11. Dermatology

Question 1

Impetigo

• tx
• what if pen allergix

Answer 1

amox/1st gen cephalosporin

clinda

Question 2

Acne tx approach

Answer 2

pyramid:

refractorry: isoreitinoin (get UPreg)
severe: Doxy/Erythromycin
inflamed pustulses: benzyoyl peroxide
comedones: retinoids, topical.

Question 3

what 2 fungal infxns need oral tx?

• what if don’t tx?
• danger of orals?

Answer 3

Hair/Nails needs orals x several months:

• tinea capitis–griseofulvin
• onychomycosis–terbinafine

-permanent hair loss if don’t tx tinea capitis

long term oral can have hepatotox. Therefore, must confirm dx with KOH before starting oral tx

Question 4

contact dermatitis:

2 forms

Answer 4

irritant and allergic

irritant: direct toxic chemical effect on skin (occupation related chemical)
allergic: nickel, poison ivy, latex, etc

Question 5

what is stasis dermatitis

Answer 5

people with leg edema (venous insuff), get leg flaking, erythema, brown discoloration, scaling.

Don’t bx, as non-healing ulcer may occur. Venous stasis ulcer may also be present.

Question 6

pemphigus vs pemphigoid

• sxs
• dx
• tx
• population

Answer 6

pemphigus:
\+ nikolsky's, oral involvement
bx shows tombstones
steroids, MMF, Rituximab, life threatening
Age 30-50

pemphigoid:
- nikolsky's, no oral
bx IF shows Ab to dermal-epidermal jxn
Age 70-80
steroids

Question 7

Bullous skin diseases (4 to know):

Answer 7

1. pemphigus
2. pemphigoid
3. dermatitis herpetiformis
4. porphyria cutanea tarda

Question 8

porhyria cutanea tarda

• when to suspect
• how to dx
• tx

Answer 8

• when you see bullae on skin-exposed surfaces only
• Dark urine. Flouresces ‘coral red’ under Wood’s lamp. (urine uroporphyrins)

tx: avoid sun, Etoh , other triggers.

Question 9

seborrheic dermatitis

• what is it
• tx

Answer 9

‘super-dandruff.’ (not seborrheic keratosis)

-cradle cap included

selenium shampoo

Question 10

Psoriasis

-tx

Answer 10

1st step: UV light

topical steroids in flares

Question 11

pityriasis rosea

• what is this
• what can it be confused with
• tx

Answer 11

• herald patch, progressing to salmon-colored lesions.
• can look like rash of syphilis. (syphilis has hands/soles, pityriasis does not)
• steroids, self limiting 6 weeks

Question 12

drug rash

• how long after drug exposure
• appearance

Answer 12

• 4-14 days after exposure

- pink, morbilliform

Question 13

Pt with target-shaped lesions on palms, soles.

Think what other than erythema multiforme?

Also, what are causes of erythema multiforme? (3)

Answer 13

-syphilis

1. drug (esp cephalosporins)
2. HSV
3. mycoplasma

Question 14

erythema multiforme/SJS/TEN

-what drugs can cause? (think 4 categories)

Answer 14

• sulfa
• PCN
• NSAIDs
• anticonvulsants

Question 15

SJS vs TEN

-difference, how to know

Answer 15

2 things: body surface area, and Bx

SJS: <10% BSA, Bx shows basal cell degeneration

TEN: >30% BSA, full thickness necrosis

Bx also will find out SSSS

Question 16

Pt with SJS/TEN: other than getting bx, do what (3)

Answer 16

• remove ALL meds, including steroids (can worsen!).
• Admit to burn unit
• give Clinda

Question 17

SJS/TEN: how many days after drug exposure?

Answer 17

no correlation, could be days or weeks

Question 18

melanoma

• mnemonic
• what to do if suspect?

Answer 18

ABCDE
asymmetry
border
color
DIAMETER >5mm
evolution

Wide excisional bx, punch bx if on face and suspicion low

Question 19

Seborrheic keratosis vs melanoma

Answer 19

seborrheic keratosis (stuck on age spots, look like ugly moles)

-if present long time, unchanged, it is SK. however, if new or changing, do bx to r/o melanoma.

Question 20

actinic keratosis: what is dz spectrum?

-do what for actinic keratosis

Answer 20

actinic keratosis
Bowen’s dz (CIS)
SCC

pre-SCC, so do Bx. Do local ablation. If CIS/Bowen’s resect. Can also do 5-FU, imiquimod

Question 21

Pt says they had “SCC that went away on its own” on his hand, think what

Answer 21

Keratoacanthoma. looks like SCC but grow and regress spontaneously.

If you see it, do resection like SCC

Question 22

Pt with patchy depigmentation on skin:

• what dx to think:
• how to dx
• tx

Answer 22

1. tinea versicolor.
   -KOH prep–sphagethi meatballs
   selenium shampoo.
2. vitiligo
   - dx with Woods lamp
   - steroids and UV light

Question 23

Tuberous sclerosis:

-skin findings (3)

Answer 23

1. shagreen patch (raised collagen)
2. sebaceous adenomas (funny looking acne)
3. ash-leaf macules (hypopigmented, use Woods lamp)

Question 24

salmon colored rash, think what dx

-tx

Answer 24

pityriasis rosea

• always check RPR
• tx with topical steroids, 6 weeks self limiting

Question 25

Patchy alopecia: dx approach?

Answer 25

Make sure exisiting hair same length (otherwise trich). Think tinea capitis–do KOH prep.

If KOH-, think lupus, get ANA.

Question 26

Eczema

-first tx?

Answer 26

topical steroids (hydrocortisone)

benadryl is adjunct

Question 27

Post-strep GN

-what is time frame after infection?

Answer 27

3-6 weeks after impetigo

1-2 weeks after strep pharyngitis

Question 28

Hypersensitivity types 1-4?

Answer 28

1. immediate Allergic reaction
2. Ab target antigens on tissue surfaces. eg Graves, Myasthenia gravis, ABO incompat. no rashes.
3. Ag/Ab complexes, depositing on tissues. eg RA, SLE, reactive arthritis
4. delayed, T cells. eg contact dermatitis

Question 29

key words:

• Ab against hemidesmosomes
• Ab against desmoglein
• neutrophilic abscess in dermal papillae

Answer 29

• pemphigoid
• pemphigus
• dermatitis herpetiformis