Osteosarcoma of the urinary bladder. Report of a case and review of the literature.

A 65-year-old man with hematuria had a large polypoid tumor of the urinary bladder which on microscopic examination was an osteosarcoma, only the 22nd example reported in this organ. The tumor was initially misinterpreted as a transitional cell carcinoma because of an absence of osteoid in the initial slide prepared from a biopsy of the neoplasm. Most of the patients with osteosarcoma of the bladder have been male; they have ranged from 41 to 83 (average 62) years of age. The tumors have characteristically been large and polypoid and have most commonly been located in the trigone. Follow-up is available for 21 patients; 18 of them died within 6 months or less. Three patients were still alive 14 months, 18 months, and 2 years postoperatively. Osteosarcoma of the bladder should be distinguished from other bladder tumors that may be associated with bone formation such as carcinosarcomas and transitional cell carcinomas with osseous metaplasia of their stroma, both of which have a better prognosis than osteosarcoma.