What is the stratum granulosum comprised of?
Has Keratohyalin granules and inside granules you have profilaggrin which is a precursor to filaggrin
Where can you find profilaggrin?
In keratohyalin granules
What is the function of filaggrin?
Filaggrin cross-links keratin tonofilaments and is important in the barrier function of the skin. Filaggrin is mutated in dry skin conditions including ichthyosis and atopic dermatitis.
What is the function of the stratum spinosum?
Has a “prickly” or spiny appearance due to desmosome attachments between cells
What are tonofilaments?
protein structures (keratin filaments) that insert into the dense plaques of desmosomes on the cytoplasmic side of the plasma membrane
What is the function of a desmosome?
attaches keratinocytes to each other
What is the function of a hemidesmosome?
attach basal cells firmly to the basal lamina of the dermal
epidermal junction
Difference between desmosome vs hemidesmosome?
desmosome is attachment between cells
hemidesmosomes are attachments to the basal lamina of the dermal epidermal junction (deeper in the cell)
What type of cells are found in the stratum basalis?
keratinocytes - either a single layer cuboidal or columnar
stem cells of the epidermis found here
What is the stratum lucidum?
- a thin, light staining band seen only in thick skin
- cells of this layer no longer have nuclei or organelles
- between the stratum corneum and granulosum
Where in the dermis is the capillary network that is blood supply for epidermis?
the papillary layer
What part of the dermis is the pathway for defense cells?
the papillary layer
What are Meissner’s corpuscles and where are they found?
sensory cells found in the papillary layer of the dermis
Senses **fine touch and tactile discrimination
What part of the dermis contains extensive collagen and elastic fibers that provide strength and flexibility?
The reticular layer
Where in the dermis do epidermal derivatives such as glands and hairs and plays a major role in their development and functioning?
The reticular layer
What part of the dermis has a pathway for major blood vessels arranged specifically to facilitate thermoregulation?
the reticular layer
What part of the dermis has a site of nerve tracts and major sensory receptors?
the reticular layer
Where are Pacinian corpuscles found and what do they do?
In the reticular layer. They sense vibration, pressure and touch
Where are langerhan’s cells found and what do they do?
found in the epidermis and they are essentially the immunologic barrier
“antigen presenting cells of the skin”
what defect causes albinism?
a defect in the tyrosine gene needed for the synthesis of melanin
What is vitiligo?
an autoimmune disease in which antibodies attack melanocytes and you have depigmentation
What are the adnexal structures?
Apocrine glands • Eccrine glands • Hair • Nails • Sebaceous glands -sweat glands
what organs are needed to activate vitamin D3 and 2?
The liver and kidneys
What is the mechanism of getting vitamin D from sun?
UV + 7 dehydrocholesterol = vitamin D
What is bullous pemphigoid?
subepidermal blisters due to an autoimmune response against BP 230 and BP 180 (Type XVII collagen) at HEMIDESMOSOMES
What is Epidermolysis bullosa (EB) ?
a group of inherited bullous disorders characterized by blister formation in response to mechanical trauma.
What is Junctional EB?
blistering due to genetic defects in Laminin 5
What is dystrophic EB?
blistering due to genetic defects in collagen XII
What type of epidermolysis bullosa (EB) leads to mitten hands, flexion contractures, and increased risk in squamous cell carcinomas?
recessive dystrophic EB
What is the thickest layer of the epidermis?
stratum spinosum
What filaments do desmosomes contain?
Contain intracellular keratin filaments (5 and 14)
also contains transmembrane proteins, desmogleins and desmocollins
What is Pemphigus Vulgaris?
intraepidermal blistering due to antibodies against desmoglein 1 and 3
What is epidermolysis bullosa simplex?
onset of blisters shortly after birth due to defects in keratin filaments 5 and 14 (found in desmosomes)
What does the breakdown of filaggrins form?
Forms Natural moisturizing factor (NMF) which binds H2O to keep skin moist
What disorder is caused by defective skin barrier function due loss-of-function filaggrin mutations?
Icthyosis Vulgaris and atopic dermatitis
What is the function of merkel cells and where are they found?
tactile sensation within the epidermis
What is the epidermal rete?
Downward projections of the epidermis that interdigitate with upward projections of the dermal papillae.
Provides strength of adherence, and also increases the surface area between the epidermis and dermis
What is the dermis predominantly comprised of?
collagen fibers, elastic fibers and ground
substance.
What is the significance of collagen I?
Makes up 85% wt of the dermis and is also the major component in bone
What type of collagen comprises a large part of the fetal dermis but is not a major portion of the adult dermis?
collegen III
Where is collagen IV found?
found in high concentration in the “basement membrane zone” which is present in the dermoepidermal junction. Also more prominent around blood vessels (think Ehlers-Danlos syndrome)
What is collagen VII used for?
found in the anchoring fibrils which are used by the
body to attach the epidermis to the dermis.
