IgM multiple myeloma with an extremely rare non-aggressive presentation: A case report.

In the present study, the case of a 41-year-old man with immunoglobulin (Ig)M multiple myeloma (MM) that presented with an unusually non-aggressive clinical course who has survived for >9 years to date, is presented. Initial diagnosis of symptomatic MM was established according to the International Myeloma Working Group consensus statement and guidelines. Due to the mild symptoms, no therapy was administered and the patient was closely followed up. Eight years after initial diagnosis, clinical, morphological and genetic progression occurred with the development of hypercalcemia, progressively deteriorating polyneuropathy, clonal expansion of plasma cells up to 50% of hematopoietic cells and demonstration of the typical t(11;14) translocation (Ig heavy chain locus rearrangement). Subsequently, 4 cycles of induction chemotherapy with velcade, cyclophosphamide and dexamethasone, were administered. At the time of writing, the patient remained alive in generally good health. To the best of our knowledge, with a survival time of >9 years, this case reports the longest survival time of an IgM MM patient to date, which contradicts previous evidence that suggests IgM MM exhibits an aggressive clinical course.