[A case of sarcomatoid carcinoma of the urinary bladder].

We reported a case of sarcomatoid carcinoma of the bladder in a 62-year-old man admitted to our hospital because of intermittent macroscopic hematuria. Under the diagnosis of invasive bladder tumor, the patient underwent radical cystectomy and construction of an ileal conduit. Microscopic examination showed a tumor composed of spindle cells that are arranged in a storiform pattern reminiscent of that seen in malignant fibrous histiocytoma without any component of obvious epithelial tumors. Immunohistochemical examination showed that the spindle cells were positive for cytokeratin and we diagnosed the tumor as sarcomatoid carcinoma. The patient has remained well without any evidence of recurrence for 30 months after radical cystectomy. The distinction between sarcomatoid carcinoma that lacks conventional epithelial component and MFH is very difficult and important.