Brunner's gland hamartoma with incipient ductal malignancy. Report of a case.

A duodenal tumor mainly composed of Brunner's glands was surgically resected in a 54-year-old man complaining of hematemesis and melena. Histologic examination of the specimen revealed a lobular pattern of either ducts or glandular acini, with Paneth cells; smooth muscle fibers, fat tissue and well formed vascular channels were seen in the stroma. These aspects are more suggestive of a hamartomatous rather than an adenomatous lesion. Moreover, the epithelium in some ducts showed early malignant transformation, which is a feature never observed in previous reports.