Dermatology Flashcards
1
Q
contact derm
A
- irritant: nonimmune modulated skin irritation cause by skin inj, direct cytotoxic effects, or cutaneous inflamm from contact with irritant
- allergic: type IV, T-cell mediated, delayed hypersensitivity rxn from foreign substance
- MC: poison ivy, nickel, fragrances
- sxs: not painful but red and itchy, onset after contact with irritant or allergen, distribution patterns from irritant or allergen
- signs: scaly occuring on thin areas of skin (flexural surfaces, eyelids, face, anogenital region)
- acute = erythema, vesicles, bullae; chronic = lichenification with cracks and fissures
- dx: determine if problem resolves with removal of substance
- tx: localized = mid-or high-potency topical steroids (triamcinolone
- if >20% of BSA, systemic steroids recommended with resolution in 12-24h
- 5-7d of prednisone
2
Q
staph toxic shock syndrome etiology sxs
A
- result of capillary leak and damage from inflamm cytokines induced by GAS; s. aureus strains produce exotoxins, through isolation not necessary for dx
- caused by TSS toxin-1, 50% cases = menstrual related; nonmenstural are associated with surgical or c-section wound infxns, breast aug, septorrhinoplsty, hysterect, osteomyelitis, lipo, bunionectomy, bone pinning, burns
- onset of surg cases within 2 d postop up to 65d postop, may occur with deep seated infxns or bacteremia
- sxs: fever, flu-like, abd pain, V/D, dizziness, rash, sore throat
- signs: fever >102, hoTN, macular erythroderma, desquammation of palms or soles, decreased UOP, cyanosis, periph edema, somnolence, confusion, irritability, agitation, hallucinations
- complications: irreversible resp failure, coag defects, cardiac arrhythmias, cardiomyopathy
3
Q
staph toxic shock syndrome dx and tx
A
- dx: pelvic exam, CK 2xULN, BUN or SCr >2x ULN, UA shows pyuria in absence of UTI, bili or AST/ALT >2x ULN, CBC platelets <100k, blood and CSF cx, serologic tests for RMSF, leptospirosis, measles
- to diagnose: fever, hoTN, diffuse erythema, desquammation, involves at least 3 organ systems (renal dysfn, coagulopathy, liver dysfn, ARDS, macular rash, soft tissue necrosis (nec fasc, myositis, gangrene)
- tx: supportive, IVF replacement, pressors if needed, debridement (in surg pts infected wounds may not appear infected dt dec inflamm response), abx (IV clinda) PLUS vanco x2wk
- health maintenance: nasal cxs (if pos, tx with topical mupirocin for proph)
- prognosis: death-associated TSS occurs within first days of admission but occurs as late as 2wks after admission
4
Q
Basal cell carcinoma
A
- MC cutaneous neoplasm, 85% occur on head or neck
- RF: fair skin, sun exposure, male gender
- signs: firm, round, and pearly or waxy papule or nodule on head or neck (PEARLY PINK PAPULES), margin telangiectasia (rolled border), fragile (bleed and scab)
- dx: shave bx, scoop or punch for sclerosing or flat superficial BCC
- tx: currettage, cryotx, excision, Mohs (gold standard), imiquimod, 5% FU, photodynamic radiation
5
Q
Cellulitis
A
- 80% caused by s. aureus, or GABHS, pasteurella multocida if cat or dog bite
- MRSA RF: abx, prolonged hosp, surg infxn, ICU, hemodialysis
- usually lower leg, deeper than erysipelas, ill-defined border, acute infxn of skin involving the dermis and subcut tissues
- sxs: hx break in skin, erythema, warmth, TTP, pain, edema, indistinct margins, bulla → necrosis, sloughing and erosion, firm, tender induration, usually no fluctuance, +/- fever, crepitus, streaks of lymphangitis
- dx: asp if fluctuant, blood cx if febrile, rubor, calor, tumor, dolor
- tx: outpt nonpurulent → tx for GAS (PCN, dicloxacillin, cefazolin, cephalexin, clinda)
- outpt purulent → tx for MRSA (clinda, bactrim, FQ, tetra)
- inpt: hosp pts who are immunocomp, IV abx until infxn sxs improve, then oral abx x2wk (IV naf, IV cefazolin, IV vanco)
6
Q
Melanoma
A
- MC: cancer 25-29yo, number one COD d/t skin cancer
