IgA Predominant Atypical Membranoproliferative Glomerulonephritis -A Clinicopathological Study-

Abstract

1. A new type of primary glomerulonephritis was experienced. Light microscopic and immuno fluorescence findings of renal biopsy were similar to those in cases of IgA-IgG nephritis, but exact observation revealed changes in glomerular capillary loops. Furthermore, electron microscopic findings were indistinguishable from those of membran.oproliferative glomerulonephritis (MPGN) type. 2. 17 cases demonstrating the pathological findings outlined above have been among 118 cases of primary glomerulonephritis. Among 17 cases, serial renal biopsy was performed in three cases. The Second renal biopsy findings of these three cases revealed evidently changes in glomerular capillary loops. 3. All 17 cases had persistent proteinuria and microscopic hematuria, with over 1g/day proteinuria and moderate microscopic hematuria in about 60% of the cases.Renal function was almost normal at first biopsies. Three cases, serial renal biopsy were performed, showed nephrotic syndrome, hypertension and moderate or severe impairment of renal function after a few years from the first renal biopsy. High IgA and IgM serum values were detected. The compiement was normal in 16 cases and low in one cases, leading to the presumption that the complement in the latter was activated by the classical pathway. 4. The clinical features and pathological findings of renal biopsy were such that these cases could not be diagnosed as either IgA-IgG nephritis or MPGN, i. e., these 17 cases lay somewhere between IgA-IgG nephritis and MPGN. Therefore, taking into consideration pathological findings regarding the glomerular capillary loops, this "new" primary glomerulonephritis was defined as IgA predominant atypical MPGN.