A 71-year-old Puerto Rican woman with a history of breast cancer was referred for dermatologic evaluation by her oncologist for reevaluation of pigmented lesions on the scalp, initially noted 8 years earlier. She had no personal or family history of melanoma. Physical examination revealed a 6-mm blue papule with 16 discreet 2- to 3-mm blue satellite macules within a normally pigmented 2-cm area of the left parietal scalp (Figure 1, shown after biopsy). Biopsy specimens of the largest papule (Figure 2 and Figure 3, hematoxylin-eosin, original magnification ×40 and ×200, respectively) and a satellite papule were taken.