Case report. Granular cell tumors of extremities: comparison of benign and malignant variants.

Granular cell tumors are uncommon soft tissue neoplasms that arise from cells of neural origin. We present three patients with this rare tumor: one with a benign tumor, one with a malignant tumor, and one with a histologically benign tumor that later metastasized to the lung. We studied the difficulty in differentiating between the benign and malignant variants using only histology. We also compared the clinical, radiographic, and pathologic features and the criteria for malignancy, natural history, and prognosis.