A case of combined nevus: compound nevus and spindle cell Spitz nevus.

Combined nevi consisting of a Spitz nevus and an acquired nevus are unusual, and, to our knowledge, the combination of a spindle cell Spitz nevus and an overlying compound nevus has not been previously reported. We report a 17-year-old girl with a nodule on the left anterior lower extremity. The nodule was asymptomatic, firm, brown, symmetrical, dome-shaped, 8 mm in diameter, and not found with ulceration. Histological findings showed proliferation of spindle-shaped cells with an overlying compound nevus. The spindle-shaped cells were large, non-pigmented, uniform in size and shape, with rare mitoses and without nuclear atypia, and arranged in a storiform pattern in thick collagen bundles. They stained positively for S-100 and negatively for HMB-45. The lesion was considered to be a new type of combined nevus consisting of a spindle cell Spitz nevus and an overlying compound nevus.