A 35-year-old man has noted a small bump on his upper trunk for the past 6 weeks. On physical examination, there is a solitary, 0.4-cm, flesh-colored nodule on the upper trunk. The dome-shaped lesion is umbilicated, and a curd-like material can be expressed from the center. This material is smeared on a slide, and the Giemsa stain shows many pink, homogeneous, cytoplasmic inclusions. The lesion regresses over the next 2 months. Which of the following infectious agents most likely produced this lesion?

The pink cytoplasmic inclusions, called molluscum bodies, are characteristic of this lesion. Immunocompromised individuals may have multiple, larger lesions. The infectious agent is a poxvirus. Disseminated fungal infections such as histoplasmosis involving skin are uncommon except in immunocompromised patients. Human papillomavirus (not a toad) is implicated in the appearance of verruca vulgaris or the common wart. Staphylococcus aureus is implicated in the formation of the lesions of impetigo and pustular skin infections. There are a variety of superficial fungal infections caused by dermatophytes, such as Tinea corporis producing a scaling plaque. Varicella-zoster virus causes shingles, characterized by a dermatomal distribution of clear, painful vesicles.