63-year-old male with a nodule at the renal pelvis showing CK7+, GATA3+, HMWCK+, Vimentin- on immunohistochemistry. What is the most likely diagnosis?

• A. Urothelial carcinoma
• B. Renal cell carcinoma
• C. Prostate adenocarcinoma
• D. Squamous cell carcinoma

Answer: (A)

Immunohistochemical profile points to urothelial differentiation. GATA3 is a sensitive marker for urothelial epithelium, and its positivity strongly supports a urothelial origin. CK7 is commonly expressed in urothelial carcinomas, and high molecular weight cytokeratin (HMWCK) positivity is typical for urothelial tumors as well. The absence of vimentin further supports this over renal cell carcinoma, which more often shows vimentin positivity and a different pattern of markers (often PAX8, RCC markers). The renal pelvis location also fits urothelial carcinoma, since the urothelium lines the renal pelvis.

In contrast, renal cell carcinoma would be more likely to express RCC-associated markers and often be vimentin-positive, with a profile not driven by GATA3 positivity. Prostate adenocarcinoma would typically express prostate markers (PSA, PSAP) and not show this urothelial-like marker combination. Squamous cell carcinoma could show high‑mMW cytokeratins but would not be as strongly supported by GATA3 positivity in this context.

So, the combination of CK7+, GATA3+, HMWCK+, and Vimentin− in a lesion of the renal pelvis most strongly supports urothelial carcinoma.