Reticulum-cell sarcoma is probably the most infrequent malignant lesion to be found in the duodenum. Since the original description of carcinoma of the duodenum by Hamberger,1 in 1746, numerous publications have appeared, many being of a single case, and the total and long experience of a single institution has not exceeded 31 cases. A review of the world literature by Brenner and Brown,2 in 1955, resulted in the collection of only 474 cases of carcinoma. Kleinerman and co-workers3 estimated the incidence of duodenal carcinoma found at necropsy to be 0.035%, based upon a collected series of 487,695 postmortem examinations. Other malignant lesions of the duodenum are also extremely rare, and these include lymphosarcoma, leiomyosarcoma, and carcinoids. In a series of 17 primary malignant lesions reported by Ochsner and Kleckner4 that had been collected over a period of 20 years, only one reticulum-cell sarcoma was included. In