A report of a Wilms' tumor with hitherto undescribed ultrastructural and histochemical features is presented. The unique features conform structurally, and to some extent chemically to autophagosomes, which occur in similar abundance only in granular cell myo-blastoma, recently considered to be derived from neural elements. The implication of this common structural feature readdresses attention to the work of Masson, who originally theorized a neurectodermal origin for the Wilms' tumor.