Clinical improvement of acquired partial lipodystrophy in an adolescent with C3 glomerulopathy treated with pegcetacoplan.

C3 glomerulopathy and acquired partial lipodystrophy (APL) are rare disorders associated with dysregulation of the alternative complement pathway and occasionally coexist. We report a 14-year-old girl who developed nephritic-nephrotic syndrome due to C3 glomerulonephritis concomitant with APL. Despite treatment with mycophenolate mofetil and tacrolimus, kidney function deteriorated, proteinuria increased, and she developed marked faciotruncal lipoatrophy with a 10-kg weight loss. Pegcetacoplan, a C3/C3b inhibitor, was initiated. Five weeks later, serum C3 levels were normal. Creatinine clearance subsequently improved from 25 to 133 mL/min, while proteinuria progressively declined from 3.2 to 0.15 g/g. Within 40 weeks, the patient recovered her usual body weight with marked clinical improvement in subcutaneous fat distribution. This observation suggests that pegcetacoplan may represent a novel therapeutic option for APL.