Malignant granular cell tumors: report of a case and review of the literature.

Background: Granular cell tumors are uncommon soft tissue tumors and are more commonly benign. Malignant granular cell tumors are extremely rare, may be confused with other soft tissue sarcomas, and can be diagnosed only when metastatic disease that has the same histologic features as the primary tumor has been identified. Metastases are more commonly seen in lymph nodes and lungs; however, often the metastatic disease is not identified at the time of initial diagnosis and presents anywhere from 3 to 37 months after initial treatment. Certain findings, such as histologic appearance and size, may suggest that a granular cell tumor has uncertain malignant potential.

Methods: We evaluated a patient with a granular cell tumor of uncertain malignant potential of the left chest wall and no evidence of metastatic disease on physical examination with a preoperative work-up to identify sites of occult disease.

Results: The patient was found to have suspicious ipsilateral axillary adenopathy on magnetic resonance imaging and computed tomography scan. No other regional or distant disease was identified. The patient underwent an en bloc wide excision and axillary lymph node dissection. Metastatic disease was identified in nine of 23 lymph nodes.

Conclusions: Patients who are diagnosed with a granular cell tumor of uncertain malignant potential may benefit from preoperative radiologic evaluation because occult metastatic disease may be identified, alter the surgical approach, and possibly affect the long-term outcome.