A Case of Primary Mucinous Adenocarcinoma of the Renal Pelvis: A Rare Occurrence

Abstract

Adenocarcinoma represents only 1% of renal pelvis malignancies and can have three subtypes: tubulovillous, mucinous, and papillary non intestinal. Primary mucinous adenocarcinomas are very rare in the renal pelvis. We report a case of a 62-year-old male patient who presented with bilateral dull aching flank pain for 15 years. No flank tenderness was observed on clinical examination. Magnetic Resonance Imaging of the Kidney, Ureters, and Bladder (MRI KUB) showed marked dilation of the left kidney's pelvicalyceal system with irregular thinning of renal parenchyma, as well as a large filling defect. Percutaneous Nephrolithotomy (PCNL) obtained gelatinous material, and the Carcinoembryonic Antigen (CEA) level was found to be high. The patient underwent left radical nephrectomy, and gross examination of the kidney revealed staghorn calculi and multiple cavities filled with pus and gelatinous material. Microscopic examination showed atypical glands infiltrating the parenchyma with abundant extracellular mucin. Immunohistochemical (IHC) examination showed cytoplasmic positivity for CK7, CK20, and CEA, while PAX8 and GATA3 were negative. The Ki67 labeling index was more than 20%. The case was diagnosed as mucinous adenocarcinoma of the renal pelvis.