[Clinicopathological characteristics of NTRK-rearranged mesenchymal tumors in childhood].

Objective: To investigate the clinical and pathological features of pediatric NTRK-rearranged tumors. Methods: Four NTRK-rearranged soft tissue tumors and one renal tumor at Shanghai Children's Medical Center, Shanghai Jiaotong University and Singapore KK Women's and Children's Hospital from January 2017 to September 2019 were identified. Pan-TRK immunohistochemistry, and the ALK and ETV6 gene break-apart fluorescence in situ hybridizations (FISH) were performed. NTRK gene rearrangement was detected using sequencing-based methods. Results: There were 3 males and 2 females in this study. The patients were between 3 months and 13 years of age. Histologically, the tumors were infiltrative spindle cell tumors with variable accompanying inflammatory cells. Immunohistochemistry showed positive reactivity for pan-TRK in all tumors, with nuclear staining for NTRK3 fusion, and cytoplasmic staining for NTRK1 fusion. The molecular testing revealed NTRK gene fusions (one each of TPM3-NTRK1, ETV6-NTRK3 and DCTN1-NTRK1, and two cases of LMNA-NTRK1). Two patients were receiving larotrectinib. The others were are well without disease, with follow-up durations of 9 to 29 months. Conclusions: NTRK-rearranged mesenchymal tumors from soft tissue sites and kidney are identified. A novel DCTN1-NTRK1 fusion is described. Pan-TRK immunohistochemistry is useful for diagnosis. NTRK-targeted therapy may be an option for unresectable, recurrent or metastatic cases.目的： 探讨儿童NTRK重排间叶源性肿瘤临床和病理学特征，以提高对该类疾病的认识。 方法： 收集上海交通大学医学院附属上海儿童医学中心及新加坡KK Women′s and Children′s Hospital从2017年1月至2019年9月5例手术切除标本，采用EnVision法检测免疫组织化学表型，荧光原位杂交（FISH）检测相关基因并对NTRK基因重排进行克隆性分析。 结果： 该组5例患儿，3例男性，2例女性。年龄从3个月到13岁，部位包括软组织（膝、胸腔、腹壁）和肾，肿瘤大小为4.5~12.5 cm。组织学检查主要呈梭形细胞肿瘤，浸润性生长，可伴有炎性细胞。免疫表型上，肿瘤细胞阳性表达Pan-TRK，分子检测均存在NTRK基因重排，包括DCTN1-NTRK1的发现。除2例目前接受靶向药物治疗，其余均为无疾病进展病例，随访时间9~29个月。 结论： NTRK重排间叶源性肿瘤，其肿瘤发生部位广泛，组织学图像多变。免疫组织化学Pan-TRK可以帮助诊断，NTRK基因检测确认其存在重排是诊断的金标准，对不能完整切除或有复发、转移病例建议靶向药物治疗。.