Primary Antiphospholipid Syndrome in children: A Single Institution Experience

OBJETIVE: This study was to assess the clinical and immunological features, of children with primary antiphospholipid syndrome and highlight several unique clinical characteristics referred to as non-criteria manifestations of the disease. MATERIALS AND METHODS: We retrospectively analyzed the medical records of prospectively collected data of 16 patients with vascular thrombosis that met the Sapporo and updated Sydney criteria for definite antiphospholipid syndrome, and of six patients with non-thrombotic manifestations, with follow-up at the hematology department of the Instituto Nacional de Pediatría, México, between January 2010 and December 2016. RESULTS: Mean age was 8.9 years for patients with vascular thrombosis, and 15 years for patients with non-criteria manifestations. There was an equal female/male ratio in patients with vascular thrombosis and a high female predominance 5:1 in patients without thrombotic manifestations. Arterial thrombosis was the presenting event in nine patients (56.25%) and venous thrombosis in seven patients (43.75 %). One of the patients (11.1%) with arterial thrombosis had a recurrence, and four (57.1%) of the seven with venous thrombosis had one or more recurrences. IgG, IgM (or both) anticardiolipin and anti-b2glycoprotein I antibodies were detected in 44% and 66.6% respectively of the patients with arterial thrombosis and in 28.6% and 50% respectively of the patients with venous thrombosis. Lupus anticoagulant was present in 55.5% of the patients with arterial thrombosis and in 100% with venous thrombosis. Three patients with vascular thrombosis, two of them with arterial and one with venous thrombosis, expressed a high-risk antiphospholipid antibody profile (triple positivity) at presentation. Despite long-term anticoagulation treatment with vitamin K antagonists, there was a high rate of recurrent thrombosis after a first event in patients with DVT. Non-thrombotic hematologic manifestations showed an adequate response to corticosteroids or IgG. CONCLUSIONS: The clinical spectrum of antiphospholipid syndrome in children has unique features not limited to vascular thrombosis, that cannot be explained only by a pro-thrombotic state, but also by the contribution of inflammatory mechanisms. Since currently there are no universally validated diagnostic criteria for pediatric antiphospholipid syndrome, some differences in important features between childhood and adult antiphospholipid syndrome, must be adapted for the diagnostic classification criteria in children.