Rare Case of Multilocular Cystic Renal Neoplasm of Low Malignant Potential with Chronic Pyelonephritis

Abstract

Multilocular Cystic Renal Neoplasm of Low Malignant Potential (MCRNLMP) represents a rare variant of clear cell (conventional) renal carcinoma. They constitute between 3-6% of clear cell Renal Cell Carcinoma (RCC). The RCC constitutes less than 1% of all renal tumours. The MCRNLMP has an excellent prognosis with no reports of recurrence or metastasis. Authors reported a case of 67-year-old male patient on account of its rarity, co-existing pyelonephritis and incidental detection of MCRNLMP. Differentiation between MCRNLMP, RCC variants and other cystic lesions with clear cells is important as prognosis, treatment differ markedly. Radiological Bosnaik classification of complex cysts in category IIF and III is challenging and requires microscopic examination for correct diagnosis. Histopathology shows cysts separated and fibrous septae having groups of clear cells with low grade nuclei. Immunohistochemistry with Carbonic Anhydrase-IX (CA-IX), Epithelial Membrane Antigen (EMA), Cytokeratin (CK7) and CD10 is confirmatory. Diagnosis requires detailed imaging studies, meticulous grossing of nephrectomy specimens, extensive sampling of cystic tissue to find clear cells and immunohistochemistry (IHC).