Introduction:
Acquired hemophilia A is a rare coagulation disease which can cause significant morbidity. We reported an acquired hemophilia A patient presenting with forearm compartment syndrome.

Materials and Methods:
An 88-year-old woman with past history of hypertension and dementia was referred to our emergency department with atraumatic right forearm swelling and extensive ecchymosis. Acute compartment syndrome was diagnosed based on typical clinical signs. Urgent forearm fasciotomy was performed, but subsequent generalized massive bleeding from open wound happened despite several attempts in hemostasis. Hematologist was consulted, and extensive laboratory workup showed a residual factor VIII activity of 1.4% and presence of factor VIII autoantibodies in 4.9 BU/ml. Acquired hemophilia A was diagnosed.

Results:
After acquired hemophilia A diagnosed, interdisciplinary team care was initiated. In the aspect of plastic surgery, diminishing wound size as soon as possible was primary goal. At the same time, activated prothrombin complex concentrate (FEIBA) and steroid were prescribed to achieve adequate hemostasis and eliminate inhibitors as per hematology expertise. Forearm swelling subsided in the following days and wound closure successfully on postoperative day 8, but persistent oozing from suture wound was still noted. Recombinant human factor VIIa (rFVIIa) and cyclophosphamide were then used. Adequate hemostasis was achieved under interdisciplinary team cooperation.

Conclusion:
Acute compartment syndrome can cause devastating morbidity and mortality. We presented an elderly woman with atraumatic compartment syndrome and diagnosed as acquired hemophilia A. Acquired hemophilia A should be considered in atraumatic compartment syndrome patients, especially elderly, and interdisciplinary treatment is necessary.