derm

Question 1

layers of epidermis?

Answer 1

surface to base (Californians Like Girls in String Bikinis):
Corneum (keratin)
Lucidum 
Granulosum
Spinosum (desmosomes)
Basale (stem cells)

Question 2

zonula occludens?

Answer 2

= tight junction
apical side of epithelial cell
claudins and occludins
prevents paracellular solute movement

Question 3

zonula adherens?

Answer 3

= adherens junction
below zonula occludens
connects actin cytoskeletons of adjacent cells with cadherins (Ca dependent)

** loss of E-cadherin –> metastasis

Question 4

macula adherens?

Answer 4

= desmosomes
below zonula adherens
keratin interactions –> structural support

** autoAbs –> pemphigus vulgaris

Question 5

epithelial cell gap junctions?

Answer 5

made up of connexons

allow communication

Question 6

epithelial cell integrins?

Answer 6

at basolateral surface

proteins that bind to collagen and laminin in basement membrane

Question 7

hemidesmosomes?

Answer 7

at basolateral surface
connect keratin of basal cells to basement membrane

** autoAbs –> bullous pemphigoid

Question 8

increased thickness of stratum corneum?

Answer 8

hyperkeratosis

seen in psoriasis, calluses

Question 9

hyperkeratosis with retention of nuclei in stratum corneum?

Answer 9

parakeratosis

seen in psoriasis

Question 10

epidermal accumulation of edematous fluid in intercellular spaces?

Answer 10

spongiosis

seen in eczematous dermatitis

Question 11

separation of epidermal cells?

Answer 11

acantholysis

seen in pemphigus vulgaris

Question 12

epidermal hyperplasia (increased stratum spinosum)?

Answer 12

acanthosis

Question 13

decreased melanin production, normal melanocyte number?

Answer 13

albinism
defect in tyrosinase activity or tyrosine transport; or failure of neural crest cell migration in development

** increased risk of skin cancer

Question 14

preggo with hyperpigmented areas on face?

Answer 14

melasma (chloasma)

assoc with preg or OCP use

Question 15

autoimmune destruction of melanocytes?

Answer 15

vitiligo

Question 16

melanocytic nevus?

Answer 16

common mole

** intradermal nevus: papular; junctional nevus: flat

Question 17

epidermal changes in psoriasis?

Answer 17

increased stratum spinosum and stratum corneum

decreased stratum granulosum

Question 18

rhinophyma?

Answer 18

bulbous deformation of nose

from chronic inflammatory changes of rosacea

Question 19

sudden appearance of multiple seborrheic keratoses?

Answer 19

Leser Trelat sign = sign of underlying malignancy

- GI, lymphoid

Question 20

honey colored crusting?

Answer 20

impetigo
S aureus or S pyogenes
(bullous usually S aureus)

Question 21

well-defined demarcation b/w infected and normal skin?

Answer 21

erysipelas
upper dermis and superficial lymphatic involvement
S pyogenes

Question 22

MC organism in skin abscess?

Answer 22

MRSA

Question 23

bullae, purple skin, crepitus?

Answer 23

nec fasc

anaerobes or S pyogenes

Question 24

fever and generalized erythematous rash with sloughing?

Answer 24

staph scalded skin

** exotoxin destroys keratinocyte attachments in stratum granulosum ONLY

Question 25

white painless NON-scrapeable tongue plaques?

Answer 25

hairy leukoplakia

EBV

Question 26

flaccid intraepidermal bullae, oral involvement, Nikolsky +?

Answer 26

pemphigus vulgaris - potentially fatal
IgG Abs to desmoglein (anti-desmosome)
immunofluorescence: Abs in reticular pattern around epidermal cells

** bullae caused by acantholysis

Question 27

tense blisters, no oral involvement, Nikolsky -?

Answer 27

bullous pemphigoid - not as bad as vulgaris
IgG Abs to hemidesmosomes
immunofluorescence: Abs in linear pattern at epidermal/dermal junction

** blisters contain eosinophils

Question 28

pruritic papules, vesicles, bullae; often at elbows?

Answer 28

dermatitis herpetiformis
IgA deposits at tips of dermal papillae
assoc with celiac

Question 29

multiple lesion types, including target lesions?

Answer 29

erythema multiforme
infections: mycoplasma, HSV
drugs: sulfa, beta lactams, phenytoin
cancer
autoimmune dz

Question 30

SJS/SJS-TEN/TEN?

Answer 30

SJS < 10% BSA
SJS-TEN: 10-30%
TEN > 30%

Question 31

small rough red/brown papules/plaques?

Answer 31

actinic keratosis
premalignant –> squamous cell ca
caused by sun exposure

Question 32

painful lesions on anterior shins?

Answer 32

erythema nodosum
subQ fat lesions

** assoc with sarcoid, coccidio, histo, TB, strep, leprosy, Crohn

Question 33

pruritic, purple, polygonal, planar papules and plaques?

Answer 33

lichen planus
mucosal involvement: Wickham striae (white lines)
sawtooth lymphocytic infiltrate at dermal-epidermal junction

** assoc with HCV

Question 34

UVA vs UVB?

Answer 34

UVA –> tanning, photoaging
UVB –> sunburn

UV radiation –> DNA mutation, keratinocyte apoptosis

Question 35

pink pearly nodule, rolled borders, central crusting/ulceration?

Answer 35

basal cell carcinoma
MC skin cancer
locally invasive, rare mets

** palisading nuclei

Question 36

ulcerative red lesions with frequent scale; sun-exposed areas?

Answer 36

squamous cell carcinoma
2nd MC skin cancer
locally invasive, LN spread possible, rare mets

• • keratin pearls on histo
• • assoc with arsenic exposure

Question 37

melanoma marker?

Answer 37

S-100

Question 38

melanoma mutation?

Answer 38

BRAF kinase activating mutation

** BRAF V600E - can try vemurafenib (BRAF kinase inhibitor)