A Rare Case of Acquired Thrombotic Thrombocytopenic Purpura Triggered by Acute Pancreatitis.

Acquired thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy with varied etiology and manifestations. It is uncommon for acute pancreatitis to trigger TTP. A 59-year-old man hospitalized with acute pancreatitis developed fever, acute kidney injury, thrombocytopenia, and microangiopathic hemolytic anemia (MAHA) on his second day in the hospital. Based on clinical suspicion and a high PLASMIC score indicating a severe deficiency in ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif no. 13) activity, a presumptive diagnosis of TTP was made. He was treated with plasmapheresis with improvement in his hemoglobin and platelet count. Severely deficient ADAMTS13 activity causing accumulation of large von Willebrand factor (VWF) multimers and subsequent formation of platelet rich microthrombi are thought to be the mechanisms of development of TTP. Proinflammatory mediators released during the systemic inflammatory response seen in acute pancreatitis can promote VWF activity and inhibit ADAMTS13 activity. Diffuse endothelial injury as a result of the inhibition of vascular endothelial growth factor (VEGF)-mediated endothelial protection as well as production of excessive reactive oxygen species during an episode of acute pancreatitis also contributes to the pathogenesis of TTP. Thrombocytopenia and MAHA in a systemic inflammatory state should raise the suspicion for TTP. The PLASMIC score can further aid in the diagnosis and early initiation of plasmapheresis, which is key to the outcome.