Dermatology Flashcards
Layers of epidermis
"Come Lets Get Sun Burned" Stratum corneum stratum lucidum (palms and soles) stratum granulosum stratum spinosum stratum basale
then dermis - with blood vessels
Melanocytes
melanin producing cells
locked in stratum basale
responsible for skin, eye, hair color
neurocrest cell origin
Atopic dermatitis
“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
Atopic dermatitis treatment
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
Pathophysiology and assoc treatments for Acne
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
Verrucae
Common warts - HPV 2, 4
Hands - vulgarism
Genitals - condyloma acuminatum
Tx: salicylic acid - OTC
Imiquiniod= increase IFN production
liquid nitrogen
Melanocytic nevus
nevus cells
benign
most appear first 2 decades
congenital mole - increase risk of melanoma
Allergic contact dermatitis
type IV - delayed, CD4 mediated
nickel allergy, poison ivy (linear pattern)
Psoriasis
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
Seborrheic keratosis
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
Albinism
lack of melanin pigment d/t lack of tyrosinase enzyme
normal number of melanocytes, decreased melanin production
Vitiligo
areas of body w/ complete depigmentation
decreased number of melanocytes
autoimmune w/ genetic factors - possible viral involvement, oxidative stress
Melasma
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
Impetigo
S. aureus, S. pyogenes - highly contagious
honey colored crusting lesion found around lips, nose of children
tx: topical mupirocin, oral dicloxacillin, cephalexin
Cellulitis
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
Necrotizing fasciitis
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
Staphylococcal scalded skin syndrome
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
Hairy leukoplakia
White patches on side of tongue, painless plaques - can’t be scrapped off
EBV in immunocompromised pts (HIV)
5-15% precancerous
Pemphigus vulgaris
"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
Bullous pemphigoid
“BPH” bullous pemphigoid = hemidesmosomoes
Ab against hemidesmosomoes
Eosinophils within blister
Less severe than pemphigus bulgars, negative nikolsky sign, no oral lesions
Dermatitis herpetiformis
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
Erythema multiforme
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
Stevens-Johnson syndrome
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)
Lichen planus
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
Actinic keratosis
Growths of thick, scaly, crusty skin
Untreated lesions up to 20% risk of squamous cell carcinoma - fair skinned, sun exposure
Tx: 5-fluorouracil, cryoablation
Acanthosis nigricans
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
erythema nodosum
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
Pityriasis rosea
begins as herald patch (2-10 cm red oval)
generalized rash - christmas tree distribution
resolves in 4-6 weeks - sunlight helps
