Molluscum contagiosum is a virus that causes characteristic pearly lesions on the surface of the skin. Small clusters of mollusca are a nuisance rather than a serious health problem. However, the mollusca can be more widespread and disfiguring in people with impaired cell-mediated immunity. Molluscum contagiosum virus is common in children. In adults it can also be contracted during sexual activity and might indicate a need for diagnostic testing for other, more serious sexually transmitted infections in young, sexually active adults.