Gastric involvement in juvenile polyposis associated with germline SMAD4 mutations: an entity characterized by a mixed hypertrophic and polypoid gastropathy.

Exclusively gastric form of juvenile polyposis associated with germline SMAD4 mutation is a rare clinical entity and is usually difficult to diagnose in the absence of colorectal lesions. We describe the phenotype of two unrelated cases of exclusive or predominant gastric expression of juvenile polyposis. Endoscopically, we found an unusual hypertrophic and polypoid gastropathy with abundant mucus adhering to the mucosal surface. Initially diagnosed as hyperplastic polyps, examination of gastric macrobiopsy specimens and identification of SMAD4 gene mutation in both cases confirmed the diagnosis. Close upper GI surveillance was proposed in case 1 and prophylactic total gastrectomy in the second one. Juvenile polyposis limited to the stomach is a rare condition that is linked to SMAD4 mutations. Such a diagnosis should be considered whenever a mixed, hypertrophic and polypoid gastropathy is encountered.