Dermatofibrosarcoma Protuberans: A Tumor With Perineural and Endoneural Cell Features

Seven new cases of dermatofibrosarcoma protuberans were studied. Most tumors were asymptomatic, multinodular, protuberant masses; five were on the trunk or abdomen and two on a thigh. Clinical diagnoses included dermatofibrosarcoma protuberans, dermatofibroma, metastasis, and lymphoma. Histologic examination showed a cartwheel or storiform pattern in each lesion; short fascicles of spindle-shaped tumor cells coursed in various directions and intersected at different angles. Melanocytes were present deep in one lesion. Electron microscopically, the tumor cells showed extensive cytoplasmic processes, moderately dense cytoplasmic matrix, elaborately convoluted nuclei, few profiles of rough-surfaced endoplasmic reticulum and Golgi lamellae, spotty basal laminalike material, and fibrous long-spacing collagen; conspicuously absent were intracellular lysosomes and lipid, and prominent cytoplasmic filamentation. The findings are sufficiently distinctive to be of diagnostic utility and suggest origin from a modified neural supporting cell, such as the endoneural or perineural cell.