粗针穿刺活检在纵隔T淋巴母细胞淋巴瘤与B1型胸腺瘤鉴别诊断中的价值

The value of core needle biopsy in differential diagnosis of mediastinal T lymphoblastic lymphoma and type B1 thymoma

目的分析纵隔T淋巴母细胞淋巴瘤(T-LBL)和B1型胸腺瘤病例的临床和病理学特点,提高粗针穿刺活检在这两种疾病鉴别诊断中的准确性。方法收集连续诊断的34例T-LBL和10例B1型胸腺瘤患者作为研究对象,均接受纵隔粗针穿刺活检获取标本,并经手术标本病理诊断确认。收集两组患者的临床资料,对比其粗针穿刺活检标本的组织病理学和免疫表型的差异。结果 T-LBL患者以小于30岁为主(73%),男性发病明显多于女性,男女比3.3:1。B1型胸腺瘤平均年龄43岁(40岁以上占50%),男女比2:3。T-LBL患者均有胸闷、气短、咳嗽等临床症状;B1型胸腺瘤患者中3例出现胸闷气短症状,2例出现重症肌无力症状。影像学特征:两组患者均为前纵隔单发肿物,肿块>10cm者在T-LBL患者中占88%,在B1型胸腺瘤患者中仅占50%。T-LBL患者全部可见肿瘤侵犯引起的胸腔或心包腔积液,而B1型胸腺瘤无此特征。病理学特征:T-LBL的瘤细胞在纤维组织中呈"列兵样"浸润性生长(65%),有骨骼肌组织侵犯(41%)和肿瘤性坏死(21%),而B1型胸腺瘤无此特征。所有B1型胸腺瘤均保留胸腺小叶结构,可见粗大纤维间隔,但仅3%的T-LBL保留胸腺小叶结构。免疫组化染色显示所有B1型胸腺瘤均可见完整的细胞角蛋白网,但T-LBL的细胞角蛋白网破坏。T-LBL和B1型胸腺瘤出现周围脂肪组织浸润的比例有差异,分别为59%和20%。结论 T-LBL与B1型胸腺瘤在患者性别、发病年龄、临床症状及影像学改变上有明显差异,以病理学特征的改变最具鉴别意义。密切联系临床表现与组织病理学改变有助于提高纵隔粗针穿刺活检在两种疾病鉴别诊断中的价值。

Objective To analyze the clinical and pathological characteristics of T lymphoblastic lymphoma（T-LBL） and type B1 thymoma in the mediastinum,and to improve the accuracy of differential diagnosis between two diseases.Methods Pathology of consecutive 34 cases of T-LBL and 10 cases of type B1 thymoma were reviewed in this study.All the initial diagnosis was made with core needle biopsy specimens of mediastinal masses and confirmed by subsequent chemotherapy and/or excision biopsy specimens.The clinical and pathological features of T-LBL and type B1 thymoma were compared by reviewing clinical records and analysis of HE and immunohistochemical staining sections.The chi-square test was used for statistic analysis.Results The mean age of the patients with type B1 thymoma was 43 years,and the ratio of male to female was 2：3,while the patients with T-LBL were much younger（with mean age of 25,73% of them younger than 30 years old） and the male to female ratio was 3.3：1.All the T-LBL cases presented symptoms including chest tightness,shortness of breath and cough.Three patients of thymoma complained of chest tightness and shortness of breath,and 2 cases presented symptoms of myasthenia gravis.Imaging examination showed solitary mass in anterior mediastinum in patients of both groups,88% of the T-LBL patients had mass10cm,while accounting for 50% in B1 thymoma patients.Concurrent pleural effusion was only observed in the T-LBL patients.Histopathologically,T-LBL and thymoma showed significant differences,including the infiltration of tumor cells in fibrous tissue（65% in T-LBL vs 0% in thymoma）,invasion of peripheral fat tissue（59% vs 20%）,invasion of skeletal muscle（41% vs 0%）,tumor necrosis（21% vs 0%）,and remaining of thymus lobular structure was found in only 3% of T-LBL.Intact cytokeratin network was shown in B1 thymoma（100%） by immunohistochemical staining.Conclusions Patients＇ gender,age,clinical features and imaging features,especially pathological characteristics were remarkable different between T-LBL and type B1 thymoma.Combining clinical manifestations and pathological changes will help to improve the accuracy of core needle biopsy in differential diagnosis of T-LBL and thymoma.