Thrombotic thrombocytopenic purpura developed after pegylated interferon treatment for hepatitis B infection

Abstract Background Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and organ ischemia. It is related to severe deficiency in ADAMTS13, which is usually acquired via ADAMTS13 autoantibodies or inherited via mutations of the ADAMTS13 gene. The etiology of acquired TTP including HIV infection, pregnancy, autoimmune disease, organ transplantation, drugs, malignancy and so on. Here, we firstly reported a patient diagnosed as acquired TTP after pegylated interferon therapy for hepatitis B and COVID-19 vaccination. Case presentation A 36-year-old male attended to our unit with a five-day history of intermittent hematuria and progressive fatigue on January 5th, 2022. He had a 13 years history of hepatitis B infection and undergone pegylated interferon treatment (which was paused for two months because of COVID-19 vaccination) for nearly 3 years. Laboratory evaluation revealed a haemoglobin level of 61 g/L, platelet count of 11 × 109/L, lactate dehydrogenase 2133 U/L. The direct and indirect Coombs test were both negative. On a peripheral blood smear, there were about 18.8% schistocytes. Meanwhile, the results of ADAMTS 13 activity and antibody were