The pathogenesis of multiple myeloma

The pathogenesis of multiple myeloma (MM) is complex but appears to follow a two-step model of progression. First, monoclonal gammopathy of undetermined significance (MGUS) develops as a result of genetic changes, some of which are thought to be the product of repeated exposure to the mutagenetic effect of activation-induced cytidine deaminase (AID). Interaction of plasma cells with the bone marrow microenvironment and a single or a small number of additional (secondary) genetic events then results in progression to MM. End-organ damage is related to the infiltration of plasma cells into the bone or other organs or to kidney damage from excess light chains.