Childhood IgM Nephropathy: Comparison with Minimal Change Disease

Abstract

The distinctiveness of IgM nephropathy (IgMN) as a clinicopathologic entity is controversial. Twenty-seven children (16 males, 11 females) with IgMN as defined immunohistochemically by diffuse mesangial staining of glomeruli for IgM were compared to a group of 63 children (40 males, 23 females) with minimal change disease (MCD). While mesangial expansion was significantly greater in IgMN than in MCD (p = 0.0014), there were no significant differences between the two groups with respect to the other biopsy factors. IgMN showed a significantly higher incidence of hypertension at presentation. More than 90% of patients in both groups presented with the nephrotic syndrome which in most initially responded to prednisone. Frequently relapsing/steroid-dependent nephrotic syndrome was the most common indication for biopsy in both groups. Approximately 60% of patients from both groups received cytotoxic therapy. 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 dose 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. The results indicate that IgMN and MCD are indistinguishable clinically in children who are biopsied for the nephrotic syndrome.

Clinical Profile &Treatment Outcome in Children with IgM Nephropathy

“…It follows from various studies that IgMN responds less well to steroids compared to typical minimal change disease (MCD), and favours the hypothesis that IgMN is distinct from MCD [2,6] . Other researchers have not found any significant differences in clinical, pathological or steroid response pattern among these diseases [1,15] . The data on the use and response rates of immunosuppressive agents in paediatric IgMN is quite inadequate [2,22] .…”

“…Glomeruli show diverse grade of mesangial hypercellularity or no changes by light microscopy [1] . However, recent edition of Heptinstall's pathology of the kidney (7 TH edition) defines IgMN as cases with bright staining (at least two positive out of three) and with demonstrable mesangial deposits on electron microscopy.…”

IgM nephropathy; can we still ignore it

“…The spectrum of morphological changes in glomerular pathology range from mild to moderate mesangial proliferation in majority of the cases involving about 70-75%, followed by FSGS in 15-20% and unremarkable morphology/ MCD in 5-10% biopsies (11,(20)(21)(22)(23)(24)(25). (figure 1a).…”

Update on IgM Nephropathy

“…Most of the studies have reported the prevalence of the disease as frequency or percentage of renal biopsies with a diagnosis of IgMN. The frequency of IgMN reported in literature has varied considerably from 2% to 18.5% (Al-Eisa et al, 1996;Cavalo et al, 1981;Kazi et al, 2010;Kopolovic et al, 1987;Lawler et al, 1980;Mampaso et al, 1981;Cavalo & Johnson, 1981;Chan et al, 2000;Donia et al, 2000;Hsu et al, 1984;Jungthirapanich et al, 1997;Kobayashi et al, 1982;Mubarak et al, 2011;Singhai et al, 2011;Tejani & Nicastri, 1983). The first two pioneering studies found frequencies of 2 and 6.1% respectively in their biopsy series (Cohen et al, 1978;Bhasin et al, 1978).…”

“…Variable degrees of fusion of foot processes commensurate with the degree of proteinuria have also been observed. The electron-dense deposits have typically been of low volume and low density, and in many cases, rather ill-defined (Al- Eisa et al, 1996;Hsu et al, 1984;Myllimaki et al, 2003). …”