A Rare Case of Acquired Haemophilia A Following Sigmoid Adenocarcinoma: Case Report and Literature Review

ABSTRACT Acquired haemophilia A (AHA) is a rare autoimmune bleeding disorder resulting from the development of inhibitory autoantibodies against factor VIII (FVIII). Malignancy is a recognised association, although colorectal cancer remains an uncommon underlying cause. We report a 68‐year‐old woman with sigmoid adenocarcinoma who developed severe postoperative haemoperitoneum associated with progressive activated partial thromboplastin time prolongation, an initial FVIII activity of 52 IU/dL that subsequently declined to 2 IU/dL, and development of an FVIII inhibitor measuring 9.7 BU. The case highlights diagnostic challenges associated with AHA, particularly the risk of delayed diagnosis and the complexities of balancing immunosuppressive intensity alongside haemostatic therapy. We then present a review of current literature to guide management for this rare condition and emerging therapies.