Objective: To investigate the clinicopathologic features of micronodular thymoma with lymphoid stroma(MNT). Methods: Five cases of MNT diagnosed from January 2007 to December 2016 in Henan Provincial People's Hospital were collected.Hematoxylin-Eosin staining and immunohistochemistry were used to evaluate the histological and immunophenotypic characteristics in 5 MNT cases. Epstein-Barr virus (EBV) status was detected by in situ hybridization for EBV-encoded small RNA (EBER). Polymerase chain reaction was used to detect the rearrangement of immunoglobulin genes. Results: Five cases were MNT, including 3 male and 2 female patients, mean aged 59 years (from 43 to 63 years). All patients had ananterior mediastinal mass, with no myasthenia gravis and autoimmune diseases, and underwent surgical resection.Half to ten years follow-up showed no recurrence.Grossly, the tumors were solid in 4 cases, and cystic and solid in 1 case; the border was clear. Histologically, the tumors presented as a distribution of micronodules separated by abundant lymphoid stroma with prominent germinal centers. The nodules were composed of neoplastic spindle, oval cells containing bland, oval nuclei.Immunohistochemical study showed strong positivity of the tumor cells for CKpan, CK19, CK5/6 and p63. Stains for EMA, CD117, calretinin, TTF1 were negative in the tumor cells.Scattered CD3, CD1a, and TdT positive immature T lymphocytes were noted in and around tumor nodules. Many lymphocytes in the stroma, including germinal centers, were positive for CD20.The bcl-2 was also detected in lymphocytes in the stroma, mantle and marginal zone of lymphoid follicles, and in part of tumor cells. Tumor cells and lymphocytes were negative for EBER. Immunoglobulin genes rearrangement analysis showed that B lymphocytes were polyclonal. Conclusions: MNT is a rare thymoma, which occurs in the elderly and has no obvious symptom. After complete resection, the prognosis is very good. The diagnosis should be based on a combination of clinicopathologic features, and other types of thymoma should be excluded.
目的： 探讨伴淋巴样间质的微结节型胸腺瘤(MNT)临床病理学特点。 方法： 收集河南省人民医院2007年1月至2016年12月诊断的5例MNT的患者资料，采用HE染色、免疫组织化学EnVision法染色观察组织形态特征及免疫表型情况，EB病毒编码小RNA(EBER)原位杂交检测EB病毒感染情况，PCR法检测免疫球蛋白(Ig)基因重排，并对患者进行随访。 结果： 5例MNT患者平均年龄59(43～63)岁，男性3例，女性2例，均为前纵隔占位性病变，均无重症肌无力、自身免疫疾病，均行手术切除，术后随访0.5～10.0年，均未见复发。肿物4例实性，1例囊实性，边界较清，局部有包膜。上皮样瘤细胞呈微结节状分布，形态温和，间质见丰富的淋巴细胞及淋巴滤泡。瘤细胞广谱细胞角蛋白(CK)、CK19、CK5/6、p63阳性，CD117、钙网膜蛋白、甲状腺转录因子1、上皮细胞膜抗原阴性；肿瘤结节内及周边见个别CD3、CD1a、末端脱氧核苷酸转移酶阳性的不成熟T细胞，间质大量CD20阳性的B细胞，套区、边缘区及部分肿瘤细胞bcl-2阳性，肿瘤细胞及淋巴细胞EBER均阴性。Ig基因重排检测提示B细胞为多克隆增生。 结论： MNT是一种罕见的胸腺瘤，好发于中老年人，无明显症状，完整切除后，预后良好，诊断需结合临床及病理，排除其他类型的胸腺瘤。.
Keywords: Diagnosis, differential; Immunophenotyping; Thymoma.