CHILDHOOD IGM NEPHROPATHY - COMPARISON WITH MINIMAL CHANGE DISEASE

The distinctiveness of IgM nephropathy (IgMN) as a clinicopathologic e ntity is controversial. Twenty-seven children (16 males, 11 females) w ith IgMN as defined immunohistochemically by diffuse mesangial stainin g of glomeruli for IgM were compared to a group of 63 children (40 mal es, 23 females) with minimal change disease (MCD). While mesangial exp ansion was significantly greater in IgMN than in MCD (p = 0.0014), the re were no significant differences between the two groups with respect to the other biopsy factors. IgMN showed a significantly higher incid ence of hypertension at presentation. More than 90% of patients in bot h groups presented with the nephrotic syndrome which in most initially responded to prednisone. Frequently relapsing/steroid-dependent nephr otic syndrome was the most common indication for biopsy in both groups . Approximately 60% of patients from both groups received cytotoxic th erapy. Eight percent of IgMN and 7% of MCD patients failed to respond to therapy. Relapse rates and mean dose of prednisone at relapse were very similar in both groups prior to biopsy. Relapse rates diminished significantly after treatment in the postbiopsy interval, but mean dos e of prednisone at relapse did not change appreciably over time. None of the patients developed renal failure or hypertension in the follow- up period. At last visit 23% of IgMN and 27% of MCD had proteinuria. T he results indicate that IgMN and MCD are indistinguishable clinically in children who are biopsied for the nephrotic syndrome.