Collecting duct carcinoma of the kidney

Six cases of renal epithelial neoplasms, which show atypical histological features previously described in cases of collecting duct carcinomas, are presented. The tumours were of a tubulo-papillary architecture, arose in the renal medulla and showed prominent infiltrating tubules with an associated desmoplastic reaction. Atypical hyperplastic changes were present in the medullary collecting ducts in five cases.