Renal thrombotic microangiopathy in systemic lupus erythematosus: clinical correlations and long-term renal survival

Background. Renal thrombotic microangiopathy (TMA) is an uncommon vascular complication of systemic lupus erythematosus (SLE). Its clinical symptoms and impact on renal survival remain unclear. Methods. Eight patients aged 25±6 years with biopsy-proven renal TMA and at least four ARA criteria for the diagnosis of SLE were retrospectively studied over a 7-year period. Results. All patients presented with renal failure (creatinine 3.3±2.1 mg/dl), six had proteinuria (2.5±1.3 g/day) with microscopic haematuria in four cases. Six patients had hypertension, which was severe in five cases. Renal histology disclosed arterial and/or arteriolar thrombosis with parietal thickening without angeitis (8 patients), glomerular microthrombi (3 patients), and vascular fibrin deposits (5/6 patients). In two cases, vascular lesions were associated with a mesangial or a proliferative glomerulonephritis. Thrombocytopenia was present in four patients with haemolytic microangiopathic anaemia in one case. Lupus anticoagulant (LA) was detected in five of eight patients, who also had anticardiolipin antibodies (3/7 patients) and/or were positive for VDRL (3/6 patients). Four patients with LA experienced arterial thrombosis and/or repeated spontaneous abortions. Treatment consisted of corticosteroids (8 patients), cytotoxic drugs (4 patients), plasma exchanges and/or intravenous immunoglobulins (4 patients) and antiplatelet and/or anticoagulant therapy (3 patients). Two patients recovered normal renal function and five had persistent renal insufficiency. One patient started haemodialysis on admission and died of sepsis 2 months later. Conclusions. TMA may also be the sole renal complication in SLE and is not usually associated with haemolytic microangiopathic anaemia. In our series renal survival was influenced by the extent and severity of vascular lesions. Despite a frequent association with antiphospholipid antibodies, pathophysiological mechanisms of renal TMA in SLE remain unknown. Renal histology is mandatory for the diagnosis and the prognostic evaluation of renal vasculopathy in SLE.