Malignant granular cell tumor. Report of a case with DNA ploidy analysis.

Malignant granular cell tumor is a rare neoplasm that has been reported to occur at various sites. Although there are no reliable histologic criteria to differentiate the benign from the malignant form of granular cell tumor, in many reported cases cellular pleomorphism and the presence of mitotic activity suggested an aggressive nature. We report a case of malignant granular cell tumor that involved the subcutaneous tissue in the sacrococcygeal area. The tumor showed cellular atypia on histologic sections, but mitotic figures were rare. The tumor recurred and produced widespread metastasis, resulting in the death of the patient. DNA flow cytometry demonstrated DNA diploidy, suggesting that such analysis may not be beneficial in predicting the behavior of these tumors.