Urothelial carcinoma of the renal pelvis with squamous and sarcomatoid differentiation complicated by hydronephrosis and pyelonephritis: a case report and literature review.

Background: Renal pelvic urothelial carcinoma with multiple histological variants co-occurs with hydronephrosis and pyelonephritis extremely rarely. The diagnosis of renal pelvic urothelial carcinoma can be complicated by these conditions, leading to delayed or missed diagnosis or misdiagnosis.

Case presentation: We report the evolutionary course of a rare case of renal pelvic urothelial carcinoma containing squamous and sarcomatoid differentiation associated with hydronephrosis and pyelonephritis in a low-functioning kidney. Preoperative clinical and imaging manifestations were highly suggestive of hydronephrosis and pyelonephritis; however, all corresponding therapeutic measures failed. Eventually, nephrectomy was performed, and postoperative pathological examination revealed renal pelvic urothelial carcinoma with squamous and sarcomatoid differentiation. Further residual ureter and bladder cuff resection was refused by the patient. Regular cisplatin-based postoperative chemotherapy and bladder perfusion were arranged, and cystoscopy and imaging examinations were performed regularly for follow-up.

Conclusion: Hydronephrosis and pyelonephritis can mask the typical clinical and imaging manifestations of renal pelvic urothelial carcinoma. Renal pelvic malignancy should be considered in patients with intractable pyelonephritis and hydronephrosis. There is no standard treatment for renal pelvic carcinoma with multiple pathological types. Radical surgery is considered an appropriate option and should be performed as early as possible. Chemotherapy and immunotherapy may improve patient survival.