Introduction and importance: Primary small cell neuroendocrine carcinoma (SCNEC) in the urinary tract represents less than 0.5 % of urinary tract cancers, and bladder or prostate are the most common sites. Early diagnosis and treatment of ureteral SCNECs are challenging due to nonspecific clinical symptoms and radiographic findings. Case presentation: Here, we described a diagnostic and therapeutic challenge of a 56-yearold male with recurrent right flank pain that did not relieve with analgesics alone. The patient underwent several non-invasive to invasive procedures revealing nonspecific inflammation pathology of the ureter that later developed into protruded papillary mucosa resembling polypoid cystitis. Later, an abdominal multi-slice computed tomography examination suggested a malignant mass and was confirmed as SCNEC from the pathological analysis. After several successful chemotherapy cycles and surgical procedures, cancer reoccurred, and the patient's general condition deteriorated. He passed away a year after a radical cystoprostatectomy and nephroureterectomy on his right side. Clinical discussions: The occurrence of primary SCNEC is a highly uncommon phenomenon. As SCNEC arises from pluripotent stem cells that have differentiated into neuroendocrine cells, some patients may exhibit paraneoplastic syndrome. The patient's prognosis of this tumor is poor, even for patients in the earliest phases, because SCNEC is characterized by highly aggressive local invasion and distant metastases. Conclusions: This case highlights the importance of accurate early diagnosis and treatment of recurrent flank pain and considering the possibility of a malignant tumor as the cause of obstruction.
- Case report