Abstract
BACKGROUND: Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple systems with various clinical manifestations. Renal involvement is common, but intracardiac thrombus is rarely reported as a complication of antiphospholipid syndrome (APS, also known as anticardiolipin syndrome). Anticoagulant therapy is the first-line treatment, and surgery is performed in severe cases. We report a case to improve clinicians' understanding of disease diagnosis. CASE PRESENTATION: An 8-year-old girl was admitted to our hospital because of left costal pain, hematuria and fever. She had obvious edema occult blood 3+, urinary protein 3.2 g/24 h, albumin 17.6 g/L, and total cholesterol 7.21 mmol/L, consistent with a diagnosis of nephrotic syndrome. We continued to track the etiology of nephrotic syndrome and performed a renal biopsy, showing dsDNA 1:10 positivity, low C3, low platelets and hemoglobin, anticardiolipin IgM 12 U/ml, anti-β2-glycoprotein I (β2GPI) 223 U/ml; renal pathology suggested lupus nephritis (LN), and the patient was ultimately diagnosed with SLE, secondary APS and LN. The patient was treated with hormones and immunosuppressants. Sixteen weeks later, her urinary protein was 1+, and the quantity of urine protein was less than 0.5 g/d. Echocardiography showed that the mass in the right atrium was thrombotic. Heparin anticoagulant therapy was effective. CONCLUSION: SLE can involve multiple systems and various complications. Thrombus in the right atrium is a rare complication of APS. Early diagnosis and treatment are key to improving the prognosis of children.