Myeloma with two monoclonal IgG and IgD in serum: a case report.

We report the case of a woman, who initially presented with an IgG kappa-type monoclonal gammopathy. An IgD-secreting myeloma was diagnosed 2 years later. The patient died of severe renal failure and infection. The discrepancy between the immunoglobulin concentration estimated from the electrophoresis pattern and the immunonephelometric measurement of IgG, IgA and IgM led us to investigate the existence of an IgD myeloma. It was of the IgD kappa type and had electrophoretic characteristics identical to the initial monoclonal IgG. A common clonal origin for these two immunoglobulins is discussed.