[Transient acquired thrombotic thrombocytopenic purpura developed during bortezomib, lenalidomide, and dexamethasone therapy for multiple myeloma].

A 59-year-old woman was diagnosed with symptomatic Bence Jones protein, lambda (λ) type, associated with multiple myeloma (BJP-λ MM). Considering her renal dysfunction, she initially received bortezomib and dexamethasone. After renal function improved, she received one cycle of bortezomib, lenalidomide, and dexamethasone (BLD) therapy and achieved stringent complete response. She presented with general fatigue and jaundice before the second cycle of BLD. Laboratory testing revealed: total bilirubin, 4.8 mg/dl; indirect bilirubin, 4.1 mg/dl; lactate dehydrogenase, 978 U/l; hemoglobin, 7.4 g/dl; haptoglobin, <10 mg/dl; platelet count, 23,000/µl; and creatinine, 0.96 mg/dl. A hemogram revealed 1% schistocytes. ADAMTS13 activity was undetectable and the ADAMTS13 inhibitor level was 1.8 Bethesda units. A diagnosis of acquired thrombotic thrombocytopenic purpura (aTTP) was made, and treatment was initiated with prednisolone and rituximab. Plasma exchange was not performed because thrombocytopenia did not progress. The first dose of rituximab restored platelet count, and ADAMTS13 inhibitor became undetectable. The clinical course in this case was consistent with drug-induced aTTP.