The lupus anticoagluant and the anticardiolipin antibody were characterized as acquired antibodies. Clinical and serologic criteria for the classification of APS have been proposed on the basis of a study of 667 SLE patients:
Classification of Antiphospholipid Syndrome
- Vascular thrombosis (one or more clinical episodes of arterial, venous, or small vessel thrombosis).
- Pregnancy morbidity (one or more unexplained deaths of a morphologically normal fetus at or beyond the 10th week of gestation / one or more premature births at or before the 34th week of gestation / three or more unexplained consecutive spontaneous abortion before the 10th week of gestation).
- Anticardiolipin antibodies (IgG and/or IgM)
- Lupus anticoagulant
Definite antiphospholipid antibody syndrome is considered to be present if at least 1 of the clinical criteria and 1 of the laboratory criteria are met.
Multiple faces of the antiphospholipid syndrome
(Asherson RA, Cervera R (2003) Autoim Rev 2: 140-151)
Single vessel involvement or multiple vascular occlusions may give rise to a wide variety of presentations.
Deep vein thrombosis, sometimes accompanied by pulmonary embolism, is the most frequently reported manifestation in this syndrome (about 39 %).
Cerebrovascular accidents - either stroke (20 %) or transient ischemic attacks (11 %) - are the most common arterial thrombotic manifestations.
Early fetal loss (35 %), late fetal loss (17 %), premature birth (11 %), and pre-eclampsia (10 %) ar the most frequent fetal and obstetric manifestations.
Several other clinical features are relatively common in these patients, i.e. thrombocytopenia (30 %), livedo reticularis (24 %), heart valve lesions (12 %), hemolytic anemia (10 %), epilepsy (7 %), myocardial infarction (6 %), leg ulcers (6 %), and amaurosis fugax (5 %).
However, a large variety of clinical manifestations have been occasionally described in patients with APS, with prevalences lower than 5 %. Virtually any organ, system or tissue of the body can be affected.
APS can be manifested in such diverse conditions such as chorea, intracardiac thrombus, ARDS, Addison's disease, Budd-Chiari syndrome, AVN of bone or HELLP syndrome, just to name a few.