ABSTRACT
An 51-year-old woman presented with microscopic hematuria without protenuria for long time. Laboratory studies demonstrated the presence of red blood cells in urine, a normal serum IgM level, the absence of antinuclear antibodies, and a normal complement level. Renal biopsy revealed that some glomeruli are enlarged with endocapillary cell proliferation and a few glomeruli exhibit prominent vascular pole of the tufts and segmental increase in mesangial cell and matrix. Immunofluorescence studies demonstrated segmental granular deposits for IgM. Electron microscopy showed well-preserved foot process associated with focal effacement. Biopsy findings were consistent with IgM nephropathy. We present this case to promote understanding of the pathogenesis of IgM nephropathy.