伴有淋巴样间质的微结节型胸腺瘤6例临床病理分析

Micronodular thymoma with lymphoid stroma:morphological,immunological and prognostic features of six cases

目的探讨伴有淋巴样间质的微结节型胸腺瘤(MNT)的临床病理特征、免疫组化、诊断与鉴别诊断及其预后。方法回顾性分析6例MNT的临床相关资料及病理特征,对其进行HE及免疫组化Eili Vision法染色,并复习相关文献。结果 6例患者年龄53~77岁,平均年龄61.8岁,男女之比为5∶1。5例为体检时发现,1例以胸闷为主诉检查发现。CT提示均为前纵隔占位。镜检由富于淋巴细胞的间质所分隔的散在或融合成团的上皮细胞结节,淋巴细胞间质中常见含有生发中心的淋巴滤泡结构,背景中可见散在分布的小囊腔;其中1例伴发B2型胸腺瘤,镜下可见丰富的上皮细胞中散在不成熟的淋巴细胞。免疫组化:上皮细胞CK19(+)、EMA(-),上皮细胞巢内可见散在CD3(+)的T淋巴细胞,富于淋巴细胞的间质主要由CD20(+)的B细胞构成淋巴滤泡结构,囊腔被覆上皮CK19和EMA均(+),CD3和CD5(+)的T细胞位于滤泡间区,而CD99(+)的不成熟T细胞主要位于淋巴间质中,上皮细胞团中少见。术后随访,1例不明原因死亡,其余存活,无复发及转移。结论 MNT是一种罕见的胸腺上皮性肿瘤,预后良好。具有特征性病理表现,结合发生部位、影像学资料、组织病理学特点及免疫组化标记可以作出准确诊断。

Objective To investigate the clinical and pathological features,immunohistochemical findings,diagnosis,differential diagnosis and prognosis of micronodular thymoma with lymphoid stroma（ MNT）.Methods The clinical data and pathologic features of 6 cases of MNT were analyzed retrospectively by hematoxylin-eosin staining and the immunohistochemistry,and the related literatures were reviewed.Results There were 5 male,1 female patients,aged from 53 to 77 years,with average of 61.8 years.5 cases were found in the physical examination and one case presented with chest pain as the main complaint.All cases were found in the pre-mediastinal portion by the imaging CT.Microscopically,the classic phenotype showed a pattern architecture characterized by the scattered or fusion into the group of epithelial cell clusters separated by the rich lymphoid stroma with prominent germinal centers of the lymphoid follicle structure.One case was associated with B2 type thymoma.Immunohistochemical staining showed that epithelial cells were positive for CK19,but negative for EMA.The CD3（ ＋） mature T cells were scattered in the epithelial cell nest.Lymphocyte stroma was mainly positive for the CD20 ＋ B cells constituted by lymphoid follicle structure,CD3 and CD5（ ＋） T cells were located in the intercellular region,and CD99（ ＋） immature T cells were mainly located in the lymphatic stroma,and epithelial cell clusters were rare.No tumor recurrence and metastasis were observed after from 1.17 to 89.27 months post-surgery follow-up.Conclusion MNT is a rare thymic epithelial tumor with a good prognosis.With distinctive pathological characteristics,a reliable diagnosis of MNT requires information about the tumor location,image features,histopathological characteristics and immunohistochemical staining.