Dermatology

Question 1

Layers of epidermis

Answer 1

"Come Lets Get Sun Burned"
Stratum corneum
stratum lucidum (palms and soles)
stratum granulosum
stratum spinosum
stratum basale

then dermis - with blood vessels

Question 2

Melanocytes

Answer 2

melanin producing cells
locked in stratum basale
responsible for skin, eye, hair color

neurocrest cell origin

Question 3

Atopic dermatitis

Answer 3

“eczema” - “itch that rashes”
pruritic
skin flexures - antecubital fossa, behind knees

assoc w/ other atopic dz: asthma, allergic rhinitis

worse in daily bathing infants, dry months - winter

Question 4

Atopic dermatitis treatment

Answer 4

Mild: moisturizing soap, add emollient
Calcineurin inhibitors - tacrolimus or pimecrolimus
Topical steroids - flare ups, prn
Abx for open lesions - cover S. aureus and strep

anti histamines
Leukotriene inhibitors - assoc w/ atopy

UV light therapy

Severe: systemic steroids
Very severe: methotrexate, cyclosporine, azathioprine - last result, adult cases

Question 5

Pathophysiology and assoc treatments for Acne

Answer 5

Hyperkeratosis - Topicals: vit a analogs: retinoid acid, tretinoin; oral - isotretinoin - severe

Sebum overproduction - isotretinoin, spironolactone - decrease androgens, CHF w/ acne, OCPs

Propionibacterium acnes proliferation : erythromycin, tetracycline, doxycycline, minocycline; topical: clindamycin; inhibit growth with benzoylperoxide (OTC)

Inflammation: steroids - can induce acne if too frequently used

Question 6

Verrucae

Answer 6

Common warts - HPV 2, 4
Hands - vulgarism
Genitals - condyloma acuminatum

Tx: salicylic acid - OTC
Imiquiniod= increase IFN production
liquid nitrogen

Question 7

Melanocytic nevus

Answer 7

nevus cells
benign
most appear first 2 decades

congenital mole - increase risk of melanoma

Question 8

Allergic contact dermatitis

Answer 8

type IV - delayed, CD4 mediated

nickel allergy, poison ivy (linear pattern)

Question 9

Psoriasis

Answer 9

overproduction of new skin cells
Papules and plaques of silvery scale

knees and elbows

micro: increased stratum spinosum, decreased stratum granulosum
- parakaratosis - retained nuclei in stratum corner

Auspitz sign - bleeding spots where scale scraped
Nail pitting

Tx: moisturizers, emolients
topical: steroids, tar containing creams, Vit D analogs, retinoids
phototherapy
Oral: methotrexate, cyclosporine, systemic retinoids
Biologics: adalimumab, etanercept, infliximab

Systemic steroids not used, cause rebound flare

Question 10

Seborrheic keratosis

Answer 10

common benign neoplasm - older, cosmetic
flat, warty, greasy, pigmented (tortoise shell), pasted or stuck on appearance

micro: squamous epithelial proliferations w/ keratin-filled cysts - horn cysts

Question 11

Albinism

Answer 11

lack of melanin pigment d/t lack of tyrosinase enzyme

normal number of melanocytes, decreased melanin production

Question 12

Vitiligo

Answer 12

areas of body w/ complete depigmentation
decreased number of melanocytes
autoimmune w/ genetic factors - possible viral involvement, oxidative stress

Question 13

Melasma

Answer 13

dark discoloration common in pregnant women, OCP use, hormone replacement

d/t stimulation of melanocytes by estrogen and progesterone - hyper pigmented macule

spontaneously resolves over several months

Question 14

Impetigo

Answer 14

S. aureus, S. pyogenes - highly contagious
honey colored crusting lesion found around lips, nose of children

tx: topical mupirocin, oral dicloxacillin, cephalexin

Question 15

Cellulitis

Answer 15

infection of dermis

S. pyogenes, S. aureus

Tx non MRSA: oral dicloxacillin, cephalexin - non purulent
tx of MRSA: oral trimethoprim/sulfamethoxazole, clindamycin - lots of pus