What type of collagen is synthesized intracellularly within fibroblasts?
procollagen
procollagen consists of how many chains?
3 alpha helical chains
under an electron microscope what is the pattern characteristic of procollagen?
a characteristic pattern of striations with 68 nm intervals
procollagen chains primary consist of what proteins?
Glycine - Proline - Hydroxyproline
What is stasis dermatitis?
Chronic venous insufficiency of the lower extremities associated with lower extremity edema.
What are some complications associated with stasis dermatitis?
Dryness
Itching
Allergic contact dermatitis due to use of topical preparations (i.e. topical antibiotics)
Allergic contact dermatitis (ACD) is found in 58-86% of patients with leg ulcers
Irritant Dermatitis due to wound exudates
How would you treat stasis dermatitis?
Compression Elevation Exercise calf muscles Vascular surgery Topical steroids Avoid allergens
What is the morphology of dermatitis?
Erythematous papules and thin plaques with scale
Where does inflammation take place in dermatits?
Epidermis and dermis
What is the morphology of cellulitis?
Warm, tender, erythematous, patches or plaques
Where does inflammation take place in cellulitis?
dermis and subcutaneous tissue
What is atopic dermatitis?
Common skin disease which may begin at any age, however a majority begin before age 5
Often associated with xerosis (dry skin) and a history of atopy (asthma, allergic rhinitis)
What is the diagnostic criteria for atopic dermatitis?
Must have: Itchy skin + Plus three or more of the following:
- History of involvement of skin creases
- Personal history of asthma or hay fever
- History of dry skin within the last year
- Visible flexural eczema
What is the pathogenesis for atopic dermatitis?
- Barrier disrupted skin
- Filaggrin mutation
- Staphlyococcus aureus acts as a superantigen
- Elevated IgE
- Eosinophilia
- TH2 type cytokine (IL-4, IL-5, IL-10) immune response produced
What’s another word for dermatits?
eczema
What is irritant contact dermatitis?
Non-immunologically mediated reaction resulting from a direct cytotoxic effect
-Either from a single or repeated exposure to the irritant
What is the most common contact dermatitis?
irritant contact dermatitis
What are examples of weak irritants?
o Soap and water
o Skin products (even “baby” and “hypoallergenic”)
o Perfumes
o Wool
o Raw Foods (meat, fruits, or vegetables held while preparing foods)
o Body Secretions (feces, urine, saliva, sweat)
o Friction
What is intertrigo?
an inflammatory condition of skin folds
What are the clinical presentations of adult dermatits?
- involves eyelid and hand dermatitis
- associated with dry skin defect in falaggrin aka ichthyosis vulgaris
- Keratosis vulgaris – lil bumps on back of arm skin and have this more than general population
- Hyperlinearirty of palms – prominent lines
- Ichthyosis vulgaris – defect in falaggrin
What type of dermatitis typically burns more than itches?
irritant contact dermatitis
What is allergic contact dermatitis?
skin condition that requires contact exposure of an allergen, immune response and development of “memory” T cells
The biochemical elicitation of ACD is caused by what molecules?
inflammatory cytokines including TNFα and IL-1.
What is the gold standard testing for ACD?
patch test
What is the most frequent allergen?
nickel exposure 19.5%
What are risk factors for nickel sensitivity?
Young
Female
Ears pierced
What is co-sensitization and give an example
allergy to two allergens which are not structurally related, but are frequently used concomitantly
Bacitracin and Neomycin
What is a drug eruption?
eczematous eruptions/ drug rashes
- Most common type of drug reaction in skin
- Usually cell-mediated type IV hypersensitivity
- Eruption is usually generalized
What is the time course of a drug eruption
usually 7-14 days after starting a new drug (unless the drug is an old medication)
with treatment can resolve in 1-2 weeks
What enhances the risk of a drug eruption?
viral infection
Almost 100% of pts with infectious mononucleosis will get an exanthematous eruption if given ampicillin
-HIV pts are more susceptible to drug eruptions
what is urticaria?
-Hives, wheals
Each individual lesion lasts
What is acute urticaria?
represents an immediate type I hypersensitivity reaction
mediated by IgE antibodies
What layer of skin is affected by urticaria?
