Antiphospholipid antibodies in asymptomatic pediatric patients

BACKGROUND: Findings of prolonged activated partial thromboplastin time (APTT) and lupus anticoagulant are rare in asymptomatic children and are often preceded by certain types of surgery. Clinical behaviour is usually favorable. PATIENTS AND METHODS: We assessed the biological and clinical features of antiphospholipid antibodies found in 13 children diagnosed between January 1996 and September 2000 (mean age at diagnosis: 5 years). The patients were prospectively followed-up for a median of 16 months (range: 15-60). The diagnosis of lupus anticoagulant was based on the guidelines of the International Society of Thrombosis and Hematosis and included coagulation-based assays as well as enzyme-linked immunosorbent assay for anticardiolipin and anti-beta 2 glycoprotein I. RESULTS: In all patients lupus anticoagulant was detected after investigation of prolonged APTT prior to surgery (adenoidectomy in eight patients, orchidopexy in one and eye surgery in one). The antibody was associated with infectious mononucleosis in one patient and was detected during routine laboratory investigations in two. All antibodies were primary and 53.6% of events were transient. In all patients lupus anticoagulant IgG and anti-beta 2 glycoprotein I were negative. Slightly reduced factor XII:C plasma concentrations (mean: 38.2 UI/dl) were found in 30.7% of the patients. No clinical manifestations of antiphospholipid symptoms were associated with the diagnosis of antiphospholipid antibodies and none of the patients experienced bleeding after surgery. CONCLUSIONS: Primary antiphospholipid antibodies were infrequent in asymptomatic pediatric patients and were typically associated with certain types of surgery (adenoidectomy, tonsillectomy) or viral infections. They were usually transient and clinically irrelevant. These antibodies may be associated with slightly reduced plasma concentrations of factor XII and consequently a differential diagnosis with a mild factor XII deficiency should be considered.