Malignant Granular Cell Tumor of Soft Tissues: A Study of Two New Cases

We describe 2 cases of malignant granular cell tumor. A marked discrepancy exists concerning the criteria of malignancy of this rare entity, which was diagnosed in male patients aged 41 and 52 years, respectively. They presented with tumors measuring more then 3.5 cm; one arose in the dermis and subcutaneous tissue in the region of the scapula, whereas the other was situated in deeper soft tissue in the pelvis. One case, with previous diagnosis of benign granular cell tumor, presented local recurrence 2 years after the initial diagnosis. The other case presented a fascicular pattern of growth invading adjacent muscular tissue. Both neoplasms were composed of polygonal and spindle cells, showing abundant cytoplasm, vesicular nuclei with large nucleoli, high nuclear-to-cytoplasmic ratio, and polymorphism. Immunohistochemically, the neoplastic cells of both cases were positive for vimentin, S 100 protein, neuron-specific enclose (NSE), and CD68. In addition, high expression of p53 and MiB 1 (Ki67) was detected. Herein, we discuss the morphologic and immunohistochemical criteria of malignancy of granular cell tumors.