Hypersensitivity to plasma exchange in a patient with thrombotic thrombocytopenic purpura.

To a limited extent, thrombotic thrombocytopenic purpura (TTP) in addition to its clinical features is being defined nowadays with laboratory tests such as the assay for the Von Willebrand factor-cleaving protease (ADAMTS 13) and its antibody. We present a case report of a patient with TTP and idiopathic thrombocytopenic purpura (ITP) who had an elevated inhibitor level after plasma exchange. After instituting plasma exchange, patient improved clinically with a platelet count in the normal range. Subsequently, she developed an elevated ADAMTS antibody titer accompanied by a decline in platelet count despite continued exchange. She was successfully treated with a combination of steroids, rituximab and increased dose plasmapheresis. Based on this experience, we conclude that a drop in platelet count while patient is undergoing plasma exchange especially in an initial episode of TTP needs prompt institution of additional therapy to improve outcomes. This case also brings to attention the possibility of an underlying ITP in a patient with an initial diagnosis of TTP.