BACKGROUND
Acquired hemophilia A (AHA) is a rare but potentially life-threatening condition caused by autoantibodies against factor VIII. It often presents in older adults and its presentation can range from isolated lab abnormality of prolonged activated partial thromboplastin time (aPTT) without bleeding to mild bleeding or spontaneous vs disproportionate life-threatening bleeding. Delayed diagnosis is frequent due to the rarity of the condition and propensity to attribute bleeding to other common causes, such as falls.
CASE REPORT
A 92-year-old woman with recurrent ground-level falls presented with severe right lower extremity pain of several weeks’ duration. She was not on any anticoagulant or anti-platelet agent. Computed tomography angiography demonstrated bilateral lower extremity intramuscular hematomas. She had 2 prior admissions for falls within 6 months, including a fall leading to intramuscular hematoma, which was conservatively managed without evaluation of coagulopathy. During current admission, prolonged aPTT prompted further workup, revealing low factor VIII activity of 5% and a high factor VIII inhibitor titer of 15.6 Bethesda Units, establishing the diagnosis of acquired hemophilia A. Bleeding control required sequential bypassing agents, corticosteroids, rituximab, cyclophosphamide, and eventually emicizumab.
CONCLUSIONS
This case highlights how recurrent or disproportionate intramuscular hematomas following even minor trauma, such as a ground-level fall, in the absence of risk factors such as anticoagulant use, may prompt evaluation for underlying coagulopathy such as AHA. Basic coagulation testing including prothrombin time and aPTT can help screen patients who warrant additional coagulopathy evaluation. Timely diagnosis is critical to avoid life-threatening bleeding complications.

Keywords: Autoimmune Diseases; Bias, Implicit; Factor VIII; Frail Elderly; Hematoma; Hemophilia A