ß-catenin and Wnt signaling pathways have been found to play an important role in the tumorigenesis of solid pseudopapillary neoplasm of the pancreas, and their constitutive activation due to adenomatous polyposis coli gene inactivation in familial adenomatous polyposis may explain the relationship between familial adenomatous polyposis and solid pseudopapillary neoplasm of the pancreas. This evidence concerns the gene APC and Solid Pseudopapillary Neoplasm of the Pancreas.