Thymic epithelial tumors (TET) are rare and large molecular studies are therefore difficult to perform. However, institutional case series and rare multi-institutional studies have identified a number of interesting molecular aberrations in TET, including gene fusions in a subset of these tumors. These gene fusions can aid in the diagnosis, shed light on the pathogenesis of a subset of tumors, and potentially may provide patients with the opportunity to undergo targeted therapy or participation in clinical trials. Gene fusions that have been identified in TET includeMAML2rearrangements in 50% to 56% of mucoepidermoid carcinomas (MAML2::CRTC1), 77% to 100% of metaplastic thymomas (YAP1::MAML2), and 6% of B2 and B3 thymomas (MAML2::KMT2A);NUTM1rearrangements in NUT carcinomas (most commonlyBRD4::NUTM1);EWSR1rearrangement in hyalinizing clear cell carcinoma (EWSR1::ATF1); andNTRKrearrangement in a thymoma (EIF4B::NTRK3). This review focuses on TET in which these fusion genes have been identified, their morphologic, immunophenotypic, and clinical characteristics and potential clinical implications of the fusion genes. Larger, multi-institutional, global studies are needed to further elucidate the molecular characteristics of these rare but sometimes very aggressive tumors in order to optimize patient management, provide patients with the opportunity to undergo targeted therapy and participate in clinical trials, and to elucidate the pathogenesis of these tumors.
胸腺上皮性肿瘤（TET）较为罕见，因此大规模分子研究难以开展。然而，机构病例系列研究和少数多中心研究已发现TET中存在一系列值得关注的分子异常，包括部分肿瘤中的基因融合现象。这些基因融合有助于诊断、揭示部分肿瘤的发病机制，并可能为患者提供接受靶向治疗或参与临床试验的机会。已在TET中发现的基因融合包括：50%至56%的黏液表皮样癌中存在MAML2重排（MAML2::CRTC1），77%至100%的化生性胸腺瘤中存在YAP1::MAML2融合，6%的B2和B3型胸腺瘤中存在MAML2::KMT2A融合；NUT癌中的NUTM1重排（最常见为BRD4::NUTM1）；透明细胞癌中的EWSR1重排（EWSR1::ATF1）；以及胸腺瘤中的NTRK重排（EIF4B::NTRK3）。本综述聚焦于已发现融合基因的TET，探讨其形态学特征、免疫表型、临床表现以及融合基因的潜在临床意义。未来需要开展更大规模、多中心、全球性的研究，以进一步阐明这些罕见但有时极具侵袭性肿瘤的分子特征，从而优化患者管理、为患者提供靶向治疗和临床试验机会，并深入揭示这些肿瘤的发病机制。
肿瘤(癌症)患者之家