DUODENAL ADENOMA OF GASTRIC FOVEOLAR PHENOTYPE IN THE SECOND PORTION OF THE DUODENUM

We describe a rare case of duodenal adenoma of a gastric phenotype in the second portion of the duodenum. An 85-year-old Japanese man with a history of left nephrectomy was admitted to our hospital with a cerebral transient ischemia attack. Screening upper gastrointestinal endoscopy revealed a subpedunculated polyp with a reddish, erosive, glossy appearance, and a granular surface just above the papilla of Vater in the second portion of the duodenum, which on biopsy was diagnosed as a hyperplastic polyp. Hypotonic duodenography revealed a subpedunculated polyp with irregular granular surface, measuring approximately 20 mm in size, in the second portion of the duodenum. Endoscopic total resection for biopsy was performed. The histopathological examination of the polypectomied specimens revealed an adenoma with moderate dysplasia mimicking gastric foveolar epithelium or hyperplastic polyp accompanied by abundant mucin production. Immunohistochemistry revealed a complete gastric phenotype, suggesting it had probably arisen from heterotopic gastric mucosa. The present case is the eleventh case of duodenal neoplasia arising from heterotopic gastric mucosa and the sixth case of neoplasia with gastric phenotype found in the second portion of the duodenum reported in the world.