Granular Cell Tumor of the Bladder: A Report of Six Cases.

OBJECTIVE: To better characterize granular cell tumor of the bladder, with only 20 cases reported to date and unclear management guidelines.

METHODS: We report five benign and one malignant granular cell tumor of the bladder.

RESULTS: Patients were in the age range of 33 to 73 years. The size of tumor ranged from 0.2 to 6.3 cm. Two benign granular cell tumors were incidental findings with others presenting with painless hematuria. Benign granular cell tumors infiltrated the muscularis propria and were confirmed by immunohistochemistry for S100 protein with negative stains for keratins. The malignant granular cell tumor involved the entire bladder wall with extension into perivesical tissue. Benign granular cell tumors were treated by transurethral resection (TUR) or partial cystectomy; all patients were disease free at last follow-up. The malignant granular cell tumor was treated by anterior exenteration and bilateral pelvic lymphadenectomy. This patient developed pulmonary and pleural metastases 2 years after surgery.

CONCLUSION: Given the locally infiltrative nature of granular cell tumors and that 50% of reported benign granular cell tumors with sufficient follow-up recurred following initial TUR, it is prudent to recommend partial cystectomy if technically feasible. A later TUR at a time of tumor regrowth could result in obstruction of ureters depending on their location and with greater infiltrative growth, with larger subsequent resections be needed for complete removal. In other cases, immediate repeat TUR after a diagnosis of granular cell tumor would lessen the likelihood of local recurrence. Either partial or radical cystectomy is needed for the rare malignant granular cell tumor.