A case of IgD myeloma with extraosseous spread to the gingiva.

A case of IgD myeloma at first diagnosed as Bence Jones type is reported. Multiple myeloma was diagnosed in the patient, a 39-year-old man with a tumor of the gingiva, because of the presence of multiple bone lesions with plasma cell proliferation and profuse urinary excretion of Bence Jones protein (lambda-type). An increase of serum IgD level (770 mg/dL) and a decrease in other classes of immunoglobulins were indicated by quantitative analysis; however, no apparent M-component was indicated by conventional electrophoresis on a cellulose acetate membrane. Microscopic examination of the specimen showed numerous atypical plasma cells. The disease profile of IgD myeloma, as well as the reasons IgD myeloma may be easily mistaken for Bence Jones type myeloma, is discussed.