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Background: Membranoproliferative glomerulonephritis (MPGN), a rare glomerulonephritis that causes nephrotic syndrome in children, is often difficult to treat. Typical immunofluorescence findings include strong C3 staining in a granular pattern along the glomerular capillary wall and negative IgA staining. IgA-dominant MPGN without hypocomplementemia has been reported. Herein, we report a rare case of MPGN with hypocomplementemia and predominant IgA subclass 2 deposits., Case Presentation: An 11-year-old girl showed proteinuria on a school urinalysis screening and presented with upper eyelid edema. The urinalysis showed elevated urinary protein levels and hematuria. Laboratory examinations revealed the following: serum albumin, 1.3 g/dL; serum creatinine, 0.54 mg/dL; and C3c, 67 mg/dL (normal range: 73-138 mg/dL). The physical and laboratory findings did not suggest autoimmune diseases. A renal biopsy was then performed. Specimen examination under a light microscope showed mesangial cell proliferation, increased mesangial matrix with lobulation, and some double contours of the glomerular basement membrane in almost all glomeruli, which are characteristic findings of MPGN. Immunofluorescent studies showed IgA deposits not only in the mesangial regions but also along the capillary walls, which were more strongly stained than C3. IgA subclass staining showed a stronger immunoreactivity for IgA2 than IgA1. Electron microscopic studies showed electron-dense deposits in the subendothelial, subepithelial, and paramesangial regions. Based on these findings, the patient was diagnosed with IgA-dominant MPGN. Accordingly, she was treated with three courses of methylprednisolone pulse therapy (MPT), followed by prednisolone, mizoribine, and lisinopril. Although hypocomplementemia improved after three courses of MPT, nephrotic-range proteinuria and hypoalbuminemia remained; therefore, two courses of MPT were additionally administered, and the immunosuppressant was changed from mizoribine to cyclosporine (CsA). Finally, the urinary protein level decreased, and a subsequent renal biopsy, two years later, showed improvement in the lesions., Conclusions: We report an atypical case of MPGN with IgA2 dominant deposits along the glomerular capillary wall and in the mesangial region. The case was refractory to standard therapy but sensitive to CsA, which resulted in remission. Our findings suggest that CsA may be useful as an immunosuppressant to treat refractory MPGN., (© 2022. The Author(s).)