婴儿型纤维肉瘤5例靶向治疗的临床病理特征与分子遗传学分析OA北大核心CSTPCD

Purpose To investigate the clinicopathological features,immunophenotypic and molecular genetic characteris-tics infantile fibrosarcoma(IFS)with targeted therapy.Meth-ods Clinical data of 5 cases of IFS treated with targeted therapy were collected.Immunohistochemistry EnVision two-step method was used to analyze the expression of pan-TRK,NGF,NT3 and BDNF.FISH method and NGS was used to detect the NTRK gene.Its clinical pathological characteristics and the prognosis after TRK inhibitor treatment were analyzed,and relevant litera-tures were reviewed.Results Microscopically,3 cases showed spindle tumor cells arranged in an interwoven bundle or fishbone like pattern,1 case was mostly primitive round tumor cells,and 1 case had hemangiopericytoma-like pattern.Immunohistochem-istry showed diffuse expression of pan TRK in 3 cases and focal expression in 2 cases.NGF was strongly expressed in 1 case,NT3 and BDNF was negative.FISH detection using NTRK1/2/3 split probe in 5 cases of IFS showed NTRK gene breakage.Fur-ther verification by EVT6 split probe and RNA-seq next-genera-tion sequencing confirmed ETV6-NTRK3 fusion in 4 cases and LMNA1-NTRK1 fusion in 1 case.After biopsy/complete resec-tion,all patients were treated with TRK inhibitors.One case un-derwent tumor reduction and resection tumor cells disappear-ance,and NTRK gene fusion disappeared.The follow-up period was 27-62 months,and the prognosis of the patients was good.Conclusion NTRK gene fusion is a molecular feature of IFS,and TRK is an important therapeutic target for IFS patients with NTRK gene fusion.TRK inhibitors have high efficacy and safe-ty.