Extramedullary Disease in Multiple Myeloma

Purpose of Review Extramedullary disease (EMD) is a rare but recognized manifestation of multiple myeloma (MM), characterized by involvement of several organs including skin, liver, lymphatic system, pleura, and central nervous system. The incidence is about 3–5% in newly diagnosed MM patients, but has been reported in up to 20% patients in the relapsed MM setting. Recent Findings Presence of EMD has been associated with more aggressive phenotype of MM, elevated serum lactate dehydrogenase (LDH) enzyme, and high-risk cytogenetics [deletion 17p, translocation (4;14), translocation (14;16)]. There are several hypotheses of how EMD occurs, including factors leading to bone marrow emancipation and hematogenous spread. The treatment schema usually follows that of high-risk MM. Summary The current review summarizes the disease characterization data, along with available data on clinical activity of available anti-MM agents for this entity.