title: 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.
authors.affiliation: Department of Hematology and Oncology, Miyagi Children's Hospital, Aoba-ku, Sendai, Japan. asatoh@miyagi-children.or.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sato
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hoshi
authors.forename: Masaei
authors.initials: M
authors.lastname: Onuma
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Sato
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Tsunematsu
authors.forename: Ayami
authors.initials: A
authors.lastname: Isonishi
authors.forename: Masanori
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujimura
authors.forename: Masue
authors.initials: M
authors.lastname: Imaizumi
mesh_terms: D051722:ADAM Proteins / Q000172:deficiency / Q000276:immunology*; D000071120:ADAMTS13 Protein; D001323:Autoantibodies / Q000276:immunology*; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology* / Q000628:therapy; D003131:Combined Modality Therapy; D003937:Diagnosis, Differential; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007223:Infant; D008297:Male; D008775:Methylprednisolone / Q000627:therapeutic use; D017713:Platelet Transfusion; D011239:Prednisolone / Q000627:therapeutic use; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000175:diagnosis; D011697:Purpura, Thrombotic Thrombocytopenic / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology* / Q000628:therapy
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G; D007166:Immunosuppressive Agents; D011239:Prednisolone; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human; D008775:Methylprednisolone