Giant cell tumor of the bladder associated with transitional cell carcinoma.

We report in detail the first giant cell tumor associated with transitional cell carcinoma of the bladder. The giant cell tumor was composed of multinucleated giant and mononuclear stromal cells, and was morphologically indistinguishable from giant cell tumor of the bone. The giant and transitional cell carcinomas showed no evidence of recurrence or metastasis 8 months after transurethral resection. No histogenetic correlation between the cancers was found.