[Unusual development of urothelioma of the upper urinary tract].

A case of extrarenal spreading of transitional cell carcinoma caused by rupture of ureterohydronephrosis by ureteral transitional cell carcinoma is reported. Ultrasonography and CT revealed the presence of a severe right ureterohydronephrosis with large septa and a 2 cm diameter exophytic neoplasia of the middle ureter. Nephroureterectomy was performed with excision of a perirenal mass. Histologic examination revealed the presence of transitional cell carcinoma in the perirenal mass, caused by dissemination after renal rupture. CT and ultrasonography were not able to differentiate hydronephrosis from pericapsular spreading because of the extreme disruption of the renal parenchyma.