Rippled-pattern sebaceoma: a report of a lesion on the back with a review of the literature.

A 68-year-old Japanese man presented with a nodule that had been present for 5 to 6 years on the right side of the back. Physical examination revealed a dome-shaped, 12 x 13-mm, dark red nodule. It was excised with a 2 to 3-mm margin. The patient remained free of disease during 77 months of follow-up. Microscopic examination revealed a bulb-like tumor in the dermis, contiguous with the overlying epidermis. It was composed of small, monomorphous, cigar-shaped basaloid cells in linear, parallel rows, resembling the palisading of nuclei of Verocay bodies, and presenting a rippled-pattern. There were scattered cells showing sebaceous differentiation with vacuolated cytoplasm and scalloped nuclei. There were tiny, duct-like spaces. The tumor revealed characteristics of rippled-pattern sebaceoma. The present case is the first reported rippled-pattern sebaceous neoplasm on the back. Many spindle cell tumors, such as basal cell carcinoma, pleomorphic adenoma, dermatofibrosarcoma protuberans, myofibroblastoma, and leiomyoblastoma, in addition to trichoblastoma and sebaceoma, can have a rippled-pattern.