[Thrombotic thrombocytopenic purpura. Reduced activity of von Willebrand factor cleaving protease]

Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy. Besides anemia and thrombocytopenia, neurological impairment is common in TTP. A 42-year-old woman was admitted to a department of obstetrics/gynecology because of severe vaginal bleeding due to thrombocytopenia. After platelet transfusion, the patient developed a reduced level of consciousness, confusion, headache, and fever. CT scan did not show pathological changes. Transcranial Doppler sonography revealed increased blood flow velocities of all basal cerebral arteries. Because encephalitis was suspected the patient was transferred to the neurological department. CSF and cerebral magnetic resonance imaging studies were normal. Finally, the detection of schistocytes in the peripheral blood smear and the strong elevation of LDH led to the diagnosis of TTP. After plasma exchange over 3 consecutive days the patient achieved complete remission. The diagnosis was confirmed by laboratory tests (activity of ADAMTS13 <5%, IgG antibodies against ADAMTS13). Platelet transfusion may adversely affect the outcome of patients with suspected TTP. Severely deficient activity of the von Willebrand factor cleaving protease (ADAMTS13) is specific for thrombotic thrombocytopenic purpura.