Immunoglobulin D myeloma--problems with diagnosing and staging (own experience and literature review)

Immunoglobulin D (IgD) myeloma is a rare disease accounting for about 2% of all myelomas. The distinctive features are the predominant occurrence in males and young patients, short survival time, uncertain appearance of M-component in serum electrophoresis, predominance of lambda light chains, frequent renal impairment, hypercalcemia and amyloidosis. The aim of the present study was to show diagnostic difficulties resulting from a variety of non-specific initial symptoms and laboratory findings as well as to compare the staging system proposed by Durie and Salmon with the new risk grouping by Shimamoto. Case histories of 7 patients were analyzed retrospectively. Five of them were diagnosed as IgD multiple myeloma (IgD MM), 1 as non-secretory IgD myeloma and 1 as solitary bone IgD plasmocytoma that evolved to an IgD MM. All patients were staged according to the Durie and Salmon classification and the new risk grouping by Shimamoto. We report diagnostic problems with IgD myeloma in our patients, with special emphasis on non-specific rheumatoidal and neurological symptoms in 1 case. There was a very good correlation of the Japanese classification with the severity of the disease and the risk of death. In conclusion, the initial symptoms of IgD myeloma can be very misleading. Wide differential diagnosis, including autoimmunological disorders of the connective tissue, is necessary. The new Japanese risk grouping seems to be of greater prognostic significance for IgD myeloma than the Durie and Salmon staging system.