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Background: Idiopathic membranous nephropathy is an uncommon cause of nephrotic syndrome in children and can present treatment challenges. The current treatment options of steroids and cyclophosphamide, cyclosporine, or mycophenolate require prolonged treatment durations and the associated side effects may result in nonadherence in children, especially in adolescents., Case-Diagnosis: We report two adolescent patients with idiopathic membranous nephropathy with nephrotic range proteinuria and elevated anti-phospholipase A2 receptor levels who did not achieve remission with steroids and were later treated with rituximab. Both patients received two doses of rituximab and responded with remission. In addition, anti-PLA2R antibody levels normalized and/or significantly improved., Conclusions: Rituximab seems to be a safe and effective treatment option in children with idiopathic membranous nephropathy due to anti-PLA2R. Further studies are needed to evaluate this effectiveness.

Immunoglobulin (Ig) M nephropathy is defined by electron-dense mesangial deposits and mesangial IgM visible by immunofluorescence (IF) without other histopathologic and immunofluorescent microscopic abnormalities. Certain patients have only immuno-positive (IgM+) IF. Children presenting with steroid-dependent or steroid-resistant nephrotic syndrome have a high prevalence of IgM+ IF with or without electron-dense deposits. We reviewed the clinical course of children with steroid-dependent or steroid-resistant nephrotic syndrome who underwent renal biopsy at Texas Children's Hospital from 1989 to 2006 to further characterize IgM+ IF in children with nephrotic syndrome. Of the 55 children with steroid-resistant or -dependent minimal change disease (MCD), 23 had IgM+ IF. Of these 23 children, 61% had microscopic hematuria at presentation, 48% (11/23) were steroid-dependent, and 48% (11/23) steroid-resistant (one underwent biopsy prior to steroid therapy). We compared the efficacy of adjuvant treatment with cyclophosphamide and cyclosporine: 18% initially treated with cyclophosphamide obtained remission, while 55% had no response; 83% obtained subsequent remission with cyclosporine. Of those initially treated with cyclosporine, 88% obtained complete or partial remission. IgM+ IF may be surrogate marker for the severity of MCD. Based on our results, children with MCD and IgM+ IF have a better response to cyclosporine than cyclophosphamide.