The number of diagnoses of renal cell carcinoma has increased over the past two decades because of the incidental detection of small renal tumours resulting from increased use of computed tomography [1,2]. There are distinct subtypes of renal cell carcinoma (RCC), and the biological aggressiveness and prognoses for these subtypes have been documented. Clear-cell RCC is the most common RCC subtype, followed by papillary RCC, chromophobe RCC and unclassified RCC. Collecting duct carcinoma is a rare and highly malignant type of RCC. Although most enhancing renal masses in adults are RCC, a significant percentage are benign (commonly oncocytoma), and these benign tumours cannot be distinguished from malignant tumours based on our standard imaging technology alone.