Antiphospholipid Antibodies and Associated Clinical Manifestations.

The Antiphospholipid Syndrome (APS) is defined by the association between antiphospholipid antibodies, i.e. anticardiolipin (aCL) and/or lupus anticoagulant (LA) antibodies, and one or more of the following clinical manifestations: arterial and venous thrombosis, recurrent abortions and thrombocytopenia (1). Among them, deep venous thromboses, pulmonary embolism and thrombosis of the cerebral arteries are the most frequent events, occurring in approximately 1/3 of the patients. Thrombosis of the placental vessels (2) is considered the cause of the obstetrical complications (recurrent spontaneous abortions, fetal deaths or fetal growth retardation) suffered by approximately 10% of the women with antiphospholipid antibodies (1), whereas a variable degree of thrombocytopenia is reported by about 20-25% of the patients (3). Less commonly, skin necrosis, livedo reticularis, hemolytic anemia, dementia or other neuropsychiatric events and the so-called "catastrophic" APS may also develop in the setting of APS (4, 5). Two types of APS have been described: the "Primary" APS, which occurs in the absence of an underlying disease (6), and the "Secondary" APS, which is related to Systemic Lupus Erythematosus (SLE), other autoimmune or neoplastic diseases or other pathological conditions (7). Noteworthy, a substantial amount of patients suffering from APS are young: 50% of the patients enrolled in the Italian Registry of Antiphospholipid Antibodies were aged less than 40 years (8).