Diffuse gastric polyposis in a young patient with a giant retroperitoneal mass: A case report

Familial adenomatous polyposis (FAP) is characterized by hundreds of colonic adenomatous polyps and extraintestinal manifestations beginning in adolescence and early adulthood. It is also one of the most common hereditary colorectal cancer syndromes. In this case study, a rare phenotype of FAP associated with diffuse gastric polyposis, colon oligo-polyposis, and a massive retroperitoneal mass is described. The results expand on the current body of knowledge of FAP and may represent a new phenotypic expression of FAP. Accurate evidence-based surveillance and management recommendations for this disease require further research and evaluation.