Diagnosis: Molluscum contagiosum
Mollusca contagiosa on a girl's thigh.. Clinical photograph sourced from Wikimedia Commons (CC BY-SA 4.0). Attribution: Gzzz.
Discrete, dome-shaped, flesh-colored to pearly papules with central umbilication (dell). Usually 2-5mm. Distribution: trunk, extremities, face in children; genital area in adults. May develop surrounding eczematous dermatitis (molluscum dermatitis). Extensive in HIV/immunosuppression.
Self-limited in immunocompetent (6-12 months average, may take 2-4 years). Spread by skin contact, swimming, shared towels. Giant molluscum (>1cm) or extensive disease suggests immunodeficiency — check HIV status in adults.
Often self-resolving — watchful waiting is appropriate. Destructive: cryotherapy, curettage, cantharidin. Topical: imiquimod (off-label), tretinoin, podophyllotoxin. Extensive/HIV: treat underlying immunodeficiency, cidofovir for refractory cases.
Verruca, Folliculitis, Milia, Basal cell carcinoma (solitary), Cryptococcosis (in HIV), Histoplasmosis (in HIV)
Central umbilication is the key diagnostic feature. DOIA (dermatitis of immunocompromise with atypical features) — extensive molluscum in adults warrants HIV testing. Cantharidin is effective but must be applied carefully to avoid blistering.
Tags: molluscum, viral, poxvirus, pediatric, sexually transmitted