- RF: fair, sun exposure, FHx, xeroderma pigmentosum, old, lots of moles, dysplastic nevus syndrome, giant congenital nevi
- MC types: superficial spreading, flat macule or slightly raised discolored plaque with irregular borders, on trunk in men and legs in women
- sxs: asymmetry, irreg border, varied color, diameter >6mm, evolving size, shape, sxs
- dx: excision bx (shave and punch less accurate), lymph node dissection
- tx: complete full skin depth excision using margins determined by Breslow depth
- Breslow depth: tumor thickness from granular layer of ep to pnt of deepest invasion
- 5mm: in situ lesions
- 1-2cm: invasive lesions
- most important indicator of prognosis = depth of invasion
7
Q
burns classifications
A
- first degree → MCC is overexposure to sunlight and breief scalding, only involves epidermis, painful but doesnt blister (resolves in 48-72hrs), erythema and minor micro changes
- tx: heals uneventfully, damaged skin peels off in 5-10d, no scarring
- second degree (partial thickness) → involves all of epidermis and some corium or dermis, extremely painful with weeping and blisters
- superficial → blister formation (increase in size)
- tx: most heal with expectant management w/ minimal scarring in 10-14d
- deep → reddish appearance or layer of whitish, nonviable dermis firmly adherent to remaining viable tissue
- tx: excise and graft (heal over 4-8wks)
- complications: conversion to full thickness burn by infxn
- superficial → blister formation (increase in size)
- third degree (full thickness) → prolonged exposure to heat, involvement of fat and underlying tissue; leathery, painless, nonblanching (white, dry, waxy)
- dx: lack of sensation in burned skin, lack of cap refill, leathery texture
- tx: requires skin grafting and escharotomy, no potential for reepithelialization
- fourth degree → affects underlying soft tissue
- Rule of nine: ant and post trunk each are 18%, each lower extrem is 18%, each upper extrem is 9%, head is 9%
- parkland or baxeter formula → 3-4ml/Kg/% burn of lactated ringers (half given during first 8 hrs, remaining half given over subsequent 16hrs)
8
Q
burn zones and infections
A
- MC species in burn-wound = pseudomonas and MRSA
- zone of coagulation: most severely burned portion and is typically in center of the wound, likely needs excision and grafting
- zone of stasis: peripheral to zone of coag with variable degrees of vasoconstriction and resultant ischemia, much like second-degree burn
- zone of hyperemia: which heals with minimal to no scarring and is most like a superficial or first-degree burn
- appropriate resuscitation and wound care may help prevent conversion to a deeper wound but infxn or suboptimal perfusion may result in increase in burn depth
- burn wounds evolve over 48-72h after injury
- one of the most effective ways to determine burn depth is full-thickness bx but this has several limitations (procedure painful and potentially scarring, accurate interpretation of histopathology requires specialized pathologist and may have slow turn-around times)
- prognosis: directly related to extent of injury both size and depth
9
Q
discharge
A
- depending on location and onset after surgery, a wide differential must be considered, which includes the following: paronychia, pressure or decubitus ulcers
10
Q
erythema multiforme
A
- delayed-type hypersensitivity rxn to infxn or drugs, adults 20-40, infectious causes = HSV 1 or 2, M pneumo, fungal
- meds: barbiturates, hydantoins, NSAIDs, PCN, phenothiazines, sulfonamides
- sxs: acute, polymorphous eruption of macules, papules, and “target or iris lesions” without scaele = round shape, 3 concentric zones, itching or burning at site
- signs: sharply demarcated red or pink macules → papular → plaques , central portion becomes darker red, brown, dusky, or purpuric, crusting or blistering of center, symmetrically distrib, spreads distal to prox, minimal mucous memb involvement
- dx: <10% of body surface area
- tx: tx existing infxn or dc drug (mild = no tx; recurrent = acyclovir continuously)
