F2 and cerebrovascular disorder: Although cerebrovascular diseases in SLE are often associated with antiphospholipid antibodies (aPL), such as lupus anticoagulant (LAC), anticardiolipin antibodies (aCL), and anti-β2 glycoprotein-I antibodies, reports of cases with sole positive anti-phosphatidylserine/prothrombin complex antibodies (aPS/PT) are also rare.