Malignant granular cell tumor.

A malignant granular cell tumor (MGCT) appeared on the subungual tissue of the right index finger of a 51-year-old woman. Two years after resection of the tumor, it recurred, and the finger finally had to be amputated. Six months later, she noticed multiple cutaneous nodules on her trunk. Despite chemotherapy and X-ray irradiation, the patient died 18 months after the second operation. Histology of the specimen revealed a proliferation of both polygonal and spindle-shaped cells with large hyperchromatic nuclei and an eosinophilic granular cytoplasm. Peripheral nerves were encompassed by the tumor cells. Immunohistochemically, the tumor cells were positive for S-100 protein and Leu 7 (myelin-associated glycoprotein). These findings support the hypothesis that MGCT cells are of Schwann cell origin.