[Immune-mediated thrombotic thrombocytopenic purpura with recurrent remission achieved by fresh frozen plasma transfusion and steroid therapy without plasma exchange].

A 26-year-old man presented in 2002 with petechiae, hemolytic anemia, and thrombocytopenia, raising suspicion for thrombotic thrombocytopenic purpura (TTP). His condition improved with plasma exchange, fresh frozen plasma (FFP) transfusion, and prednisolone. He was diagnosed with thrombotic microangiopathy and subsequently experienced multiple relapses, all treated successfully with FFP transfusion and prednisolone. During the sixth relapse in December 2018, a marked reduction in ADAMTS13 activity was detected, confirming the diagnosis of TTP. At the ninth relapse in June 2022, ADAMTS13 inhibitor testing was negative, and congenital TTP was considered as a differential diagnosis. However, repeated testing at another institution confirmed the presence of ADAMTS13 inhibitor, leading to the final diagnosis of immune-mediated TTP. After rituximab therapy, ADAMTS13 inhibitor became undetectable, and the patient has remained in remission for three years. This clinical course is atypical for immune-mediated TTP, as recurrent relapses were successfully managed with FFP transfusion and short-term prednisolone. This case provides important insights into the diagnosis and management of immune-mediated TTP.