A histopathologic study of twenty urinary bladder neoplasms in the cat

Urinary bladder neoplasms were diagnosed in 20 cats during an eight-year period. Histologic types included angioma, intravenous leiomyoma, adenocarcinoma, squamous cell carcinoma, transitional cell carcinoma, leiomyosarcoma, haemangiosarcoma, lymphoma, and embryonal rhabdomyosarcoma. Malignant neoplasms (18/20; 90 per cent) and malignant epithelial neoplasms (12/20; 60 per cent) predominated. Adenocarcinomas and squamous cell carcinomas were almost as common as transitional cell carcinomas. All adenocarcinomas and most transitional cell carcinomas were exophytic, in contrast to all squamous cell carcinomas and most sarcomas which were endophytic. Metaplastic, hyperplastic, and in situ changes in the adjoining mucosa of the bladder were seen commonly in the cases of epithelial neoplasms; Brunn's nests were associated more with the adenocarcinomas than with the other epithelial tumours.