Two Faces of the Same Coin: A Case Report of Antiphospholipid Syndrome Nephropathy

Antiphospholipid syndrome (APS) is an autoimmune disease which can be primary or secondary to other autoimmune conditions and is defined by the occurrence of arterial or venous thrombosis, or pregnancy morbidity associated with persistently positive antiphospholipid antibodies (aPLA). The kidney may be affected by thrombosis at any level of its vasculature. When small vessels are involved, this results in thrombotic microangiopathy (TMA), which can manifest as either acute vaso-occlusive or chronic vascular lesions in glomeruli, arterioles and interlobular arteries. We report the case of 26-year-old man, with a previous medical history suggestive of APS, who was found to have a small elevation in serum creatinine. A kidney biopsy was performed and revealed features of chronic TMA. Anticoagulation was begun and kidney function remained stable. However, one year later, upon suspension of anticoagulation, the patient developed acute kidney injury and a second kidney biopsy showed acute TMA. This case describes different manifestations of antiphospholipid syndrome nephropathy (APSN) and highlights the importance of anticoagulation for thrombosis prevention. LEARNING POINTS: Antiphospholipid syndrome nephropathy (APSN) can be a difficult diagnosis because (i) antiphospholipid syndrome (APS) is not always clinically evident and (ii) APSN can manifest as subtle histological findings of chronic vascular damage which may be overlooked on a kidney biopsy. Acute kidney injury due to acute thrombotic microangiopathy (TMA) may develop in a patient with chronic TMA, often after a precipitating event. In the case reported here, the most likely trigger was the suspension of anticoagulation after a surgical emergency. Long-term anticoagulation is the mainstay of treatment for both APS and APSN; discontinuing anticoagulation increases the risk of thrombosis and has to be carefully weighed against the risk of serious haemorrhage.