Comments: This rare renal tumor shows differentiation towards medullary collecting tubules. It is usually centered on the medulla with extension towards the cortex. It has a tubulo-papillary architecture accompanied by substantial desmoplastic response.
Comments: The tumor cells are arranged in duct-like structures, irregular nests or infiltrate singly. Hobnail appearance, seen clearly in this duct, is a helpful diagnostic feature. The prognosis is generally poor.
