Primary osteosarcoma of the ureter.

Primary osteosarcoma of the ureter is an extremely rare disease. Herein, the authors report a case of extraosseous osteosarcoma arising in the ureter of a 64-year-old woman. Ureteroscopy showed a papillary mass that protruded into and almost completely occluded the lumen. The tumor was successfully removed, and pathologic analysis identified mitotically active spindle cells and focal areas that contained osteoid. The tumor cells were strongly positive for vimentin but negative for cytokeratin (CK), CK7, CK20 and leukocyte-common antigen, supporting a diagnosis of high-grade extraosseous osteosarcoma of the ureter. The patient recovered well from surgery and exhibited no evidence of local recurrence or distant metastasis 6 months after the surgery. To the best of our knowledge, this is only the third reported case of primary osteosarcoma of the ureter.