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Keywords:

  • thrombotic thrombocytopenic purpura;
  • ADAMTS13;
  • von Willebrand factor;
  • rituximab

Abstract:

Objective: This report describes the experience of a case of atypical thrombotic thrombocytopenic purpura (TTP) whose diagnosis was based on severe deficiency of the von Willebrand factor (vWF) cleaving metalloprotease ADAMTS13.

Methods: The level of ADAMTS13 activity, the titer of the inhibitors of this protease and the size distribution of vWF multimers in plasma samples were analysed in a patient with recurrent episodes of dizziness and blurred vision.

Results: In the absence of thrombocytopenia or microangiopathic hemolysis, diagnosis of TTP was established by demonstration of very low ADAMTS13 activity levels and the presence of inhibitors of this protease. After rituximab therapy decreased the inhibitor titer and increased the ADAMTS13 level, the patient has had no relapse of ischemic symptoms in the following 16 months.

Conclusions: Acute neurological deficits may occur in TTP without concurrent thrombocytopenia or microangiopathic hemolysis. The role of rituximab for patients with TTP deserves further exploration.