Relapse of acquired hemophilia A following COVID-19

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Acquired hemophilia A (AHA) is a rare disease in which an autoantibody causes bleeding by interacting with and inhibiting the coagulation activity of endogenous factor VIII (FⅧ). Most cases of AHA are idiopathic, and other causes include autoimmune diseases, malignant tumors, pregnancy, drugs, and viral infections. An 86-year-old man was diagnosed with AHA based on the following results: activated partial thromboplastin time (aPTT) extension of 130.7 seconds, inhibitor pattern by mixing study, endogenous factor VIII (FⅧ) level at <1%, and FⅧ inhibitor titer at >5.1 Bethesda units (BU). The activity of von Willebrand factor (vWF) decreased (<10%), which was considered to be a complication of acquired von Willebrand syndrome (AVWS). The patient was started on prednisolone, and the inhibitor level eventually became negative. vWF values also became normal. However, 1 year later, he was hospitalized due to Coronavirus disease 2019 (COVID-19). His blood test showed an aPTT extension of 110.5 seconds, FⅧ level at 4%, and FⅧ inhibitor titer at 0.8 BU; thus, he was diagnosed with a relapse of AHA. After the administration of corticosteroid and remdesivir, he recovered from COVID-19 and AHA. The inhibitor level became negative on the 9th day of admission. Several articles have reported that COVID-19 infection and vaccination are implicated with AHA. We suggest that the aPTT should be measured when patients with AHA are infected with SARS-CoV2 to confirm AHA relapse.