Dirty-appearing ­truncal eruption

Over the course of several months, an otherwise healthy 17-year-old woman developed an asymptomatic and progressively worsening rash over her torso. Topical emollients and antifungal creams provided no improvement in her condition.

Physical examination revealed hyperpigmented, thin papules with a faintly verrucous surface coalescing into reticulate plaques over the woman's central and inframammary chest, flanks, and back. KOH preparation of ...