Malignant granular cell tumor. A clinico-pathologic and ultrastructural study of a case.

The clinical and light- and electron-microscopic features of a malignant granular cell tumor in a 64-year-old man are reported. The ultrastructural appearance, with abundance of cytoplasmic "phagosomes", may help in the differential diagnosis. The light-microscopic findings and some ultrastructural observations support the suggestion that the tumor originated from peripheral nerves, and that a close relationship exists between malignant granular cell tumors and malignant Schwannoma.