Primary carcinoids of the ileum and rectum. A simultaneous occurrence.

A patient had a simultaneous occurrence of an ileal and a rectal carcinoid. The ileal carcinoid, occurring in an area derived from primitive midgut, was argentaffin-positive; the rectal carcinoid, occurring in an area derived from primitive hindgut, was argentaffin-negative. To my knowledge, this is the first reported case of simultaneous ileum and rectal carcinoids; its uniqueness tends to support the concept of heterogeneity of origin of carcinoids in embryologically distinct regions.