No epidermal changes just inflammation in DERMIS so no scale or blisters
Physical features of urticarias
- Dermographism - exaggerated whealing (welting)
- Delayed Pressure Urticaria
- Vibratory Angioedema
- Exercise-induced urticaria
- Cold Urticaria
- Solar Urticaria
- Aquagenic Urticaria
What is the clinical presentation of Seborrheic Dermatitis
- Sharply demarcated patches (thin plaques) with pink or slightly orange-yellow erythema
- Characterized by flaky, “greasy” scales
- Occurs in infancy and post-puberty when sebaceous glands are active
- Occurs in areas rich in sebaceous glands (scalp, face, ears, chest and intertriginous areas).
What diseases have more severe seborrheic dermatitis?
HIV patients
What disease is commonly seen with seborrheic dermatitis?
Parkinson’s disease
What is “cradle cap”
infant seborrheic dermatitis
Begins 1 week after birth and may persist for several months
-Often starts on the scalp and can become confluent with a thick scale covering most of the scalp
-Often seen in the inguinal folds or axillae
What is the pathogenesis of seborrheic dermatitis?
Sensitivity to yeast which can over grow in areas of oil glands and you get a rash that looks like dandruff
What cell type do cherry angiomas affect?
endothelial cells
What are cherry angiomas?
bright, red, smooth-topped papules that are primarily distributed in the truncal region
What is the best treatment option for small cherry angiomas?
Superficial electrodesiccation
What is infantile hemangioma?
Benign endothelial cell neoplasm
What is the most common benign tumor of childhood?
Infantile Hemangioma aka strawberry hemangioma or capillary hemangioma
What is the pattern of involution for a child with infantile hemangioma?
involute slowly at 10% per year
50% resolved by age 5
90% resolved by age 9
What is the first line of treatment for infantile hemangioma (if needed at all) during the growth phase?
Beta blockers
What is the histology of infantile hemangioma?
dermal proliferation of capillary-sized endothelial cell-lined vessels.
What do infantile hemangiomas cells stain with?
placenta associated vascular markers including GLUT-1
What is a port wine stain?
vascular malformation in the endothelum that leads to pink patches.
What is one main difference between port wine stain and hemangiomas?
Port wine stains do not resolve spontaneously and eventually change from a pink patch to thicker purple plaque with nodularity.
does NOT stain with GLUT-1
What is Sturge Weber Syndrome?
systemic abnormality associated with port wine stain aka “facial stain”
10-15% of capillary malformation in a V1 distribution associated with ocular and neurologic abnormalities.
How is port wine stain treated?
with vascular lasers called “pulse dye laser”
What is nevus sebaceus?
A hamartoma the presents as papillomatous, yellow-orange linear plaque on the face or scalp
lesions associated with alopecia
When does nevus sebaceous often occur?
During puberty with all the active sebaceous glands and epidermal hyperplasia busy at work
What are some of the complications associated with nevus sebaceous?
epithelial neoplasms in 10-30% *small cancer risk
epidemal nevus syndrom (neurologic abnormalities)
What are treatment options for nevus sebaceous?
Either observation or surgical excision. Make sure to do excision EARLY!
What is sebaceous hyperplasia?
common benign tumor of oil gland more frequent after middle age
distribution face > trunk > extremities
What treatment for sebaceous hyperplasia?
no treatment needed
electrodessication w/w/o curettage
trichloroacetic acid
liquid nitrogen cryotherapy
What treatment would you recommend with your patient who has recurrent sebaceous hyperplasia?
liquid nitrogen cryotherapy
What are Acrochordons?
skin tags that form in areas of rubbing like neck, axilla, and infra-mammary area
What is the most common form of treatment of acrochordons?
freezing “cryosurgery” with liquid nitrogen
-cut off
What cell type does acrochordon affect?
fibroepithelial layer of the skin
What is dermatofibroma?
Fibrous histiocytoma of the skin that appear as brown, firm papules, and range 3-10 mm in size.
Where are dermatofibromas most commonly found?
Legs
What is a positive dimple (Fitzpatrick) sign indicative of?
Dermatofibroma
What are treatment options for dermatofibroma?
no treatment needed surgical excision (can make make more noticeable)
What is a lipoma?
benign tumor of adipose tissue
What age group are lipomas most common in?
ages 40-60 but can still be seen in children
What type of collagen is a keloid mostly made up of?
collagen III (early/fetal) collage I (late/most abundant)
What is the difference between hypertrophic scars and keloids?
Hypertrophic scars do not growh beyond the boundaries of the original wound
What are treatment options for keloid scars?
topical steroids
intralesional steroids
surgical excision -best for ear keloids
surgery +/- radiation
What are seborrheic keratosis?
benign tumors of the hair follicles
primarily head, neck, and trunk
What is the appearance of seborrheic keratosis?
oval, slightly raised, light brown to black papules or plaques
When is the typical onset of seborrheic keratosis?
fourth or fifth decade with gradual increase in nuber