Intramuscular granular cell tumor in the lower extremities.

UNLABELLED: Granular cell tumors are uncommon but typically histologically benign neoplasms that occasionally behave as malignant tumors. Differentiation of benign granular cell tumors from malignant counterparts with radiographic and/or histologic analysis is crucial for physicians. We retrospectively studied five cases of intramuscular granular cell tumors arising in the lower extremities. All tumors had been histologically diagnosed as benign and were resected with a wide surgical margin. The minimum followup was 1 year (mean, 45 months; range, 12-119 months) after surgery. Four patients had no local recurrence or distant metastasis (at a minimum of 18 months followup), whereas one patient with lymph node metastasis had a recurrence and distant metastasis 3 months after surgery resulting in death. Intramuscular granular cell tumors can be diagnosed based on their characteristic MRI features, such as peripheral high intensity on T2-weighed images, and histologic evaluation. The histologic criteria described by Fanburg-Smith et al. can differentiate malignant granular cell tumors from benign tumors. A wide resection seems suitable for most granular cell tumors in the extremities. LEVEL OF EVIDENCE: Level IV, diagnostic study. See the Guidelines for Authors for a complete description of evidence.