ABSTRACT
Thrombotic thrombocytopenic purpura (TTP) is a clinical syndrome characterized by micro-angiopathic hemolytic anemia, thrombocytopenia, fever, renal disorders, and neurological manifestations. Its clinical course is rapid and the mortality rate is high if untreated or relapse occurs. Previous studies reported that rituximab, a monoclonal antibody for CD20 surface antigen on B lymphocytes, may be effective in treating idiopathic TTP that is refractory to plasma exchange or relapses after remission. A 27-year-old Vietnamese man presented with fever and fatigue starting 3 days earlier, which was diagnosed as idiopathic TTP. To overcome his poor responsiveness to combined therapy using steroids and plasma exchange, rituximab was considered. In the current case, the patient was treated with a lower dose of rituximab, instead of the conventional 375 mg/m2/week, and achieved successful remission.