Papillary RCC: The "Hypo-Everything" Tumor

Papillary RCCs have a very distinct imaging appearance compared to the more common clear cell subtype.

Enhancement: They are classically hypovascular. On a multiphasic CT, they often enhance less than the normal renal cortex and far less than clear cell RCCs (which are avidly hypervascular). An enhancement increase of only 10–20 HU can sometimes make them tricky to distinguish from a hyperdense cyst.

MRI Signal: They are characteristically markedly T2 dark due to their dense architecture and frequently contain internal hemorrhage or hemosiderin.