伴有淋巴样间质的微结节型胸腺肿瘤临床病理观察

Clinicopathological observation of micronodular thymic epithelial tumors with lymphoid stroma

目的探讨伴有淋巴样间质的微结节型胸腺肿瘤的临床病理学特点及预后指标。方法收集中日友好医院2014年1月至2018年1月间4例伴有淋巴样间质的微结节型胸腺肿瘤患者的临床资料,采用HE染色、免疫组织化学及原位杂交方法进行病理学观察。结果患者平均年龄(66.5±10.4)岁,男性1例,女性3例,均表现前纵膈占位,不伴有重症肌无力或自身免疫性疾病。肿瘤细胞呈微结节状分布,间质内见丰富淋巴细胞及淋巴滤泡形成。其中2例肿瘤细胞异型、核分裂象增多。肿瘤细胞表达CK、CK5/6,异型肿瘤细胞表达CD5、CD117及Bcl-2。3例在肿瘤细胞周边见少数不成熟T淋巴细胞,另1例未见Td T阳性细胞。肿瘤细胞及淋巴细胞均未测到EB病毒。最后诊断2例患者为伴有淋巴样间质微结节型胸腺瘤(micronodular thymoma with lymphoid stroma,MNT),1例为不典型MNT,1例为伴有淋巴样间质微结节型胸腺癌(micronodular thymic carcinoma with lymphoid hyperplasia,MNC)。术后随访4~42个月,无肿瘤复发。结论伴有淋巴样间质的微结节型胸腺肿瘤是一种罕见的胸腺肿瘤,包括了由良性至恶性的系列病变,但预后良好。诊断应结合临床病理特征,排除其他类型的胸腺肿瘤,治疗方法可相对保守。

Objective To investigate the clinicopathological features and prognosis of micronodular thymic epithelial tumors with lymphoid stroma. Methods Four cases of thymic epithelial tumours characterized by micronodular proliferation of tumour cells separated by abundant lymphoid stroma were collected in China-Japan Friendship Hospital from January 2014 to January 2018. Hematoxylin-Eosin staining,immunohistochemistry and in situ hybridization were performed to evaluate the pathological features. Results The average age of the 4 patients was（ 66. 5 ± 10. 4） years,including 1 male and 3 female. All the patients had an anterior mediastinal mass without myasthenia gravis or autoimmune disease. The tumors were characterized by micronodular proliferation of tumour cells separated by abundant lymphoid stroma with prominent germinal centers. Two of them showed cytological atypia and increased nuclear mitosis.Immunohistochemical study showed that the tumor cells were strongly positive for CK and CK5/6. Additionally,the tumor cells with atypia were positive for CD5,CD117 and Bcl-2. Scattered CD3,CD5 and Td T positive immature T lymphocytes were noted in and around tumor nodules in 3 cases. EB virus was not detected in both tumor cells and lymphocytes. Altogether,2 cases were diagnosed as micronodular thymoma with lymphoid stroma（ MNT）,1 atypical variant of MNT,and 1 micronodular thymic carcinoma with lymphoid stroma. There was no tumor recurrence in 4 to 42 months after the operation. Conclusion Micronodular thymic epithelial tumor with lymphoid stroma is a kind of rare thymus tumor,and may constitute a spectrum in the continuum of benign and malignant lesions. Their prognosis is good after complete resection. The diagnosis should be based on a combination of clinicopathologic features and other types of thymus tumor should be excluded. The treatment should be conservative.