Sarcomatoid urothelial carcinoma of the renal pelvis: A case report and literature review.

Sarcomatoid urothelial carcinoma (SUC) of the renal pelvis is a rare, highly aggressive upper tract urothelial carcinoma variant. We report a 67-year-old man with persistent fever, gross hematuria, leukocytosis, and a renal pelvic mass with hydronephrosis and calculi. Fever persisted despite antimicrobial therapy and nephrostomy drainage until radical nephroureterectomy was performed. Postoperatively, fever and inflammatory indices normalized but recurred 1 month later; by 3 months, CT showed multiple intra-abdominal metastases with leukocytosis and neutrophilia. The patient died 4 months after surgery. This case suggests that persistent or recurrent fever with leukocytosis may reflect tumor activity rather than infection.