Primary versus secondary antiphospholipid syndrome: is this lupus or not?

Antiphospholipid syndrome is a hypercoaguable state characterized by recurrent venous and/or arterial thrombosis and/or pregnancy complications of fetal loss, pre-eclampsia, or eclampsia in the presence of antiphospholipid antibodies. It was first described in the setting of systemic lupus erythematosus and subsequently recognized to also exist as an independent condition and in conjunction with a variety of other autoimmune, infectious, and malignant illnesses. These diseases have been called primary antiphospholipid syndrome and secondary antiphospholipid syndrome. However, the two conditions can have significant overlapping features. This paper reviews the similarities and the differences between the two conditions.