Collecting Duct Carcinoma Versus Renal Medullary Carcinoma An Appeal for Nosologic and Biological Clarity
Abstract
Collecting duct carcinoma was recognized as a distinctive type of renal cell carcinoma in 1986 by Fleming and Lewi1,2 on the basis of a description of 6 cases of high-grade, invasive adenocarcinoma, arising in the renal collecting system and showing characteristic tubulopapillary growth associated with prominent stromal reaction.2-4 Review of published series of collecting duct carcinomas shows a male predominance of B2:1, a laterality favoring the right kidney of B2:1, and an aggressive clinical course with survival of B50% at 3 years.5-7 Recent efforts have addressed the difficulty of distinction of collecting duct carcinoma from urothelial carcinoma of the upper tract, including by the use of immunohistochemistry.8,9 To encourage uniformity in this diagnosis, the newly reported International Society of Urological Pathology (ISUP) Vancouver Classification10 emphasizes diagnostic criteria, including the following: "(1) at least some of the lesion involves the medullary region; (2) there is a predominant formation of tubules; (3) a desmoplastic stromal reaction should be present; (4) cytologic features are high grade; (5) growth pattern is infiltrative; and (6) there is an absence of other typical renal cell carcinoma subtypes or urothelial carcinoma."