IgM nephropathy in adults: incidence and correlation with electron microscopic features.

ABSTRACT

IgM nephropathy is characterised on light microscopy (LM) by variable features of normal glomeruli to mesangial hypercellularity; and immunofluorescence (IF) deposits of LgM. Our aim was to study the incidence of IgM nephropathy in adults with primary glomerular disease, with correlation to electron microscopy (EM) features. All adults presenting with proteinuria glomerular hematuria underwent renal biopsy. We excluded patients with systemic diseases and post-infectious glomerulonephritis. All the specimens were evaluated by LM, IF and EM. Our series had 146 cases. Of the 42 cases diagnosed on LM as minimal change disease, mesangial deposition of IgM was present in 11 cases. In addition there were seven cases of mesangioproliferative glomerulonephritis with mesangial IgM deposition. Thus, there were a total of 18 cases of IgM nephropathy (12.3%). Only six of these 18 cases showed typical electron dense deposits in the mesangium on EM. We feel that IgM nephropathy is probably a separate pathological entity, comprising 12.3% of all adults with primary chronic glomerulopathy. Electron dense deposits are seen in only about a third of these cases.