Renal Cell Carcinoma Masquerading as Pyonephrosis - A Case Report of A Rare Presentation.

We describe here an atypical case of pyonephrosis which on further evaluation turned out to be a renal cell carcinoma (RCC). The clinical presentation of the patient was that of an infective etiology. However, the renal mass associated with renal vein thrombus and lung metastasis was later diagnosed based on the clinical deterioration of the patient even after insertion of percutaneous nephrostomy. In this case, an underlying renal cancer was probably complicated secondarily leading to pyonephrosis which was the initial presenting manifestation which led to a delay in diagnosis. Pyonephrosis is usually associated with Xanthogranulomatous pyelonephritis. Association of RCC with pyonephrosis is extremely rare and hence seldom reported. Our patient later on underwent radical nephrectomy and the histopathology report was suggestive of RCC. We have described here the clinical manifestations and diagnostic issues of such a case. This case provides evidence that RCC should be kept as one of the differentials in such patients.