A case of primary ureteral small cell carcinoma

Abstract

Background : We report the cytological findings in voided urine and pelvic/ureteral urine samples of a case of primary ureteral small cell carcinoma in which the histological type could not be determined preoperatively.

Case : A man in his 70 s visited our hospital with complaints of diarrhea and lower abdominal pain. Abdominal computed tomography revealed left hydronephrosis and a nodular lesion in the middle portion of the left ureter. High-grade urothelial carcinoma was suspected because atypical cells with a high nuclear-to-cytoplasmic ratio and dense nuclear chromatin were detected in urine cytology and histopathological examination of biopsy specimens. We performed total excision, and postoperative histopathology of the resected tumor revealed tumor cells with scant cytoplasm and round nuclei. Therefore, the patient was diagnosed as a case of ureteral small cell carcinoma.

Conclusion : Because of the poor prognosis of ureteral small cell carcinoma, it is crucial to differentiate it from urothelial carcinoma. Although cytological differentiation between these two cancer types is difficult, immunocytochemical staining should be considered for further differentiation if the findings are indicative of small cell carcinoma, such as atypical cells with scant cytoplasm or nuclear molding.