A 9-MONTH-OLD INFANT WITH ACQUIRED IDIOPATHIC THROMBOTIC THROMBOCYTOPENIC PURPURA CAUSED BY INHIBITORY IgG-AUTOANTIBODY TO ADAMTS13

Abstract

Although acquired idiopathic thrombotic thrombocytopenic purpura (ai-TTP) is rare in children, the authors present the case of a 9-month-old boy with ai-TTP showing severe deficiency of ADAMTS13 activity by its inhibitory IgG-autoantibody (4.8 Bethesda units/mL). Plasma exchange therapy was clinically effective but transient. Deficient activity of ADAMTS13 with the presence of its inhibitor persisted for 7 months after the initial diagnosis. However, other laboratory findings improved gradually with steroid (pulse) therapy. The hitherto insufficiently characterized clinical settings of ai-TTP during early childhood underscore the importance of measuring ADAMTS13 activity and its inhibitors for differential diagnosis in patients with thrombocytopenia of unknown etiology.

Keywords :

• acquired TTP
• ADAMTS13
• infancy
• von Willebrand factor-cleaving protease

ACKNOWLEDGMENT

This work was supported in part by grants-in-aid for scientific research from the Ministry of Education, Culture, Sports, Science and Technology and from the Ministry of Health, Labor and Welfare of Japan.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.