ABPS Dermatology (BCD) cheat sheet

SJS/TEN: epidermal detachment <10% = SJS, 10–30% = overlap, >30% = TEN; culprit drug withdrawal and supportive care are central.

Anaphylaxis: IM epinephrine 0.01 mg/kg (max 0.5 mg) to the anterolateral thigh; repeat every 5–15 minutes; antihistamines and steroids are adjuncts.

Chronic urticaria: recurrent wheals or angioedema >6 weeks; second-generation H1 antihistamines are first-line; omalizumab is used for refractory disease.

Psoriasis: well-demarcated plaques with silvery scale; Koebner phenomenon occurs at trauma sites; topical steroids or vitamin D analogues treat limited disease; biologics treat moderate-severe disease.

Atopic dermatitis: pruritic eczematous lesions; barrier repair and topical corticosteroids or calcineurin inhibitors are mainstays; dupilumab is used for moderate-severe disease.

Allergic contact dermatitis: type IV delayed hypersensitivity; patch testing identifies the allergen; irritant contact dermatitis is more common and non-immune.

DRESS: rash, facial edema, fever, eosinophilia, lymphadenopathy, and organ involvement; stop the culprit drug; HHV-6 reactivation may occur.

Cellulitis: nonpurulent cellulitis is usually streptococcal or staphylococcal; purulent cellulitis or abscess requires drainage; rapid spread or systemic toxicity needs urgent care.

Melanoma ABCDE: Asymmetry, Border irregularity, Color variation, Diameter >6 mm, Evolving; not all melanomas follow these criteria.

Pemphigus vulgaris: suprabasal acantholysis with tombstoning; DIF shows intercellular IgG in a chicken-wire pattern; anti-desmoglein 3 and 1 correlate.

Bullous pemphigoid: subepidermal blister with eosinophils; DIF shows linear IgG and C3 at the basement membrane zone; anti-BP180 and anti-BP230 are relevant.

Lichen planus: wedge-shaped hyperkeratosis, saw-tooth rete ridges, band-like lymphocytic infiltrate, and Civatte bodies.

Psoriasis: parakeratosis, Munro microabscesses, regular acanthosis, thinned suprapapillary plates, and dilated vessels.

Basal cell carcinoma: basaloid nests, peripheral palisading, stromal retraction clefts, and mucin; nodular subtype is most common.

Squamous cell carcinoma: atypical keratinocytes with intercellular bridges and keratin pearls; assess depth, perineural invasion, and margins.

Melanoma: Breslow depth is measured from the granular layer or ulcer base to the deepest invasive cell; mitoses and ulceration affect prognosis.

Dermatofibroma: spindle-cell proliferation with collagen trapping and overlying epidermal induction; the dimple sign is characteristic.

Seborrheic keratosis: horn pseudocysts and basaloid cells; benign lesion without significant atypia.

Mohs surgery examines 100% of peripheral and deep margins layer by layer; it is indicated for high-risk BCC/SCC and tissue-sparing sites.

Melanoma margins: in situ 0.5–1 cm; ≤1 mm depth 1 cm; 1–2 mm depth 1–2 cm; >2 mm depth 2 cm.

Fusiform excision: length-to-width ratio about 3:1 with 30-degree tips reduces dog-ears; undermine as needed for closure.

Lidocaine maximum: 4.5 mg/kg without epinephrine; 7 mg/kg with epinephrine; bupivacaine maximum about 3 mg/kg.

Suture removal: face 5–7 days, scalp 7–10 days, trunk or extremities 10–14 days; lower leg wounds often need longer.

Full-thickness skin grafts need a vascularized recipient bed and provide better contour; split-thickness grafts cover larger areas with more contraction.

Anticoagulants are generally continued for cutaneous surgery; check INR for warfarin; direct oral anticoagulant timing depends on bleeding risk.

Surgical site infection signs: increasing pain, erythema, warmth, drainage, and fever; Staphylococcus aureus is common.

Flap reconstruction uses adjacent tissue with its own blood supply; graft survival depends on recipient bed vascularity.

Infantile hemangioma: proliferation in early months followed by involution; oral propranolol treats problematic lesions; topical timolol treats superficial lesions.

Port-wine stain: capillary malformation present at birth; pulsed dye laser is first-line; segmental V1 facial stain warrants Sturge-Weber evaluation.

Tinea capitis: oral griseofulvin or terbinafine is required; topical therapy alone is inadequate; scaling, alopecia, and lymphadenopathy are common.

Kawasaki disease: fever ≥5 days plus 4 of 5 features; IVIG plus aspirin reduces coronary artery risk.

Diaper dermatitis: irritant type is most common; Candida shows beefy-red plaques with satellite pustules; topical nystatin or azole treats Candida.

Hand-foot-mouth disease: coxsackievirus A16 or enterovirus 71; oral vesicles and acral papulovesicles; treatment is supportive.

Atopic dermatitis in infants: face and extensor involvement; flexural involvement occurs later; topical steroids and emollients are mainstays.

Measles: Koplik spots and cephalocaudal maculopapular rash; airborne isolation; vitamin A is used in severe cases.

Botulinum toxin: blocks presynaptic acetylcholine release; onset 2–7 days; duration 3–6 months; avoid in neuromuscular junction disorders.

Hyaluronic acid filler: reversible with hyaluronidase; urgent use is required for vascular occlusion or vision loss.

Filler vascular occlusion: blanching, pain, dusky skin, or vision loss; stop injection and use hyaluronidase urgently for hyaluronic acid filler.

Chemical peels: superficial peels use alpha-hydroxy acids or low-strength trichloroacetic acid; medium peels use higher trichloroacetic acid; deep peels use phenol.

Laser hair removal: targets follicular melanin; dark terminal hair on light skin responds best; Nd:YAG is safer in darker skin.

Photodynamic therapy: photosensitizer plus light treats actinic keratoses and some superficial nonmelanoma skin cancers; photosensitivity follows treatment.

Dynamic rhytides appear with muscle contraction and respond to botulinum toxin; static rhytides persist at rest and often need fillers or resurfacing.

Sunscreen: broad-spectrum SPF protects against UVB and UVA; reapply every 2 hours and after swimming or sweating.