IgM myeloma is a rare disease, accounting for approximately 0.5% of multiple myelomas (MM). Here we report four cases of IgM multiple myeloma. Two were diagnosed in advanced clinical stages with multiple osteolytic lesions, leading to hypercalcemia in one patient. Bone marrow morphology showed a variable degree of infiltration with mainly mature plasma cells. An immunophenotypic analysis performed in one case showed expression of CD38 and monoclonal cytoplasmatic immunoglobulin. Interphase fluorescence in situ hybridization performed in one case did not reveal any aneuploidies or deletions of the retinoblastoma, P16, or P53 tumor suppressor genes. While one patient with a smoldering IgM myeloma did not need specific therapy, the others received cytotoxic treatment based on standard chemotherapy for MM. The outcomes were one stable disease, one sustained complete remission, and one progressive disease. All four patients were alive 1 year after diagnosis. One died due to progressive disease after 31 months. We conclude that IgM myeloma shares clinical and histological features with other MM rather than with Waldenström's macroglobulinemia, which is most commonly diagnosed in cases with IgM monoclonal gammopathy. Since MM and Waldenström's macroglobulinemia differ in prognosis and treatment strategies, the two disease entities should be distinguished based on clinical criteria, bone marrow morphology, and immunophenotypic analysis.
"The cells in IgM myeloma appear to be arrested at a point of maturation between that of WM and MM. Preliminary data indicate that a pattern of osteoclast-activating factor and osteoprotegerin expression similar to that observed in classic MM is present in IgM myeloma [5,9-12]. Even though the cells of origin in WM and MM are mature and heavily mutated cells, they differ in IgH gene rearrangements. "
[Show abstract][Hide abstract] ABSTRACT: IgM multiple myeloma is rare disorder, which has clinical, laboratory and radiological manifestations that are consistent with both multiple myeloma and Waldenstrom's macroglobulinaemia.
An 83 years Welsh lady presented with clinical and radiological features consistent with spinal cord compression. Further investigations confirmed the diagnosis of IgM multiple myeloma. Following localized radiotherapy and five courses of melphalan and prednisolone, the patient achieved partial remission of her myeloma. Later on, the patient had disease progression in the form of rising serum IgM level and the development of multiple plasmacytomas. She was treated with thalidomide, cyclophosphamide, dexamethasone and radiotherapy, which resulted in the control of her disease for one year. To our knowledge, this is the second case of IgM myeloma presenting with a plasmacytoma and the first case of IgM myeloma presenting with cord compression caused by plasmacytomas.
Unlike other types of multiple myeloma IgM myeloma is rarely complicated by plasmacytomas. However, spinal cord compression caused by plasmacytomas in this type of myeloma is extremely rare. Nevertheless, the same lines of management, e.g. cytotoxic chemotherapy and local radiotherapy that are applied to other types of myeloma can be successfully utilized.
"However, there may be a discrepancy in the production of the heavy and light chains leading to an imbalance, with an excess of free light chains – K or L – excreted in the urine (BJP). Occasionally, the transformed PCs do not secrete any Ig, a condition called non-secretory MM (Östenborg et al., 1996a; Dierlamm et al., 2002; Avet-Loiseau et al., 2003b; International Myeloma Working Group, 2003;). "
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