Renal collecting duct carcinoma in an 8-year-old child.

A fatal collecting duct carcinoma, presenting with pleural metastases, arose from the right kidney in an 8-year-old child. A distal nephron origin of the tumor is supported by positive tumor staining with Ulex europaeus and Arachis hypogaea, and a lack of staining with Tetragonolobus lotus. The ultrastructural features of short stubby microvilli, smooth basal cell membranes, and lateral membrane infoldings also support a distal nephron origin (inner most inner medullary collecting duct). This rare childhood renal neoplasm behaved similarly to that reported in adults with metastatic disease at presentation and a short fatal clinical course.