[Urothelial carcinoma of ureter with neuroendocrine differentiation: a case report].

A 73-year-old woman complained of gross hematuria. Urine cytology showed small cell carcinoma (SmCC) cells mixed with urothelial carcinoma (UC) cells. Cystoscopy revealed a bladder tumor around the right ureteral orifice. Abdominal CT demonstrated severe right hydronephrosis. Pelvic MRI showed a mass (approximately phi5 cm) in the urinary bladder wall that protruded into the lumen. TUR biopsy of the bladder tumor was SmCC. With laparoscopic nephrectomy/open ureterectomy, distal end (approximately 10 cm) of the right ureter was tumorous and obstructed. The tumor invaded into the urinary bladder/peritoneum and was unresectable. The tumor of lower-end of ureter tumor was SmCC, showing neuroendocrine differentiation such as pseudo-rosette, positive Grimelius stain, and chromogranin A/NCAM/synaptophysin immunostaining. Proximal to this tumor, non-invasive UC spread superficially over entire length of the ureter to the renal pelvis. Abrupt transition from invasive SmCC to non-invasive UC was observed in the middle of the ureter. Post-operative adjuvant chemotherapy was discouraged due to senile dementia of the patient. The patient died nine months after the operation because of systemic progression of cancer.