- prognosis: resolves spontaneously in 3-5wks without sequelae, may recur
11
Q
Stevens-Johnson syndrome
A
- most often caused by meds, MC = sulfonamides (TMP-SMX), allopurinol, antipsychotics, antisiezure meds
- sxs: no typical target lesions, flat atypical targets, confluent purpuric macules on face and trunk, severe mucosal erosions at one or more sites
- dx: <10% of body surface area
- tx: stop meds immediately and transfer pt to burn center
12
Q
toxic epidermal necrolysis
A
- fever, mucocutaneous lesions, necrosis . and sloughing of epidermis (diffuse, macular rash with indistinct margins and central purpuric region followed by eventual formation of vesicles and bullae as epidermal necrosis develops over days; start on face . and spread inf to trunk and lower extrems), no typical target lesions, flat atypical target lesions, begins with severe mucosal erosions and progresses to diffuse, generalized detachement of epidermis
- dx: >30% of body surface area, nikolsky sign + (sloughing of superficial skin layers with gentle pressure), must have erythema and sloughing of mucosal surfaces including conjunctiva, oral, and vagina (2 or more)
- bx: full-thickness involvement of dermis
- tx: prednisolone
13
Q
pressure or decubitus ulcers
A
- occur over bony prominences (sacrum, ischial tuberosities, trochanters, and heels most often)
- result form necrosis of tissues that becomes ischemic and ulcerates
- MC pathogen: p. aeruginosa, providencia
- sxs: blanchable erythema (first sign), inc temp
- dx: norton scale → lower scores = lower fn, high risk for ulcer; braden scale for predicting pressure sore risk
- tx: reposition q2h, debridement of necrotic tissue, adequate wound cleansing, and application of topical tx
- stage 2: epiderm disrupted w/ subep blisters, crusts, or scaling → may resolve in 2-4wks if tx, avoid wet-to-dry, use semiocclusive (transparent film) or occlusive (hydrocolloids or hydrogels)
- stage 3: full thickness loss of skin into subcut tissue, but not through fascia, eschar formation → debride necrotic tissue, cover with dressings, tx underlying infxn
- stage 4: full thickness loss of skin extending into muscle, bone, jnts, tendons, severe tissue necrosis, osteomyelitis, pathologic fxs, sinus tracts present → same tx as stage 3
14
Q
urticaria
A
- vascular rxn of skin marked by transient appearance of smooth, slightly elevated papules or plaques (wheals) that are erythematous and often itchy, IgE triggers release of histamine from mast cells
- etiology: drugs (NSAID, ASA, opiates, succinylcholine, abx), radiocontrast media\
- sxs: rapid onset pruritic erythematous wheals (lack of ep change, intense itching, presence of advancing edge and receding edge), life-threatening angioedema, features of anaphylaxis (HoTN, resp distress, stridor, GI distress, swallowing difficulty, jnt swelling, pain)
- dx: RAST
- tx: 2nd gen H1 antag: cetirizine, loratadine, fexofenadine (1st line), H2 antag (in combo with 2nd gen H1s - famotidine, ranitidine), 1st gen H1 antac (diphenhydramine, hydroxyzine, chlorpheniramine), epi for laryngeal angioedema
15
Q
necrotizing fasciitis
A
- affects young, healthy patients
- RF: inc age, immunocompromised, chronic illness, ETOHism, IVDU, arises at sites of recent tattoos
- pathogens: GABHS, pathophysiology not fully understood, but bacteria produce enzymes that degrade fascia and allow rapid proliferation of bacteria - local thrombosis, progressive ischemia, liquefaction necrosis, superficial gangrene
- sxs: early (stage 1) - painful at first then swelling, erythema, warmth, tenderness, resembles cellulitis (constitution sxs = high fever, toxicity); (stage 2) - induration worsens, bullae develop; (stage 3) - skin color becomes purple, frank cutaneous gangrene (no longer tender, nonpainful
- dx: XR (subcut air caused by gas-forming orgs within the fascia
- tx: urgent irrigation and debridement, abx (PCN G), adjunct tx (hyperbaric chamber)
