We report a severe hemorrhagic disorder in two pediatric patients with lupus anticoagulant (LA) associated to acquired factor II (prothrombin) deficiency. In both patients, hemorrhagic symptoms resolved after corticosteroid therapy. Serial coagulation studies showed that Staclot LA assay was more sensitive than DVVconfirm and Staclot PNP tests to confirm the presence of LA when associated with severe factor II deficiency. Both patients had non-neutralizing anti-prothrombin antibodies and their titers inversely correlated with factor II activity (r = -1.0, P < 0.0001). Associated findings in these patients included positive immunologic tests for systemic lupus erythematosus, a positive anti-cardiolipin antibody, and anti-beta(2) GPI antibodies in one case. Our findings point out the difficulty in diagnosing LA associated with acquired factor II deficiency and suggest that, in confirmation of its phospholipid dependency, the inclusion of a source of normal human plasma in the test sequence to correct for any factor deficiency and a confirmatory step utilizing hexagonal (II) phase phospholipids may be crucial to the diagnosis of LA in some patients with LA-hypoprothrombinemia syndrome.
