Kaposi sarcoma in association with molluscum contagiosum: an uncommon diagnosis in a single biopsy and potential diagnostic pitfall.

Molluscum contagiosum is a cutaneous poxviral infection that is rarely associated with other skin diseases, such as cutaneous neoplasms. Such associations are likely to be coincidental, except in immunocompromised patients. Kaposi sarcoma, an angioproliferative neoplasm derived from lymphatic endothelium, is mediated by human herpes virus-8 infection and occurs with increased frequency in immunocompromised individuals. We report an unusual case of molluscum contagiosum with underlying cutaneous Kaposi sarcoma diagnosed in a single skin biopsy of a human immunodeficiency virus-positive patient. Our case highlights the importance of adequate sampling to avoid missing secondary diagnoses in histopathologic sections and alerts pathologists and dermatologists to the possibility of coinfection in high-risk patients by 2 virally-mediated skin conditions.