Derm Q1

Drug induced urticaria

-2nd most common drug reaction -Starts w/in 36 hrs of taking drug -Aspirin, NSAIDs most common cause -PCN rash, opiates, radiocontrast dye -Can be IgE mediated, complement mediated, immune complex mediated, or caused by drugs that release histamine -Angioedema can occur -Large wheals that appear and resolve within hours, then reappear

Pityriasis Rosea

-Bright red, oval, slightly raised plaques, 2-5 cm, slight scale -Starts as single circular patch (herald patch), develops into lesions that follow lines of cleavage -Christmas Tree distribution -Trunk, arms (rarely on face) -Onset 10-43 y.o. -Seasonal (spring, fall) -Tx: oral antihistamines for itch, topical steroids, UVB light (during 1st week)

Fixed Drug eruption

-Drug eruption that causes solitary lesion, may occasionally cause plaques and bullae -Sharply demarcated, round or oval macule(s) -Red to purplish, fades to brown, varies in size -Appears 30min to 8 hrs after drug -Occurs in same place -Common on back and penis, genital skin is most common site -lesions persist even after drug discontinued

Serum sickness

-Drug eruption, onset 5-21 days after exposure -Urticaria (hives), fever -Severe: arthritis, lymphadenopathy, nephritis, endocarditis -Abx and Immunoglobins (IVIG) most common cause

Erythemia Multiforme

-Lesions start as macules, progress to papules over 48 hrs. -Vesicles form classic target lesions, red-to-violet -Lasts several days -Lesions may be painful or pruritic -Mouth lesions are painful -May have fever, weakness, malaise -Drug reaction: sulfas, PCN, phenytoin, barbiturates, allupurinol -Infection: Herpes simplex, mycoplasma -Most are younger than 20 y.o. -More common in males -Major: due to drug reaction, always w/ mucous membrane involvement -Can be life-threatening (SJS) -All body surfaces can be involved; symmetrical and bilateral -Minor: no mucous membrane involvement

Psoriasis Treatment

-Localized: Topical steroids (clobetasol cream) -Intralesional: Kenalog into plaques -Vitamin D analogs (Dovonex) used to control plaques; 100g per week max to prevent hypercalcemia -Tazarotene -Tar preparations -UVB/PUVA light therapy -Severe cases: oral Methotrexate, Cyclosporin, Soriatane, TNF blockers (Enbral, Stelara, Humira, Remicade)

Exanthematous drug reaction

-Most common drug reaction -Can occur with any drug -Usually <2 weeks after starting drug -Very pruritic (itchy) - pts can't sleep -Macules and/or papules, bright red, coalesces into plaques -Covers large body surface, can involve mouth

Psoriasis

-Salmon-pink papules and plaques with silver-white scale -Scales are loose and when scratched or removed, lesions will bleed -Over-production of epidermal cells stimulates inflammatory reaction in dermis; driven by T-cells -Autoimmune disease -Change in keratinocytes causes shortening of cell cycle resulting in 28x the normal production of epidermal cells, producing plaques -onset: avg 22 y.o. (range 8-55) Dx: skin scrape, biopsy

Treatment of Lichen Planus

-Topical steroids -Intralesional injections of triamcinolone (corticosteroid) -Cyclosporine (immunosuppressant) as mouth wash or systemic (severe cases) -Glucocorticoids -Oral retinoids -PUVA photochemotherapy

Hot tube folliculitis

Cause: Pseudomonas Short incubation 1-5 days Hair follicle infection; clear lesions that clear spontaneously

Ecthyma

Deep type of impetigo that extends into dermis Ulcerative, thick, tender yellow-gray crust Cause: Staph, Strep, Pseudomonas At risk: children, elderly

Furuncle

Deep-seated red nodule with a rim of fine scale that develops a central necrotic plug Common in hairy areas or areas of friction Cause: staph

Staph. epidermidis

Gram-pos bacteria part of normal flora; opportunistic pathogen; forms biofilms Infections associated with intravascular devices (heart valves, shunts, etc.) Can occur in prosthetic joints, catheters, large wounds Septicemia, endocarditis

Where would you look for an enanthem?

