Monoclonal Gammopathy Presenting as Recurrent Nephrotic Syndrome: Therapeutic Implications

Most forms of renal disease associated with monoclonal gammopathy result from deposition of monoclonal immunoglobulins or their subunits in different compartments of the kidney. Renal monoclonal immunoglobulin deposition disease (MIDD) is defined by linear deposits of monoclonal light-chain components in renal basement membranes, often producing a nodular sclerosing glomerulopathy. Clinical features of renal MIDD include proteinuria, with or without renal failure, and an association with dysproteinemias. Three types of renal MIDD have been reported, namely, light-chain deposition disease (LCDD), light- and heavy-chain deposition disease (LHCDD), and heavy-chain deposition disease (HCDD). Reports on LHCDD are rare. At present, follow-up data are limited on the management of renal monoclonal protein deposition disease. We present a case of monoclonal protein deposition in the kidney containing both heavy and light chains with unique characteristics that did not conform to any of the above previous established classes. Its follow-up revealed an unusual relapsing and remitting course in response to treatment.