Abstract

Radiation-induced epithelial proliferation in the urinary bladder mimicking urothelial carcinoma has received only a little attention in the literature. Herein, we describe two cases of radiation-induced epithelial proliferative changes, which mimicked invasive urothelial carcinoma. Cystoscopy revealed bullous or edematous mucosal changes with multiple hemorrhagic foci. Microscopically, we observed inverted epithelial proliferation, forming nests and cords extending into the lamina propria. The epithelial cells in these nests and cords exhibited enlarged, hyperchromatic and pleomorphic nuclei, closely mimicking the infiltrative growth of urothelial carcinoma. However, the presence of radiation-induced changes was validated by the observation of abundant vacuolated cytoplasm, normal or slightly increased nuclear to cytoplasmic ratios, the absence of mitotic activity, dilated blood vessels containing frequent fibrin thrombi, scattered atypical fibroblasts, and the patients' previous history of radiation treatment. Radiation-induced changes should be always included in differential diagnoses of proliferative epithelial lesions in the urinary bladder and a pertinent clinical history of radiotherapy should be searched.

• Keywords: Cystitis;Radiation Injuries;Urinary Bladder;