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Molluscum contagiosum

Molluscum contagiosum virus (a poxvirus)

Overview

A common pox-viral skin infection causing small umbilicated papules. In children it is widespread and innocent; acquired sexually in adults it clusters in the genital/pubic area. Self-limiting in the immunocompetent; extensive/atypical lesions raise the question of HIV.

Recognise

Small (1–5 mm), firm, pearly, dome-shaped papules with central UMBILICATION
Often clustered on the lower abdomen, genitals and inner thighs in adults
Usually asymptomatic; may become inflamed as they resolve

Red flags

Extensive/giant or facial lesions in an adult → consider HIV/immunosuppression

Differentials & how to tell them apart

Anogenital warts (HPV)verrucous/filiform, NOT umbilicated

Herpes simplex viruspainful vesicles/ulcers, not pearly umbilicated papules

Condylomata lata (secondary syphilis)flat, moist, serology positive

Investigations

Clinical (umbilicated papules). Consider an HIV test if genital/extensive in an adult; biopsy only if atypical.

Management

Reassurance — self-limiting; treat genital lesions as part of an STI screen

1Reassure: it resolves spontaneously over months in the immunocompetent; avoid squeezing/shaving over lesions (autoinoculation).Gate: Extensive or atypical lesions in an adult → test for HIV/immunosuppression
2Genital lesions: STI screen; optional cryotherapy/topical treatment; avoid contact with lesions.

Usually none (self-limiting) — reassurance; resolves over months

Cryotherapy / topical agents — optional for genital or cosmetically troublesome lesions

Key points

Central umbilication is the giveaway and separates it from warts. Florid molluscum in an adult is an HIV indicator condition.

Monitor & prognosis

Resolution over months; HIV test where indicated.

Self-limiting in the immunocompetent.

Source: NICE CKS Molluscum contagiosum; BASHH