A 40 year old woman, originally from sub-Saharan Africa, was referred to dermatology by her general practitioner. She had noticed the appearance of several itchy papules around her mouth five months ago (fig 1⇓). She was otherwise well and had no relevant medical history. She was taking no drugs. ### 1 What is the diagnosis? #### Short answer This cluster of papules in a peri-oral distribution is molluscum contagiosum. #### Long answer The diagnosis is molluscum contagiosum infection. Molluscum lesions are small benign pearly papules caused by the molluscum contagiosum virus (MCV), a poxvirus that infects the skin and mucous membranes. Infection is spread by direct contact and is usually self limiting—most infections last a maximum of six to nine months.1 Molluscum lesions are commonly seen in children (on the face and trunk) and in sexually active young adults (often in the genital area). The infection is more common in warm climates.1 2 After penetrating the skin, MCV infects keratinocytes; an inflammatory response is generated, followed by spontaneous regression. In some people an inflammatory dermatitis develops around the molluscum in the weeks after infection, causing erythema and itching.1 3 Molluscum lesions look like a cluster of papules. The differential diagnoses are broad and include milia, warts, basal cell carcinoma, lichen planus, epidermoid cysts, syringoma, and disseminated cryptococcus infection. Fig 2 Histology of molluscum contagiosum. C=central crater; D=dermis; E=epidermis; K=keratin …