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Multifocal sarcomatoid urothelial carcinoma of the renal pelvicalyceal system and ureter: A diagnostic dilemma

Sarcomatoid urothelial carcinomas (SUCs) are characterized by intimately mixed malignant epithelial and malignant mesenchymal components. We present a case of a multifocal SUC in the left pelvicalyceal system of the kidney and the left ureter. SUC although rare should be included in the differential diagnosis of multifocal tumors of the renal pelvis and ureter. Immunohistochemistry is essential to confirm the diagnosis and rule out other differentials including pure sarcoma, sarcomatoid variant of renal cell carcinoma, and pseudosarcomatous mesenchymal proliferation.