A 24-year-old woman presented for treatment of multiple skin lesions that appeared approximately 10 years previously. These began rather suddenly as asymptomatic "pimples" in the groin and axillary regions that erupted in crops over several years and remained unchanged. Over the previous few years, the lesions had increased in number and distribution. The patient was disturbed by their appearance. Her family history was remarkable for a sister with similar lesions, although not as extensive. The sister was not available for evaluation.Examination showed numerous discrete, darkbrown, flat-topped, smooth, 1-to 4-mm papules over the medial upper arms, lateral breasts, medial thighs, lower abdomen, and buttocks (Figs 1 through 3). The face, neck, axillary vault, and intertriginous aspects of the groin were spared.A biopsy specimen of a typical lesion is shown in Fig 4. What is your diagnosis? Figure 2.Figure 4. Downloaded From: http://archderm.jamanetwork.com/ by a Karolinska Institutet University Library User on 05/31/2015