The occurrence of small-vessel occlusions (thrombotic microangiopathy) in association with anti-phospholipid antibodies (aPL) affecting, for example, the retinal vessels,¹ the nail fold,^2,3 the skin,⁴ or major intrabdominal organs such as the kidney, the liver or the bowel,⁵ although uncommon, is well documented. These occlusions have been described in the simple or classic antiphospholipid syndrome (APS), whether or not associated with systemic lupus erythematosus (SLE), or in the primary APS,⁶ but they do not in any way dominate the clinical picture in these conditions. However, with the description and definition of the catastrophic APS (also known as Asherson’s syndrome) in 1992^7,8 (a new subset of the APS, often fatal, with many distinguishing characteristics separating it from the simple APS),^9–11 there has been renewed interest in the thrombotic microangiopathies and their association with aPL. Although large-vessel occlusions do occur in catastrophic APS, they do not dominate the clinical picture, and their frequency is completely different from that encountered in the classic APS itself. Additionally, the catastrophic APS is frequently accompanied by a systemic inflammatory response syndrome (SIRS).

The term thrombotic microangiopathic haemolytic anaemia (TMHA) was originally introduced by Symmers¹² in 1952 to describe a clinical state with localised or diffuse microvascular thrombosis in association with haemolytic anaemia and fragmented red cells referred to as schistocytes. Indeed, the great haematologist John Dacie and his colleagues¹³ published a seminal paper on TMHA and related the condition to vascular damage some 10 years later. TMHA encompasses a spectrum of disorders including thrombotic thrombocytopenic purpura (TTP), haemolytic–uraemic syndrome (HUS), malignant hypertension, postpartum renal failure, pre-eclampsia and catastrophic APS. Recent articles still refer to the difficulty in distinguishing among these conditions …