Advanced gastroduodenal polyposis with ras mutations in a patient with familial adenomatous polyposis.

Upper gastrointestinal polyps are being recognized with increasing frequency in patients with familial adenomatous polyposis. Duodenal and periampullary adenomas are the most common type and have poorly understood but definite malignant potential. In contrast, the majority of polypoid lesions in the stomach are benign fundic gland polyps. We report a patient with familial adenomatous polyposis who developed dysplasia in a large exophytic hyperplastic gastric tumor that appeared to arise on a background of diffuse fundic gland polyposis and presented with anemia, hypoalbuminemia, and a protein-losing enteropathy. A large periampullary adenoma also was present. Using the polymerase chain reaction with mismatched primers, a GGT to TGT Kras codon 12 mutation was detected within areas of severe dysplasia in the gastric tumor and in the periampullary adenoma. This case serves to further highlight the spectrum of clinical, pathologic, and molecular features of premalignant upper gastrointestinal tract lesions in patients with familial adenomatous polyposis.