Primary small cell carcinoma of kidney after renal transplantation: a case report and literature review.

Extrapulmonary small cell carcinoma (EPSCC) is a rare neoplasm comprising 2.5% to 5% of small cell carcinomas (SCCs). Bladder SCC is the most common site of genitourinary tract. Primary renal SCC is extremely rare. We report a case of primary SCC of the kidney which is rarely reported in the urinary tract and presents an aggressive clinical picture. A 59-year-old female visited a urologic clinic with complaint of persistent left flank soreness 10 years after undergoing renal transplantation. Abdominal computed tomography showed a left renal pelvis tumor. After the patient received left nephroureterectomy with bladder cuff resection, her pathology results showed SCC. After surgery, she received adjuvant systemic chemotherapy, and her recovery has been uneventful as of 8 months. Primary renal SCC presents with an advanced tumor stage and a short median survival period, therefore early intervention and close follow-up are recommended.