Primary osteosarcoma of the bladder: a case report and review of the literature.

Primary osteosarcoma of the bladder is an extremely rare neoplasm. Fewer than 30 cases have been reported in the world's literature, some of which may not meet the strict modern criteria for inclusion in this group. The authors report a case of such a neoplasm occurring in an 86-year-old man and review the clinical presentation, histopathology and clinical course of this unusual tumor.