[The Pathogenesis and Treatment Progress of Extramedullary Multiple Myeloma --Review]

Extramedullary disease (EMD) is an independent prognostic factor for multiple myeloma (MM). Compared with MM without EMD, MM with EMD has different genetic characteristics, with a higher incidence of high-risk chromosomal abnormalities, more complex genomic profile, and immunophenotypic features related to adhesion molecule and chemokine expression. The mutual regulation between myeloma cells and tumor microenvironment, including changes in immune environment, deposition of extracellular matrix, abnormal expression of adhesion molecules, and autocrine secretion of myeloma cells, is involved in the extramedullary migration of myeloma cells. Various immune-targeted therapies have improved the prognosis of extramedullary MM (EMM). This article reviews the genetic characteristics of EMM, important role of tumor microenvironment, and progress of treatment.