Abstract
Acquired inhibitors of coagulation factor XI (FXI) are a rare cause of bleeding disorders, typically associated with autoimmune diseases or malignancies. Although uncommon, these inhibitors can lead to severe bleeding, which can be difficult to manage. A limited number of cases have been reported where acquired FXI inhibitors are associated with malignancy. This case report presented a rare occurrence of acquired coagulation FXI inhibitors in a 60-year-old male with sigmoid colon adenocarcinoma. The patient experienced severe postpolypectomy gastrointestinal bleeding and was diagnosed with FXI inhibitors after laboratory tests revealed prolonged activated partial thromboplastin time (aPTT) and reduced activities of factors IX, XI, and XII. The patient underwent surgery, and life-threatening hemorrhagic shock developed. He was reoperated, and treatment with recombinant factor VIIa (rFVIIa), tranexamic acid, and oral corticosteroids was initiated. The therapy successfully controlled the bleeding and resolved the inhibitor. This case highlights the risk of severe bleeding in patients with acquired FXI inhibitors and emphasizes the importance of early diagnosis and personalized treatment. Regular monitoring is essential due to the risk of relapse, particularly in cases associated with malignancy.