目的 探讨伴有淋巴间质的微结节型胸腺瘤(micronodular thymoma with lymphoid stroma, MNT)患者的临床、病理特点。方法 对2020年1月至2023年7月在上海交通大学医学院附属瑞金医院胸外科手术切除，并经病理确诊的连续的5例MNT患者的临床症状、病理特征、免疫表型、临床治疗及预后进行回顾性分析，并复习相关文献。结果 5例MNT患者中男性3例，女性2例，年龄为55~68岁。4例位于前纵隔，1例位于上纵隔，为胸部CT偶然发现。肿瘤直径1.3~4.5 cm，3例包膜完整，边界清楚，切面呈实性，灰白色，质地细腻；2例呈囊实性，2例包膜侵犯。显微镜下均有MNT独特的组织学表现：肿瘤主要由上皮性结节及淋巴细胞组成；上皮细胞呈短梭形或卵圆形，异型性小，核仁不清楚，核分裂象罕见，无坏死；上皮性结节之间被淋巴细胞间隔，可见淋巴滤泡形成。免疫组化检测显示，5例肿瘤细胞全都表达AE1/AE3、CK19、P63、Bcl-2；1例囊性区囊壁腔缘衬覆细胞表达EMA，不表达P63、Bcl-2；5例淋巴细胞表达CD20、CD3、CD5、TdT(少量+)，滤泡生发中心表达CD10，结节内朗格汉斯细胞表达Langerin、S100、CD1α。5例患者中3例行EBER原位杂交检测，结果显示，上皮细胞及淋巴细胞均阴性。5例患者手术切除肿瘤后，随访7~39个月，均未见肿瘤复发。复习2019年至2023年间Pubmed、Medline、中国知网、万方数据库新报道的以及文献中总结的既往1999年至2018年间的MNT病例，共206例MNT患者，中老年人（＞45岁）195例，青年人（18~45岁）9例，儿童（＜18岁）2例，发病部位以纵隔为主，也可见于颈部，发病人群无性别差异，多为体检时发现，切面以囊性稍多见，术后仅1例复发。结论 MNT罕见，好发于中老年人纵隔，手术切除后预后良好。MNT病理特征为上皮性结节散在分布于丰富的淋巴间质中，可见淋巴滤泡形成，结节内散在朗格汉斯细胞，可伴囊性变，结合发生部位、组织病理学特点及免疫组化标志物可以确诊，但仍需与其他病变鉴别。

Objective To investigate the clinicopathological characteristics of micronodular thymoma with lymphoid stroma (MNT). Methods A retrospective analysis was conducted on five MNT patients who underwent surgical resection at the Department of Thoracic Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine between January 2020 and July 2023. Their clinical symptoms, pathological features, immunophenotypes, clinical treatments, and prognosis were evaluated, along with a literature review. Results Among the five MNT patients, three were male and two were female, aged 55 to 68 years. Four cases had tumors located in the anterior mediastinum and one in the superior mediastinum, all incidentally discovered by chest CT. The tumor diameters ranged from 1.3 to 4.5 cm. Three cases had intact capsules with clear boundaries and solid, gray-white, and fine-textured cut surfaces. Two cases exhibited cystic-solid morphology, while two cases showed capsule invasion. Microscopically, all cases demonstrated unique histological features of MNT: tumor primarily consisted of epithelial nodules and lymphocytes. The epithelial cells showed short spindle or oval shapes, with mild atypia, indistinct nucleoli, rare mitotic figures, and no necrosis. Lymphocytes were interspersed between the nodules, accompanied by visible lymphoid follicle formation. Immunohistochemical staining showed that tumor cells in all five cases were positive for AE1/AE3, CK19, P63, and Bcl-2. In one case, epithelial lining cells of the cystic area exhibited EMA expression but were negative for P63 and Bcl-2. Lymphocytes in all five cases showed expression of CD20, CD3, CD5, and TdT (focal +), follicular germinal centers were positive for CD10, and Langerhans cells within the nodules expressed Langerin, S100, and CD1α. EBER in situ hybridization was performed in three cases, all of which were negative for both epithelial and lymphoid cells. During a follow-up period ranging from 7 to 39 months after surgical resection, no recurrence was observed. A literature review of newly reported MNT cases from 2019 to 2023 in PubMed, Medline, China National Know-ledge Infrastructure, and Wanfang databases, along with summarized cases from 1999 to 2018 in the literature was conducted. A total of 206 MNT cases were identified. Among them, 195 were elderly patients (>45 years), 9 were young adults (18-45 years old), and 2 were children (<18 years old). The majority had tumors located in the mediastinum, although some were found in the neck. No significant gender preference was observed. Most cases were incidentally detected during physical examinations. Cystic features were more common on cut surface. Only one case experienced recurrence after surgery. Conclusion MNT is a rare tumor predominantly occurring in the mediastinum of middle-aged and elderly individuals. It demonstrates favorable prognosis after surgical resection. The pathological features of MNT include scattered epithelial nodu-les within a rich lymphoid stroma, with visible lymphoid follicle formation. The nodules contain scattered Langerhans cells and may exhibit cystic changes. A definitive diagnosis can be made based on the tumor’s location, histopathological features, and immunohistochemical markers. However, it still requires differentiation from other lesions.