In mouth. Rash on mucous membranes

Cellulitis

Infection of deep dermal and subcutaneous layers w/o clear borders Cause: Strep pyogenes, Staph aureus Erythema, edema, warm to touch More generalized redness Onset: days Tx for Purulent infxn: clindamycin, Bactrim, doxycycline, linezolid for 5-10 days Tx for non-purulent infxn: PO cephalexin, clindamycin, dicloxacillin Severe infxn: IV Vanco

Folliculitis

Infection of hair follicle; multiple small, red papules, usually itchy, central pustules Cause: Staph aureus, Pseudomonas aeruginosa Risk: repeated shaving Tx: resolves spontaneously, avoid shaving affected areas, warm compress If persist: mupirocin topical (Bactroban)

Lichen Planus

Inflammatory dermatitis that involves skin and mucous membranes 4P's: Purple, Polygonal (straight sides), Papules, Pruritus (itching) Onset: 30-60 y.o. More common in females; acute or gradual onset increased risk of squamous cell CA

Lines of cleavage

Invisible pattern of skin fibroblasts, best seen in dermatoses such as pityriasis rosea

Carbuncle

Large area of coalescing abscesses or furuncles

Abscess

Localized, wall-off collection of pus (pyoderma), progresses from firm to fluctuant (unstable) Can develop at any cutaneous site Cause: Staph Risk: trauma, DM, obesity, poor hygiene, chronic Staph infection Tx: I&D +/- systemic Abx

Trasnslucent papules, each with a tiny dell or umbilication at center are characteristic of what?

Molluscum contagiosum

Seasonal enterovirus "viral syndromes" in children most often have which skin manifestation?

Morbilliforn exanthem

Sebhorrheic keratosis

Multiple scattered 1 cm brown plaques with velvety surface

Erythrasma

Nonspecific infection of rubbing skin surfaces Cause: Corynebacter minutissimum Common in groin, armpits Brownish color At risk: Diabetic Dx: Wood's lamp (bright red) Tx: topical benzoyl peroxide, mupirocin Systemic tx: doxycycline, macrolides

MRSA

Nosocomial (hospital) and community acquired; prevalence continues to rise Lesions may look purple, often looks like spider bite; lesion fluctuant (unstable) or purulent (pus). Risk: prolonged hospital stay, nursing home residents, DM, HIV, IV drug use, military service Tx: culture; I&D +/- Abx PO meds: Bactrim (TMP/SMX), Septra Tetracyclines (doxy, mino) Clindamycin IV abx: Vanco, Daptomycin, Ceftaroline, Tegecycline

Anaphylaxis

Occurs minutes or hours after administration of drug Most serious drug reaction Antibiotics most common cause

What skin disorder has a "herald patch" that precedes disseminated skin lesions?

Pityriasis rosea

What is most consistent with diagnosis of poison oak dermatitis?

Pruritic localized rash seen 48 hours after exposure

Pulmoplantar Pustulosis

Pustules in various stages, found on hands and feet Eruptions come in waves Females affected more Onset: 50-60 y.o.

Eruptive (guttate) psoriasis

Salmon-pink, tear drop shape papules, not on palms/soles Often preceded by Strep pharyngitis Rash usually appears suddenly

Impetigo

Scabbing eruption with lesions, painful but not itchy Can be bullous (clear or cloudy fluid) or non-bullous (honey-crusted erosions with redness) Cause: Staph aureus, Strep pyogenes At risk: children, elderly Tx: topical Mupirocin ointment (Bactroban), hydrogen peroxide cream Systemic tx: cephalosporins, dicloxacillin

Melasma

Skin pigmentation change mediated by hormones (pregnancy, birth control); not chronic sun exposure More common in darker skinned people

Erysipelas

Soft-tissue infection, more superficial type of cellulitis; Sharp, raised borders with clear demarcation from uninvolved skin Redness (erythema), edema, warm to touch, orange-peel appearance ('peau d'orange); Cause: Strep pyogenes LE and face most affected Acute onset; may have systemic sxs Tx: -PO penicillin or axoxicillin; Can use cephalexin, clindamycin, linezolid if PCN allergy Severe infxn: IV Ceftriaxone or cefazolin Keep skin well moisturized, elevate affected areas

Psoriasis on body folds

Well-demarcated, erythematous, smooth plaque found in skin folds

Pyoderma

any skin infection with formation of pus