[Acquired hemophilia A complicated by dipeptidyl peptidase-4 inhibitor-associated bullous pemphigoid].

A 72-year-old man developed dipeptidyl peptidase-4 inhibitor-associated bullous pemphigoid (BP) during treatment for type 2 diabetes mellitus and was administered prednisolone (PSL, 0.5 mg/kg). Despite PSL treatment at a daily dose of 19 mg/day, purpura appeared on his bilateral forearms 3 months later. He was diagnosed with acquired hemophilia A (AHA) based on a prolonged activated partial thromboplastin time, decrease in factor VIII activity, and the presence of factor VIII inhibitor. Immunosuppressive therapy (IST) comprising PSL (1 mg/kg) and cyclophosphamide (300 mg/week) did not reduce the inhibitor level, and he subsequently developed the complication of pneumonia caused by a fungal infection. Weekly rituximab (RTX) therapy (375 mg/m2) for 4 weeks not only reduced the inhibitor level, but also enabled a rapid PSL dose reduction. Finally, a coagulative complete remission was achieved with improvements in pneumonia and BP. The prevention of adverse events of IST is particularly important in patients with AHA, who have a high median age. Therefore, RTX-based IST may be safer for AHA patients with complicating infections.