Evolocumab in the treatment of refractory chylothorax induced by systemic lupus erythematosus complicated with hyperlipidemia: a case report and literature review

Recurrent chylothorax induced by thoracic duct injury in patients complicated with mixed hyperlipidemia secondary to systemic lupus erythematosus (SLE) is rarely encountered in clinical practice. A 55-year-old female patient diagnosed with SLE, whose predominant clinical manifestation was refractory pleural effusion, is reported in this paper. Combined immunosuppressive therapy consisting of glucocorticoids, cyclophosphamide (CYP) and hydroxychloroquine (HCQ) was administered to the patient for 8 months. Although the disease activity of SLE was effectively controlled, intermittent albumin infusion, closed thoracic drainage and intensive lipid-lowering therapy were supplemented during the treatment period, yet recurrent pleural effusions were still detected. At this stage, low-density lipoprotein (LDL) was reduced below the target level, while total cholesterol (TC) and triglyceride (TG) were persistently maintained at elevated levels. Chylous pleural effusion was confirmed by pleural fluid examinations. Thoracic duct injury was presumed to be triggered by two combined factors including active SLE and hyperlipidemia. Intensive lipid-lowering treatment was therefore required on the basis of effective control of SLE activity. Evolocumab, a representative drug of proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i), was selected to further strengthen blood lipid regulation. Serum lipid levels were restored to normal ranges during the treatment course. Pleural effusions were effectively controlled without recurrence, and serum albumin levels were gradually normalized. Positive therapeutic effects of PCSK9 inhibitors on patients suffering from refractory chylothorax caused by SLE combined with mixed hyperlipidemia are indicated by this case.