Familial Adenomatous Polyposis (FAP) Presenting as Iron Deficiency Anemia in a 33-Year-Old Female: A Case Report

Iron deficiency anemia is a common clinical concern in women of reproductive age. It presents as microcytic anemia and can be due to a limited number of causes including bleeding, malabsorption, intravascular hemolysis, or a mechanical heart valve. Familial adenomatous polyposis (FAP) is an inherited autosomal dominant disorder due to mutation in the adenomatous polyposis coli (APC) gene that can cause iron deficiency anemia due to GI malignancy, most notably colon cancer. Variation of mutations within the APC gene can cause different forms of FAP, such as Gardner syndrome. This syndrome presents with epidermoid cysts typically in unconventional locations such as the face, scalp, and extremities, as seen in our patient. We report a presentation of FAP in a 33-year-old Caucasian female who initially presented with iron deficiency anemia, hematochezia, and weight loss. Colonoscopy revealed hundreds of polyps within the colon, with two that were biopsied and reported as tubulovillous adenoma. The patient underwent a robotically assisted laparoscopic total proctocolectomy with ileal pouch-anal anastomosis, as well as a diverting loop ileostomy, and was given pain medication. She was referred to genetic counseling for her daughters and herself, which revealed a pathogenic variance in the APC gene.