Iatrogenic granulomas of the prostate and the urinary bladder.

In 1059 patients who had transurethral resections (TUR) of the prostate 8 cases (0.8%) with nonspecific granulomas were found. In another group of 280 patients treated by TUR for tumours of the urinary bladder 5 cases (1.8%) had granulomatous lesions in the resectates. The granulomas were observed only in patients with prior surgical trauma of the prostate and the bladder with an incidence of 14% and 6.5%, respectively. None of the patients had systemic diseases. Morphologically, two types of granulomas were observed, foreign-body-type and necrotizing. Carbonization rests were frequently noticed in the granulomatous lesions and the configurations and anatomical distribution of the granulomas suggest a common pathogenesis by electrocauterization. Immunohistochemically, histiocytic cells were stained by antibodies against lysozyme. In the prostate, no reaction by antibodies against prostate specific antigen was observed in the granulomas. The findings are compared to previously reported cases of iatrogenic granulomas in the prostate, the urinary bladder and other organs. It is concluded that the granulomas arise as a local reaction to previous surgery, maybe involving hypersensitivity to locally altered collagen.