A rare case of primary malignant small cell carcinoma in the ureter

Small cell carcinomas of the urinary tract are extremely rare, and few cases have been reported. Therefore, the clinical behavior of these tumors is poorly understood, and effective diagnostic methods and treatment modalities have not been established. We present a 72-year-old female who was admitted to the hospital complaining of left-side flank pain. An ill-defined, ovoid mass that originated from the ureter and caused complete obliteration of the left ureter was identified in the left pelvic cavity. Following an exploratory laparotomy and ureteral fistulation, we removed part of the tumor and left ureter for pathology analysis. However, the mass could not be resected completely because it had invaded the left bladder wall, left colon, upper rectum, and left uterine horn. Adjuvant chemotherapy was given after the pathologic diagnosis of primary small cell carcinoma of the distal ureter. After four cycles of combination chemotherapy, the patient died 5 months postoperatively due to severe pulmonary infection.