[Clinicopathological features of NTRK3 gene rearrangement papillary thyroid carcinoma].

Objective: To investigate the clinicopathological features and differential diagnosis of NTRK3 gene rearrangement thyroid papillary carcinoma (PTC). Methods: The PTC cases without BRAF V600E mutation were collected at Fujian Provincial Hospital South Branch from January 2015 to January 2020. The cases of NTRK3 gene rearrangement PTC were examined using immunohistochemistry and fluorescence in situ hybridization (FISH). The clinical data, histopathological characteristics, immunohistochemical features and molecular pathological changes were retrospectively analyzed. Data from the TCGA PTC dataset and the literature were also studied. Results: A total of 3 PTC cases harboring NTRK3 gene rearrangement were confirmed. All the patients were female, aged from 26,49,34 years. Histologically, two of them demonstrated a multinodular growth pattern. Only one case showed prominent follicular growth pattern; the other two tumors showed a mixture of follicular, papillary and solid growth patterns. All tumors showed a typical PTC nuclear manifestation, with some nuclear pleomorphism, vacuolated foci and oncocytic features. The characteristic formation of glomeruloid follicular foci was present in two cases which also showed psammoma bodies, and tumoral capsular or angiolymphatic invasion. The background thyroid parenchyma showed chronic lymphocytic thyroiditis. Mitotic rates were low, and no cases had any tumor necrosis. The pan-TRK and TTF1 testing was both positive in 3 cases, while S-100 and mammaglobin were both negative in them. FISH studies confirmed the NTRK3 gene rearrangement in all 3 cases. Studies on the TCGA datasets and literature revealed similar findings. Conclusions: NTRK3 gene rearrangement PTC is rare. It may be easily misdiagnosed due to the lack of histological and clinicopathological characteristics. Molecular studies such as pan-TRK immunostaining, FISH and even next-generation sequencing are needed to confirm the diagnosis. Immunohistochemistry of pan-TRK performed in the PTC cases without BRAF V600E mutation can be used as a good rapid-screening tool. With the emergence of pan-cancer tyrosine receptor kinase inhibitors, proper diagnosis of these tumors can help determine appropriate treatments and improve their outcomes.目的： 探讨NTRK3重排甲状腺乳头状癌（PTC）的临床病理学特征、诊断和鉴别诊断。 方法： 收集2015年1月至2020年1月福建省立医院南院诊断的BRAF V600E阴性的PTC病例174例。对这些病例行免疫组织化学染色和荧光原位杂交（FISH）检测，筛选出NTRK3重排PTC的病例。总结确诊病例的临床资料、病理学特征、免疫组织化学特点及分子病理学改变。同时复习相关文献，并对癌症基因组图谱（TCGA）相关PTC病例进行分析和总结。 结果： 共确诊3例NTRK3重排PTC，患者均为女性（年龄26、49和34岁）。镜下观察：2例呈多结节状浸润性生长，除1例主要为滤泡结构，其余2例均具有滤泡、乳头及实性混合结构。3例可见典型的PTC细胞核特征，并具有一定的核异质性，胞质透亮或嗜酸性，其中2例可见肾小球样小体形成。肿瘤背景均呈淋巴细胞性甲状腺炎改变，间质见沙砾体形成。并见淋巴结转移、脉管癌栓和被膜外侵犯等侵袭性特征，但均未见明确凝固性肿瘤坏死和核分裂象。免疫组织化学表达甲状腺转录因子1（TTF1）和pan-TRK，不表达S-100蛋白和Mammaglobin，FISH均检测到NTRK3重排。复习并分析相关文献及TCGA数据集病例显示了相似的结果。 结论： NTRK3重排PTC是一种罕见的PTC类型，因临床病理学特征不明显很容易漏诊、误诊，需要借助免疫组织化学染色pan-TRK，FISH甚至二代测序等技术明确诊断。对BRAF V600E阴性病例进行pan-TRK免疫组织化学染色具有很好地快速筛查作用。随着pan-TRK抑制剂出现，他们的识别可以帮助改善诊断和预后，并确定适当的治疗方法。.