Thrombotic Thrombocytopenic Purpura Triggered by Acute Myeloid Leukemia: A Case Report.

BACKGROUND Acute myeloid leukemia (AML) is a myeloid progenitor malignancy characterized by clonal expansion of immature blasts. Complications of AML can result from disease-related or treatment-related complications and commonly include bleeding and disseminated intravascular coagulation. Thrombotic thrombocytopenic purpura (TTP) is a microangiopathy syndrome characterized by a mechanical hemolytic anemia and a consumptive thrombocytopenia resulting in end-organ damage from thrombotic occlusion of small vessels. CASE REPORT We describe a case of TTP at our institution that developed after diagnosis of AML, an exceedingly rare phenomenon with only one such documented case in the current literature. We were advised to see this patient after development of renal failure and encephalopathy. Suspicion for TTP was initially low, as our patient had a low pre-test probability of TTP by the PLASMIC score. Our patient was treated for disseminated intravascular coagulopathy, without response. Plasma exchange pheresis (PLEX) was eventually begun 3 days after presentation upon result of ADAMTS13 activity at 10%, with presence of inhibitor. ADAMTS13 activity levels were used to guide continuation of PLEX, given our patient's persistent pancytopenia. CONCLUSIONS Our case demonstrates the challenges of identifying and managing TTP in patients with concomitant hematologic malignancies. ADAMTS13 activity levels should be collected in patients presenting with evidence of hemolytic anemia, even if the pre-test probability of TTP is low.