Multiple myeloma (MM) derives from the clonal proliferation of plasma cells, primarily residing in the bone marrow. However, MM cells can disseminate systemically, leading to osseous or soft tissue extramedullary disease (EMM) or plasma cell leukemia (PCL). The presence of EMM or PCL has historically been linked to poor prognosis and aggressive features. In this study, we analyzed 201 patients with EMM treated at our institution between January 1, 2010, and November 30, 2023. Among these patients, 25 had primary PCL, 19 had secondary PCL, 89 were diagnosed with EMM at the time of MM diagnosis, 29 developed EMM after therapy, and 39 had solitary plasmacytoma (SP), with 20 progressing into MM. Patients with EMM at the time of MM diagnosis or SP progressing to MM exhibited a median overall survival (OS) comparable to those with MM alone (7.5 years or not reached). However, the presence of EMM was associated with worse prognosis in specific groups: primary PCL (median OS: 26 months), secondary PCL (median OS: 1.6 months), and secondary EMM (median OS: 16 months). Additional prognostic features included high R-ISS (Revised International Staging System), chromosomal abnormalities (1q+, 17p deletion, and 13q deletion), and elevated lactate dehydrogenase values at presentation. While the site of EMM did not correlate with inferior outcomes, osseous SP increased the risk of progression to overt MM. In conclusion, the presence of EMM confers variable prognosis, emphasizing the need for more effective therapeutic strategies, particularly for patients with PCL or those developing EMM later during treatment.

多发性骨髓瘤（MM）源自骨髓中浆细胞的克隆增殖。然而，MM 细胞可以系统性扩散，导致骨骼或软组织外胚层疾病（EMM）或浆细胞白血病（PCL）。历史上，存在 EMM 或 PCL 通常与预后不良和进展迅速相关。在这项研究中，我们分析了2010年1月1日至2023年11月30日期间在本机构接受治疗的201名 EMM 患者的数据。这些患者中有25人患有原发性 PCL，19人患有继发性 PCL，89人在 MM 诊断时被诊断为 EMM，29人在治疗后出现 EMM，39人患有孤立性浆细胞瘤（SP），其中20例进展为 MM。在 MM 初诊时伴有 EMM 或 SP 进展为 MM 的患者表现出与仅患 MM 患者相似的中位总生存期（OS）（7.5年或未达到）。然而，EMM 存在与特定群体预后较差相关：原发性 PCL（中位 OS：26个月），继发性 PCL（中位 OS：1.6个月），以及继发性 EMM（中位 OS：16个月）。其他预后特征包括高 R-ISS（修订后的国际分期系统）、染色体异常（1q+、17p 缺失和 13q 缺失）和初诊时乳酸脱氢酶值升高。虽然 EMM 的部位与较差结果无相关性，但骨骼 SP 增加了进展为明确 MM 的风险。总之，EMM 的存在赋予不同的预后，强调需要更有效的治疗策略，特别是对于 PCL 患者或在治疗过程中后期出现 EMM 的患者。