Renal small cell neuroendocrine carcinoma: a case report and literature review

Renal small-cell neuroendocrine carcinoma (renal SCNEC) is an exceedingly rare and highly aggressive tumor of the urinary system, originating from peptidergic neurons or neuroendocrine cells. The disease often presents with insidious clinical symptoms and lacks specific imaging features, which can delay diagnosis and predispose to distant metastases. Here, we report a case of renal SCNEC and describe its diagnosis, treatment, and outcomes, aiming to enhance clinical understanding and management of this rare condition.

We report the case of a 64-year-old man who presented with left-sided flank pain without hematuria. Imaging studies revealed a mass in the left kidney. Percutaneous biopsy and immunohistochemical analysis confirmed the diagnosis of SCNEC. The patient received two cycles of neoadjuvant chemotherapy consisting of cisplatin and etoposide, followed by laparoscopic radical nephrectomy. Postoperative chemotherapy was administered according to the planned regimen. During 16 months of follow-up, no evidence of recurrence was observed.

Prompt recognition and diagnosis of renal SCNEC are crucial to prevent misdiagnosis and delayed treatment. Diagnosis relies on histopathology, immunohistochemistry, and careful evaluation of common metastatic sites, including lymph nodes, liver, and bones. Treatment should be individualized based on disease stage and the patient's condition; for locally advanced renal SCNEC, platinum-based chemotherapy combined with radical surgery may be considered as part of a multimodal treatment strategy in selected patients. Given the rarity of this tumor, multidisciplinary collaboration and evidence-based research are essential to optimize management and establish standardized treatment guidelines.

For patients with locally advanced renal SCNEC, platinum-based chemotherapy combined with radical surgery may provide a therapeutic option after multidisciplinary evaluation.