derm 15% Flashcards
MC cutaneous drug rxn and 2nd MC
MC = IV (morbilliform) 2nd = I (urticaria/angioedema)
how long after exposure does type I rxn occur? type IV?
I- mins-hrs
IV- 2-14days
what disease is lichen planus associated with
HCV
what is the patho of lichen planus
cell-mediated immune response
describe lesions of lichen planus
5 p’s (polygonal, pruritic, planar, purple papules)
with irregular borders + fine scales
on FLEXOR surfaces
what 2 phenomenons are seen in lichen planus
koebners phenomenon
wickhams striae
what is koebners phenomenon
new lesions at sites of trauma
seen in psoriasis + lichen planus
what is wickham striae
fine white lines on skin lesions or oral mucosa in lichen planus
how long does lichen planus last
8-12mo
tx of lichen planus (1st + 2nd line)
1: topical corticosteroid
2: PO steroids, UVB, retinoids
what viral infection is associated w pityriasis rosea
HHV-7
what are the KEY words for pityriasis rose presentation
collarette scaling
cleavage lines
X-mas tree
face is spared
what tests should you get if you suspect pityriasis rosea
RPR- mimics syphilis
how long does pityriasis rosea last
6-12wks
difference btw SJS + TEN
SJS = <10% BSA TENS = >30% BSA
what is the presentation of SJS/TEN
fever + URI sx –> blisters on trunk/face
involves 1+ mucous membrane
+ Nikolsky
what is the patho of erythema multiforme
type IV cutaneous reaction
what is the MC cause of erythema multiforme + what is more common in kids
HSV
mycoplasma more common in kids
how long does erythema multiforme last
2wks
what do the lesions of erythema multiforme look like
target (iris) lesions
dusty-red/violet
pale edematous ring + peripheral red halo
NEG nikolsky
difference btw Erythema multiforme minor + major
minor- no mucous membranes
major- 1+ mucous membranes
when do you use isotretinoins for acne
if nodular or cystic
when do you use topical abx for acne and which can you use
if mild (comedones +/- some papules/pustules) clindamycin - use w benzoyl peroxide
when do you use PO abx for acne and which can you use
moderate (papules + pustules)
doxy, minocycline, emicin, clinda
tx of lice (head/body/pubic) + 2nd line
permethrin- topical
head- shampoo x10min
body/pubic- lotion x8-10hr
2nd line = lindane
what is the cause of erythema toxicum and what age does it present at
neonates (3-5 days old)
immune system activation
what does erythema toxicum look like
pustules on erythematous bases 3-5 days after birth, sparing palms + soles
how long does erythema toxicum last
1-2wks
what is the name for genital warts
condyloma acuminata
tx of warts
podophylin
how do you dx mucosal HPV
whitens w acetic acid application
histology- koilocytic squamous cells
what strains of HPV does gradualism protect against
6, 11, 16, 18
gardasil 9 = + 31, 33, 45, 52, 58
how does urticaria present
blanchable edematous pink papules/wheals/plaques may coalesce dermatographism drier's sign angioedema (painless)
what is dermatographism
new hives caused by local pressure to skin
what is dariers sign
localized urticaria where skin is rubbed
what can you use to tx contact dermatitis
avoid irritants
burrows
what are the ADRs of lindane
shower –> seizure
when is scabies worst
night
what part of the body does scabies affect
everywhere but face + neck
tx of scabies (1st + 2nd line)
permethrin x8-14hr + repeat in 1wk
2nd line- lindane
cause of androgenic alopecia vs alopecia areata
andro- dihydrotestosterone (DHT) excess
areata- immune-mediated (assoc w other autoimmune)
location of androgenic alopecia vs alopecia areata
andro- temporal, mid-front or vertex areas of scalp
areata- smooth, discrete patches
what type of alopecia has exclamation point hairs
areata
is alopecia scarring
no
tx of androgenic alopecia
minoxidil if recent + limited
finasteride (PO)
tx of alopecia areata
