Unusual endophytic non-enhancing tumour in the renal pelvis: a diagnostic dilemma.

Renal cell cancer (RCC) is incidentally detected on imaging in 50%-60% of cases. Among the RCCs, clear cell variant is most common and classically seen as heterogenous enhancing lesion on CT imaging. Hypoenhancing mass presents a diagnostic dilemma with differential diagnosis being urothelial carcinoma, fat poor angiomyolipoma, oncocytoma or rarer variants of RCC. Such cases require further evaluation in form of urine cytology or newer molecular diagnostic techniques. Here, we present a case of renal mass with minimal enhancement on CT scan and imaging features suggestive of upper tract urothelial cancer. Final histopathology revealed the mass to be chromophobe variant of renal cell carcinoma.