Familial Adenomatous Polyposis Complicated by Acute Myelogenous Leukemia

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder characterized by the appearance of multiple colorectal adenomatous polyps and propensity for evolving into adenocarcinoma, typically in early adulthood. We present a case of a 38-year-old man with a one-year history of bloody stool, found to have innumerable polyps throughout the colon and therefore diagnosed with FAP. Completed blood count with differential revealed blasts, a finding confirmed via a peripheral blood smear; a follow-up bone marrow biopsy also showed blasts and he was diagnosed with acute myeloid leukemia (AML). To our knowledge, FAP and AML occurring in the same patient were reported only once in the literature. In our patient and the previously reported case, it is assumed that FAP occurred first and AML developed later; no family history of FAP was noted in either patient. This case raises the question of whether a sporadic FAP is more likely to lead to AML compared to the classic FAP.