Ureteral small cell carcinoma.

Ureteral small cell carcinoma is very rare; only eight cases have been reported in the literature. In this article, we report the ninth case of ureteral small cell carcinoma. A 79-year-old Japanese man presented with asymptomatic macrohematuria, and left nephroureterectomy was performed. The nonpapillary and broad-based tumor, which measured 3.7 x 3.7 x 2.0 cm, was seen in the lower portion of the left ureter just above the ureteral orifice. Microscopically, the tumor was composed of urothelial carcinoma and small cell carcinoma. Immunohistochemically, neoplastic cells of small cell carcinoma were focally positive for chromogranin A. In the normal ureteral mucosa adjacent to the tumor, some endocrine cells positive for chromogranin A and synaptophysin were identified. In conclusion, we suggest that endocrine cells in the ureteral urothelial epithelium may be precursor cells of ureteral small cell carcinoma.