Familial adenomatous polyposis (FAP) is a rare syndrome characterized by the presence of hundreds to thousands of colorectal adenomas and is responsible for less than 1% of all colorectal cancers. The syndrome is also characterized by extra-colorectal features including amongst others upper gastrointestinal tract polyps and desmoid tumors. The syndrome is inherited by an autosomal dominant gene, the adenomatous polyposis coli (APC) gene. We present the physical history, clinical presentation, diagnosis and treatment of a patient with a novel germline APC mutation, the W421X mutation, which resulted in FAP presenting with about a hundred colorectal polyps, gastric hyperplastic polyps and multiple aggressive intra-abdominal and extra-abdominal desmoid tumors.