Research progresses in the pathogenesis of multiple myeloma with extramedullary disease

Multiple myeloma (MM) is a plasma cell malignant disease which is characterized by unlimited proliferation of monoclonal plasma cells and multiple infiltration of the bone marrow. Extramedullary myeloma (EMM) is found in some MM patients with extramedullary disease (EMD) at the initial diagnosis or during treatment. Particularly the hematogenous EMM has great heterogeneity and possesses poor prognosis in clinical applications. In general, the mechanism of EMM is closely related to cytogenetic abnormalities, the changes of the adhesion molecules, chemokine receptors, abnormal cytokine expression and exosomes etc. in bone marrow microenvironment. The authors focuses on the pathogenesis of EMM, in order to explore the causes of EMM heterogeneity. Key words: Multiple myeloma; Neoplasm metastasis; Plasmacytoma; Extramedullary myeloma; Hematogenous metastasis; Pathogenesis