RESUMO
Membranoproliferative glomerulonephritis (MPGN) secondary to a monoclonal gammopathy is a rare glomerular disease and is defined as a monoclonal gammopathy of renal significance. The disease is characterized by glomerular monotypic immunoglobulin deposits and specific changes on light microscopy and electron microscopy. Immunochemistry is required to establish monoclonality, and electron microscopy helps to characterize the deposits ultrastructurally. Investigation for the underlying monoclonal protein should be done. We report a case of MPGN secondary to monoclonal gammopathy of renal significance that responded to treatment of the underlying clone with chemotherapy, resulting in improvement in renal function. Patients with MPGN and immunoglobulin deposition should be evaluated for a monoclonal protein to guide the management strategy.