Thrombotic Thrombocytopenic Purpura Without Evidence of Microangiopathic Hemolytic Anemia: A Case Report

Diagnosis of thrombotic thrombocytopenic purpura (TTP) is challenging due to varied clinical presentations and is primarily based on ADAMTS13 activity assay, however clinical suspicion to include TTP as a potential diagnosis relies on multiple scoring systems all involving hemolysis as a prime feature. Here, we report a case of TTP without any evidence of microangiopathic hemolytic anemia (MAHA). A 65-year-old male admitted with a Glasglow come scale of 3 was intubated and sedated on admission. Complete blood count was concerning for a hemoglobin (Hb) of 5.8 g/dL, and a platelet count of 76 k/µL. The patient had a bleeding episode while placing a central line; the repeat platelet count was found to be 35 k/µL, further dropping to 14 k/µL the next day. Coagulation studies now reflected PT of 19.8 sec, aPTT of 38.7 sec, and fibrinogen of 212 mg/dL. The peripheral smear showed no evidence of hemolysis. TTP was kept low on the differential and haematological anomalies were attributed to possible disseminated intravascular coagulation (DIC) from sepsis and liver disease. ADAMSTS13 was incidentally checked upon admission, later resulting in <5% activity with a Bethesda titer inhibitor of 3.2. The patient was immediately initiated on plasmapheresis along with prednisone. Additionally, rituximab and caplacizumab were added. Plasmapheresis was continued for ten sessions until the platelet count reached 167 k/µL. At the time of discharge, laboratory values revealed platelets of 251 k/µL and hemoglobin of 8.8 g/dL. We recognize that the diagnosis of TTP is challenging because of its diverse clinical manifestations and constrained availability of ADAMTS13 testing. Clinical prediction scores have been developed to estimate the pretest probability of severe ADAMTS13 deficiency, however, they all include the presence of MAHA. Atypical presentation of TTP has been previously acknowledged however continues to remain under-recognized.