local- intralesional injections of corticosteroids
extensive- topical corticosteroids
what causes atopic dermatitis
T cell + IgE mediated
where is atopic dermatitis MC
flexor surfaces
what is nummular eczema
sharply defined coin/discoid shaped
dorm of hands + feet + extensor surfaces
presentation of atopic dermatitis
ill-defined blisters/papules/plaques that dry/crust/scale
dermatographism
tx of atopic dermatitis
topical steroids
topical calcineurin inhibitors (tacrolimus, pimecrolimus)
difference btw topical steroids vs calcineurin inhibitors for atopic dermatitis
calcineurin inhibitors- no skin atrophy but can cause irritation, lymphoma/skin CA
presentation of perioral dermatitis
papulopustules on erythematous base –> confluent into plaques w scales
spares vermillion border
tx of perioral dermatitis
flagyl or e-micin
NO CORTICOSTEROIDS
pathogen involved in seborrheic dermatitis
m.furur
tx of seborrheic dermatitis
selenium sulfide, oral antifungles
cradle cap- baby shampeoo, ketoconazole, topical corticosteroids
what does dyshidrosis look like
tapioca-like vesicles on soles, palms + fingers
tx of dyshidrosis
topical steroids
what kind of virus is molluscum
poxviridae
what does molluscum look like
dome-shaped, flesh-colored
pearly/waxy papules
central umbilication
curd material in center
how long does molluscum last
3-6mo
what organism causes tinea versicolor
m.furfur
what does tinea versicolor look like
hyper/hypopigmented well-demarcated
may coalesce
fine scaling
what diagnostic tools can diagnose tinea versicolor
KOH prep- hyphae + spores (spaghetti + meatballs)
woods lamp- yellow-green fluorescence
tx of tinea versicolor
topical antifungals
MC cause of ringworm
trichophyton
what is tinea capitus
fungal infection of scalp
presentation of tinea capitus
annular, scaling lesions
scarring + alopecia
what skin layer is affected by tinea capitus
stratum corneum
tx of tinea capitus
PO griseofulvin (1st) PO terbinafine, itraconazole or fluconazole
tx of tinea pedis/cruris/corporis
topical antifungal
PO griseofulvin if failed
what toe is MC affected by onychomycosis
big toe
tx of onychomycosis
itraconazole + terbinafine
what is vitiligo
autoimmune destruction of melanocytes
where is vitiligo MC
dorsum of hands axilla face fingers folds genitals
tx of vitiligo
localized- topical steroids, calcineurin inhibitors
disseminated- phototx
what is the MC type of impetigo
nonbullous
what causes nonbullous impetigo
s.aureus (MC)
GABHS (2nd MC)
what is the keyword for nonbullous impetigo
honey-colored crust
what causes bullous impetigo
S.aureus MC
who usually gets bullous impetigo
newborns
what does bullous impetigo look like
vesicles –> large bullae –> rupture –> thin varnish-like crust
fever + diarrhea
what causes ecthyma
GABHS MC
what does ecthyma look like
ulcers heal w scarring
what is the tx for nonbullous impetigo, bullous impetigo and ecthyma
mupirocin (bactroban) 1st
keflex if systemic (fever) or extensive
what causes miliaria
blocked sweat glands
what are the 3 types of miliaria (superficial to deep) and their differences
crystallina- tiny, friable, clear vesicles
rubra- severely pruritic papules
profunda- flesh-colored
what causes milia
keratin retention in dermis
what does milia look like
pearly white-yellow papillose on cheeks, forehead, chin + nose
how long does milia last
1-3mo of age
what is another name for staph scalded skin
ritter disease
what causes staph scalded skin
exfoliative exotoxins from s.aureus
who MC gets staph scalded skin
<5yo
presentation of staph scalded skin
malaise/fever/skin tenderness –> blanching erythema starting around mouth –> diffuse
worst in flexor areas + around orifces
–> sterile flaccid blisters in mechanical stress areas
positive nikolskys
–> desquamative phase
tx of staph scalded skin
nafcillin or oxacillin +/- clinda (1st line)
