RESUMO
INTRODUCTION: Acquired hemophilia-A (AHA) is a rare but potentially life-threatening impaired coagulation disorder characterized by the development of autoantibodies against clotting factor VIII. Only a few case reports have been experienced with influenza vaccine-triggered AHA. Here, we report a case of severe hemorrhagic disorder due to AHA following influenza vaccine, which was successfully treated. PATIENT CONCERNS: The patient presented to the emergency department because of several severe, progressively worsening bruises after receiving the influenza vaccination. Consequently, the patient required intubation due to nasal-oral bleeding, which compromised the airway, and retroperitoneal hemorrhage with shock also developed. DIAGNOSIS: AHA was confirmed through a coagulation factor assay, including coagulation activity and antibody testing, which is possibly triggered by influenza vaccination. INTERVENTION: Low-dose cyclophosphamide and hydrocortisone were prescribed until activated partial thromboplastin time showed normal levels. Coagulation factor VIIa was administered, and aggressive blood transfusion was carried out concurrently to address the blood loss. OUTCOMES: The upper airway bleeding subsided and bleeding tendencies had been corrected to normal. The patient was smoothly weaned from the ventilator and recovered from critical illness. She was then discharged on the 19th day. LESSONS: The activated partial thromboplastin time mixing test can be performed immediately to establish the initial differential diagnosis and treatment plan for severe coagulopathy. AHA may be triggered by vaccination, with the hypothesis of activation of autoantibodies and molecular mimicry; this mechanism should be further studied.
