Retrospective Analysis of Five Cases of Proliferative Glomerulonephritis with Monoclonal IgG Deposition Regarding Their Clinical Course and Responses to Therapy

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Introduction: Background At present, limited knowledge is obtained regarding pathophysiology and clinical course of proliferative glomerulonephritis with monoclonal IgG deposition (PGNMID). It is rarely diagnosed by renal biopsy, and there is no established therapeutic strategy for this disease. We report clinical course and responses to the therapy of 5 cases diagnosed as PGNMID in our facility. Case Description: Method Five cases (3 males and 2 females, median age 62 years) with renal biopsies and diagnosed as PGNMID between January 2016 and December 2019 were retrospectively analyzed regarding the transition of eGFR and urine protein level by the treatment. Three of 5 cases were treated by steroid alone in combination with intravenous methyl Prednisolone (PSL) 500 mg/day for 3 days and oral PSL 30 mg/day. Remaining 2 cases were treated with intravenous methyl PSL and oral PSL followed by Cyclophosphamide intravenously (750 mg/day, twice) or orally (100 mg/day, daily) administration and Rituximab (500 mg/body, twice) administration. Results Light microscopic findings were MPGN type in all cases, and immunofluorescent staining showed 4 cases were IgG3-kappa and only 1 case was IgG3-lambda. Three cases in the first month of the treatment had partial remission (KDIGO diagnostic criteria, defined as a urinary protein level of < 0.3-3.5 g/day and a reduction of ≧ 50% from baseline), and all had partial remission at 6 months. Hematuria was observed at the start of treatment in three cases and disappeared in only one case by the treatment. And, the remarkable deterioration of renal function was not observed during the clinical coourse. However, two cases showed the increase of urine protein after about one year from mPSL administration, and IVCY and RTX were administered, but urine protein and hematuria were not decreased, and mPSL was administered again. In one case, the improvement of the urinary finding was scarce even after the increase in the administered steroid. Discussion: Conclusion Our results suggest that the treatment responsiveness to IVCY and RTX is poor, that steroids are more responsive to initial therapy, that disease activity increases with dose reduction (a steroid-dependent condition), and that treatment responsiveness to steroids may decrease after relapse.

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