Focal palisading granuloma in the prostate and bladder. A clinicopathologic study of 88 total cystectomy specimens

In close inspection of 88 total cystectomy specimens, 20 were found to have rheumatoid nodule-like lesions known as "focal palisading granulomas". Nineteen of these nodules were from patients with a history of previous transurethral resection (TUR). Such granulomas were identified in the prostate in 3, in the bladder in 13, and in both prostate and bladder in another 3. The remaining one patient had undergone a cold cup biopsy followed by electric coagulation. The granulomas were characterized microscopically by the presence of central necrosis surrounded by palisading histiocytes and fibroblasts, and were situated in areas of the previous TUR. There were no granulomas in 20 other patients with no history of previous TUR and other surgical procedures. The lesions were commonly seen in the superficial zone of the bladder wall and in the prostate and, as proved by serial sections, opened onto the mucosal surface of the bladder and urethra, respectively. The observation confirmed that the focal palisading granulomas occurred not only in the prostate but also in the bladder, and seemed to be closely related to surgical procedures, especially to the electrocauterizing process, in both the bladder and prostate.