When clonal plasma cells grow at anatomic sites distant from the bone marrow or grows contiguous from osseous lesions that break through the cortical bone, it is referred to as extramedullary multiple myeloma (EMD). EMD remains challenging from a therapeutic and biological perspective. The pathogenetic mechanisms are not completely understood and it is generally associated with high-risk cytogenetics which portends poor outcomes. There is a rising incidence of EMD in the era of novel agents, likely a reflection of longer OS, with no standard treatment approach. Patients benefit from aggressive chemotherapy-based approaches, but the OS and prognosis remains poor. RT has been used for palliative care. There is a need for large prospective trials for development of treatment approaches for treatment of EMD.

当克隆性浆细胞在远离骨髓的解剖部位生长或从突破皮质骨的骨病变邻近生长时，它被称为髓外多发性骨髓瘤（EMD）。从治疗和生物学角度来看，EMD 仍然具有挑战性。其发病机制尚不完全清楚，通常与预示不良结果的高风险细胞遗传学有关。在新药时代，EMD 的发病率不断上升，这可能反映了 OS 延长且没有标准治疗方法。患者受益于基于积极化疗的方法，但 OS 和预后仍然较差。 RT 已用于姑息治疗。需要进行大型前瞻性试验来开发 EMD 的治疗方法。