Granular cell tumor of the urinary bladder with pseudoepitheliomatous hyperplasia and colocalization with adenocarcinoma.

Granular cell tumor of the bladder is exceptionally rare, with only 11 cases reported in the published reports. Pseudoepitheliomatous hyperplasia of the overlying squamous epithelium has been observed in non-bladder granular cell tumors. We herein report the first case of bladder granular cell tumor to exhibit pseudoepitheliomatous hyperplasia. This phenomenon is significant as it may potentially lead to difficulty in the distinction between infiltrative squamous cell carcinoma and pseudoepitheliomatous hyperplasia in cases of granular cell tumor of the bladder. This case also represents the first granular cell tumor to demonstrate colocalization with adenocarcinoma of the bladder. Based on our findings and a review of the published reports, management for granular cell tumor of the bladder should involve a course of local resection combined with active surveillance given its typical benign course, albeit with the potential for local recurrence.