Kaseb Hatem, Annamaraju Pavan, Babiker Hani M.
Cleveland Clinic
Loma Linda University
Monoclonal gammopathy of undetermined significance (MGUS) is an asymptomatic premalignant plasma cell disorder that is characterized by the presence of serum M-protein less than 30 g/L or 3 g/dL, bone marrow (BM) clonal plasma cells less than 10%, absence of plasma cell myeloma (PCM) related end-organ damage (CRAB symptoms: hypercalcemia, renal insufficiency, anemia and, bone lesions) and absence of B-cell lymphoma or other disease known to produce an M-protein. MGUS is generally considered a preneoplastic disorder that does not always progress to overt malignancy. There are three distinct types of MGUS: 1. Non-IgM MGUS: Non-IgM MGUS (IgG, IgA, IgD) accounts for the majority of MGUS cases and is characterized by a monoclonal plasma cell. 2. IgM MGUS. 3. Light-chain MGUS. Non-IgM MGUS may progress to a malignant plasma cell neoplasm. IgM MGUS may develop into Waldenstrom macroglobulinemia, immunoglobulin light chain (AL) amyloidosis, or lymphoma. Light chain MGUS (LC-MGUS) is characterized by a monoclonal protein that lacks the immunoglobulin heavy chain component. LC-MGUS may show progression to idiopathic Bence Jones proteinuria, light chain PCM, AL amyloidosis, or light chain deposition disease. According to a population-based cohort study, the risk of progression to multiple myeloma in patients with light-chain MGUS is 0.3%.
意义未明的单克隆丙种球蛋白病（MGUS）是一种无症状的癌前浆细胞疾病，其特征为血清M蛋白低于30 g/L或3 g/dL、骨髓（BM）克隆性浆细胞低于10%、无浆细胞骨髓瘤（PCM）相关的终末器官损害（CRAB症状：高钙血症、肾功能不全、贫血和骨病变）以及无B细胞淋巴瘤或其他已知产生M蛋白的疾病。MGUS通常被认为是一种癌前疾病，并非总是会进展为明显的恶性肿瘤。MGUS有三种不同类型：1. 非IgM MGUS：非IgM MGUS（IgG、IgA、IgD）占MGUS病例的大多数，其特征为单克隆浆细胞。2. IgM MGUS。3. 轻链MGUS。非IgM MGUS可能进展为恶性浆细胞肿瘤。IgM MGUS可能发展为华氏巨球蛋白血症、免疫球蛋白轻链（AL）淀粉样变性或淋巴瘤。轻链MGUS（LC-MGUS）的特征是单克隆蛋白缺乏免疫球蛋白重链成分。LC-MGUS可能进展为特发性本-周蛋白尿、轻链PCM、AL淀粉样变性或轻链沉积病。根据一项基于人群的队列研究，轻链MGUS患者进展为多发性骨髓瘤的风险为0.3%。
