The clinical significance of mesangial IgM deposits and mesangial hypercellularity in minimal change nephrotic syndrome.

Some patients with minimal change nephrotic syndrome (MCNS) present on biopsy mesangial IgM deposits, which may be associated with mesangial hyperplasia. These patients have been considered as a possible subset with a different response to therapy as well as prognosis and designated as mesangial IgM nephropathy or mesangial proliferative glomerulonephritis. However, the clinical relevance of these biopsy findings has been questioned by others. We reviewed the clinical, biopsy, and follow-up data in 61 MCNS children, 33 with mesangial IgM and 28 free of immunoglobulins. There were no significant differences in response to therapy or prognosis between these two groups. The lack of IgM elution and heterologous in vitro C3 fixation in the biopsies of some MCNS cases with IgM mesangial deposits does not support the possibility that the deposited IgM plays an immunologic role.