Incidence and pathology of spontaneous renal pelvis transitional cell carcinomas in rats.

Spontaneous transitional cell carcinoma (TCC) originating from renal pelvis is very rare. Metastasis from this tumor having been reported only once previously. Data from control groups of 17 carcinogenicity studies in Sprague-Dawley and 10 carcinogenicity studies in Fischer 344 (F-344) rats were reviewed and evaluated to determine the incidence and pathology of TCC. Renal pelvis TCC were observed in 1 male and 1 female Sprague-Dawley rat and in 1 male F-344 rat. Metastasis from TCC to the lung was observed in 1 male Sprague-Dawley rat. Detailed histopathological features of this tumor are described and discussed.