Study guide
High-Yield Dermatology for the PANCE
Dermatology accounts for roughly 5% of the NCCPA PANCE blueprint, emphasizing pattern recognition of common infections, inflammatory conditions, and skin cancers. This guide targets the highest-frequency, board-testable diagnoses and their first-line management, updated to current (2024-2026) guidelines.
Skin Cancers & Precancers
- ◆Basal cell carcinoma (most common skin cancer): pearly, telangiectatic papule with rolled borders +/- central ulceration on sun-exposed skin; rarely metastasizes; treat with excision or Mohs (face/high-risk sites).
- ◆Squamous cell carcinoma: firm hyperkeratotic/ulcerated nodule; higher metastatic risk than BCC, especially on lip/ear; arises from actinic keratosis (rough, scaly, sandpaper macules — precancer).
- ◆Melanoma ABCDEs: Asymmetry, Border irregular, Color variegation, Diameter >6 mm, Evolving. Breslow depth is the single most important prognostic factor. Narrow-margin (1-3 mm) excisional biopsy through the full thickness is preferred; avoid a superficial shave that transects the lesion and compromises depth staging (NCCN does allow saucerization/deep-shave that captures the full base).
- ◆Actinic keratosis management: cryotherapy for isolated lesions; topical 5-FU, imiquimod, or field therapy for diffuse disease.
- ◆Risk factors across all: UV exposure, fair skin (Fitzpatrick I-II), immunosuppression; the ugly-duckling sign flags melanoma.
Bacterial & Superficial Infections
- ◆Impetigo: honey-colored crust (nonbullous, S. aureus/GAS) or flaccid bullae (bullous, S. aureus exfoliative toxin); topical mupirocin for limited disease, oral cephalexin if widespread.
- ◆Cellulitis (non-purulent): usually beta-hemolytic strep/MSSA; treat with cephalexin (500 mg PO TID-QID) or dicloxacillin — MRSA coverage is generally NOT needed and a 5-6 day course suffices if improving. Purulent (abscess): I&D is primary; cover MRSA with TMP-SMX or doxycycline.
- ◆Erysipelas: sharply demarcated, raised, bright-red plaque (usually GAS) with fever — more superficial/well-defined than cellulitis.
- ◆Necrotizing fasciitis red flags: pain out of proportion, rapid progression, crepitus, bullae, systemic toxicity — surgical emergency requiring debridement + broad-spectrum abx (e.g., vancomycin + piperacillin-tazobactam + clindamycin).
- ◆Staph scalded skin syndrome (young children): diffuse erythema + positive Nikolsky, spares mucosa (contrast with SJS/TEN which involves mucosa).
Fungal, Viral & Infestations
- ◆Dermatophytes (tinea): scaly annular plaque with central clearing; KOH shows septate hyphae. Topical azoles/terbinafine, but tinea capitis and onychomycosis need ORAL terbinafine/griseofulvin.
- ◆Tinea versicolor: hypo/hyperpigmented macules on trunk, KOH spaghetti-and-meatballs; treat topical selenium sulfide/ketoconazole.
- ◆Herpes zoster: painful dermatomal vesicles; antivirals (valacyclovir) ideally within 72 hrs. Hutchinson sign (nasal tip) = risk of ophthalmic involvement — urgent ophthalmology.
- ◆Molluscum contagiosum: umbilicated flesh-colored papules (poxvirus); self-limited in kids so observation is reasonable — FDA-approved options now exist (in-office cantharidin/Ycanth 2023; at-home berdazimer/Zelsuvmi gel 2024). Consider HIV if extensive in adults.
- ◆Scabies: intensely pruritic (worse at night) burrows in web spaces/wrists/genitals; first-line permethrin 5%, treat close contacts and wash linens; oral ivermectin for crusted/refractory disease.
Papulosquamous & Inflammatory Disorders
- ◆Psoriasis: well-demarcated salmon plaques with silvery scale on extensor surfaces/scalp; Auspitz sign (pinpoint bleeding), nail pitting. First-line topical steroids +/- vitamin D analogs; biologics (TNF/IL-17/IL-23) for moderate-severe.
- ◆Atopic dermatitis: pruritic, ill-defined eczematous patches in flexural areas; part of atopic triad. Emollients + topical steroids; topical calcineurin inhibitors (or crisaborole/topical JAK) for face/folds.
- ◆Lichen planus: 6 P's — pruritic, purple, polygonal, planar papules/plaques with Wickham striae; oral involvement (lacy white); check hepatitis C.
- ◆Pityriasis rosea: herald patch followed by christmas-tree distribution on trunk; self-limited; consider RPR to exclude secondary syphilis.
- ◆Seborrheic dermatitis: greasy yellow scale on scalp/nasolabial folds; topical antifungal (ketoconazole) + low-potency steroid; dandruff in infants = cradle cap.
Acne, Rosacea & Hypersensitivity
- ◆Acne ladder (2024 AAD): comedonal - topical retinoid; inflammatory - add benzoyl peroxide +/- topical antibiotic (fixed-dose combinations strongly preferred, never antibiotic monotherapy); moderate - oral doxycycline; consider topical clascoterone (anti-androgen) as an adjunct; severe/nodulocystic - isotretinoin (requires iPLEDGE, pregnancy testing for those who can conceive, teratogenic).
- ◆Rosacea: central facial erythema, telangiectasias, papulopustules, flushing triggers; NO comedones. Topical metronidazole/ivermectin; oral doxycycline; brimonidine for erythema.
- ◆Urticaria: transient wheals <24 hrs, second-generation H1 antihistamines first-line (may up-dose to 4x); angioedema without urticaria consider ACE-inhibitor or hereditary (C1-inhibitor) cause.
- ◆Erythema multiforme: target lesions, often HSV-triggered; distinct from SJS/TEN (drug-induced, mucosal, epidermal detachment).
- ◆Contact dermatitis: linear/geometric vesicular eruption (poison ivy = Type IV delayed hypersensitivity); remove allergen, topical/oral steroids.
Life-Threatening & High-Yield Emergencies
- ◆SJS/TEN: drug-triggered (sulfa, anticonvulsants, allopurinol, NSAIDs); painful mucocutaneous erosions, positive Nikolsky. <10% BSA = SJS, >30% = TEN; stop drug, ICU/burn unit supportive care.
- ◆DRESS syndrome: fever, morbilliform rash, facial edema, eosinophilia, LFT elevation, 2-8 weeks after drug (anticonvulsants, allopurinol); stop drug, systemic steroids.
- ◆Pemphigus vulgaris: flaccid bullae, positive Nikolsky, painful oral erosions, IgG anti-desmoglein; systemic steroids/rituximab. Contrast bullous pemphigoid: tense bullae, negative Nikolsky, elderly, pruritic.
- ◆Melanoma/aggressive lesions: any rapidly changing or bleeding pigmented lesion warrants excisional biopsy and prompt referral.
- ◆Erythroderma (>90% BSA erythema): risk of hypothermia, high-output failure, infection — identify trigger (psoriasis, drug, cutaneous lymphoma) and admit.