Institute of Pathology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
Thorac Surg Clin. 2011 Feb;21(1):25-31. v-vi. doi: 10.1016/j.thorsurg.2010.08.010.
The second edition of the World Health Organization (WHO) classification of thymic tumors (2004) has resumed the previous separation of thymic carcinomas (TCs) from thymomas. This "reseparation" was mainly based on new genetic data. Consequently, it is no longer recommended to label TCs as type C thymomas. TCs are very heterogeneous and comprise squamous, basaloid cell, mucoepidermoid, neuroendocrine, and many other subtypes. They resemble morphologic mimics in other organs and are labeled accordingly. However, only thymic squamous cell carcinomas (TSCCs) and lymphoepithelioma-like carcinomas are relatively common. For TSCCs, quite specific immunohistochemical markers (eg, CD5, CD70, CD117, CD205, FOXN1) and chromosomal gains and losses have been defined that help to distinguish TSCCs not only from malignant thymomas but also from pulmonary squamous cell carcinomas. Recognition of these differences is clinically important, because the prognosis of TSCC is better compared with the other TC subtypes and also compared with lung tumors. Considering the need to treat advanced TC more effectively, disparate findings in predictive molecular markers (eg, KIT mutations in TSCC, but not in thymomas) suggest that targeted treatments will have to be different in thymomas and TC. Preliminary data from single case collections and small treatment trials support this prediction.
世界卫生组织（WHO）2004 年版胸腺瘤（thymoma）分类方案恢复了前一版将胸腺癌（thymic carcinoma，TC）与胸腺瘤分开的分类方法。这种“再分离”主要基于新的遗传学数据。因此，不再建议将 TC 归为 C 型胸腺瘤。TC 是一种高度异质性肿瘤，包含鳞状细胞癌、基底样细胞癌、黏液表皮样癌、神经内分泌癌等多种亚型。它们与其他器官的形态学类似物相似，因此被相应地标记。然而，只有胸腺鳞状细胞癌（thymic squamous cell carcinoma，TSCC）和淋巴上皮样癌相对常见。对于 TSCC，已经定义了一些非常特异的免疫组织化学标志物（如 CD5、CD70、CD117、CD205、FOXN1）和染色体获得与缺失，这些标志物有助于将 TSCC 不仅与恶性胸腺瘤区分开来，还与肺鳞状细胞癌区分开来。认识到这些差异具有重要的临床意义，因为与其他 TC 亚型以及肺肿瘤相比，TSCC 的预后更好。考虑到需要更有效地治疗晚期 TC，预测性分子标志物（如 TSCC 中的 KIT 突变，但胸腺瘤中没有）的不同发现表明，针对胸腺瘤和 TC 的靶向治疗可能会有所不同。来自单个病例集和小型治疗试验的初步数据支持这一预测。
