[Minimal change nephrotic syndrome with predominant mesangial IgA deposits: clinicopathological study]

It has been reported that minimal change nephrotic syndrome (MCNS) shows no deposit of immunoglobulins or complement components in the glomeruli. We found 6 patients with IgA deposits in the glomeruli among 101 patients with MCNS, and examined the clinicopathological features of these cases. In all cases, light microscopy showed minor glomerular abnormalities. However, immunohistochemical study demonstrated marked IgA deposits in the glomerular mesangium. IgM was detected in 5 cases, IgG in 2, C3 in 2, and Clq in 1. On electron microscopy, small mesangial deposits were found in all cases and foot process effacement was partially demonstrated. There were no abnormalities in the glomerular basement membrane. The renal functions were within normal ranges in all 6 cases. In three cases, biopsies were performed within a month after the initiation of profuse proteinuria. In the other three cases, frequent relapses had been observed for 6 to 15 years before the biopsies. However, all patients ultimately revealed complete remission with corticosteroid treatment. Serum IgA levels were within normal range in examined 4 cases. Hematuria was negative in all of them. The clinical findings seem to be identical to MCNS rather than IgA nephropathy, and IgA deposits may have no pathogenetic significance, although the pattern of deposition looks quite similar to that of IgA nephropathy. These results indicate that the renal lesions in the 6 patients may belong to the subtype of MCNS, rather than IgA nephropathy.