Thrombotic microangiopathy due to multiple autoantibodies related to antiphospholipid syndrome.
BACKGROUND
Antiphospholipid syndrome (APS) is a rare disorder in children. More than half of childhood APS occurs as secondary APS complicated by systemic lupus erythematosus (SLE) and other autoimmune diseases.


METHODS
We encountered a boy with SLE who presented with thrombotic microangiopathy (TMA) due to APS. He was initially diagnosed with SLE and treated with methylprednisolone pulse therapy. However, his renal function rapidly deteriorated. Since poikilocytes were detected, we suspected that his condition was complicated by TMA or APS. Urgent plasma exchange, continuous hemodialysis, and intravenous cyclophosphamide saved the patient and his renal failure ameliorated. A renal biopsy performed at the onset of disease showed multiple microvascular thrombi, diffuse mesangiolysis, and cortical necrosis compatible with TMA. He was positive for anticardiolipin antibody, anti-β2-glycoprotein I antibody, and lupus anticoagulant as well as anti-phosphatidylserine-prothrombin complex IgG antibody (aPS/PT). Anti-a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) antibody was negative and ADAMTS13 activity was normal. The aPS/PT is thrombogenic and is a newly discovered lupus anticoagulant.


CONCLUSIONS
Childhood TMA due to APS has rarely been reported. To the best of our knowledge this is the first report of pediatric TMA due to APS with positive aPS/PT. Physicians need to be aware of aPS/PT in pediatric APS and/or SLE.
Division of Nephrology and Rheumatology, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan.
Shunsuke
S
Noda
Masao
M
Ogura
Akiko
A
Tsutsumi
Tomohiro
T
Udagawa
Koichi
K
Kamei
Kentaro
K
Matsuoka
Hiroshi
H
Kitamura
Tatsuya
T
Atsumi
Shuichi
S
Ito
D016736:Antiphospholipid Syndrome / Q000150:complications* / Q000276:immunology / Q000503:physiopathology; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D001324:Autoantigens / Q000276:immunology; D002648:Child; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000276:immunology / Q000503:physiopathology; D008297:Male; D010718:Phosphatidylserines / Q000276:immunology; D011516:Prothrombin / Q000276:immunology; D057049:Thrombotic Microangiopathies / Q000209:etiology* / Q000276:immunology / Q000503:physiopathology
D001323:Autoantibodies; D001324:Autoantigens; D010718:Phosphatidylserines; D011516:Prothrombin