Question 16

Necrotizing fasciitis

Answer 16

infection involving deeper layers of skin and subcutaneous tissues

• spread across the fascial plane
• tenderness extends beyond visible area of cellulitis, crepitus (anaerobic production of methane)

caused by anaerobic bacteria and S. pyogenes

tx: immediate surgical debridement, IV carbapenem + clindamycin

Question 17

Staphylococcal scalded skin syndrome

Answer 17

Epidermolytic exotoxins A and B - destroy keratinocyte attachments in the stratum granulosum

Fever, generalized erythematous rash w/ sloughing of upper layers of epidermis in newborns and children

Tx: nafcillin, oxacillin, vancomycin

Question 18

Hairy leukoplakia

Answer 18

White patches on side of tongue, painless plaques - can’t be scrapped off

EBV in immunocompromised pts (HIV)

5-15% precancerous

Question 19

Pemphigus vulgaris

Answer 19

"DAMN is a Vulgar word"
Desmosomes
Acantholysis
Mouth ulcers
Nikolsky sign

Ab against desmosomes
Painful blisters, flaccid (wrinkly, droopy), positive nikolsky sign (separation of epidermis w/ stroking), oral lesions

Punch bx: direct immunofluorescent staining = reticular (fishnet) pattern (Ab), pacantholysis - loss of desmosomes

Question 20

Bullous pemphigoid

Answer 20

“BPH” bullous pemphigoid = hemidesmosomoes

Ab against hemidesmosomoes
Eosinophils within blister
Less severe than pemphigus bulgars, negative nikolsky sign, no oral lesions

Question 21

Dermatitis herpetiformis

Answer 21

Chronic blistering dz

Appearance of HSV, intensely pruritic papule and vesicles

Direct immunofluorescent = deposits of IgA in dips of dermal papillae

Assoc w/ celiac dz and worsens w/ gluten ingestion

Question 22

Erythema multiforme

Answer 22

Deposition of immune complexes in superficial microvasculature of skin and oral mucous membranes - follows infection or drug exposure

mild rash to severe life threatening condition (related to stevens johnson sn)

macules, papules, vesicles, target lesions, pruritic

Question 23

Stevens-Johnson syndrome

Answer 23

Cells death leading to separation of epidermis from dermis

Hypersensitivity reaction - skin and mucous membranes

Fever, bulla formation, necrosis, sloughing of skin

High mortality rate

Toxic epidermal necrolysis - 30% body surface sloughing

Cause: anti-seizure drugs, sulfa drugs, penicillins, allopurinol (outlier drug)

Question 24

Lichen planus

Answer 24

autoimmune process w/ unknown trigger

Ps: pruritic, purple, polygonal papules and plaques

Micro: sawtooth pattern of lymphocytes at dermal-epidermal junction

assoc w/ hep C

Question 25

Actinic keratosis

Answer 25

Growths of thick, scaly, crusty skin

Untreated lesions up to 20% risk of squamous cell carcinoma - fair skinned, sun exposure

Tx: 5-fluorouracil, cryoablation

Question 26

Acanthosis nigricans

Answer 26

Brown to black, poorly defined, velvety hyperpigmentaiton of skin

d/t hyperplasia of stratum spinosusm

lateral and posterior folds of neck, axilla, groin

assoc w/ hyperinsulinemia, visceral malignancies

Question 27

erythema nodosum

Answer 27

12-20 yo

inflammatory lesions of subcutaneous fat

tender, red nodules on b/l shins

assoc w/ sarcoidosis, histoplasmosis, coccidioidomycosis, TB, leprosy, group A strep (strep pharyngitis) infections

resolves spontaneously w/in 3-6 weeks

Question 28

Pityriasis rosea

Answer 28

begins as herald patch (2-10 cm red oval)
generalized rash - christmas tree distribution

resolves in 4-6 weeks - sunlight helps