炎性肌成纤维细胞瘤（IMT）是一种中间肿瘤，很少发生在肝脏中。本研究的目的是分析最大的原发性肝IMT的临床病理和遗传特征。共找到10例病例（四名男性和六名女性，年龄为1-48岁，中位数为35岁），时间跨度为2011年至2021年，占所有器官系统中IMT的2.5％。组织学发现，在三名儿童中出现了肌成纤维细胞/成纤维细胞、炎症浸润和局灶性细胞稀少。免疫染色显示，六例病例（10例中的六例，60％）表现为ALK-弥漫胞质阳性，三例病例（10例中的三例，30％）表现为pan-TRK核阳性。ALK阳性的IMT中检测到高细胞密度模式，pan-TRK阳性亚组中观察到明显的胶原/黏液基质。荧光原位杂交（FISH）检测表明，在五例可解释的ALK阳性IMT中，有三例出现ALK重排，一例因样本质量差而检测失败。下一代测序表明，在一个IMT中检测到TFG :: ALK和FCHSD2 :: ALK融合和TP53突变。通过RT-PCR确诊ETV6 :: NTRK3融合，但在三例pan-TRK阳性IMT中，有两例FISH阴性结果。一种肿瘤没有检测到基因改变。其中一名患者在活检后1年去世，而九名患者在随访观察中存活且没有疾病证据（17-119个月）。本文描述了首例具有ETV6 :: NTRK3融合的原发性小儿肝IMTs。除常见的ALK阳性亚组外，NTRK3融合的比例较高。认识到临床病理和分子改变之间的关联对于准确诊断肝脏IMTs至关重要。 © 2023 John Wiley＆Sons Ltd。

Inflammatory myofibroblastic tumour (IMT) is an intermediate neoplasm and rarely occurs in the liver. The aim of this study was to analyse the clinicopathological and genetic features of the largest primary hepatic IMT.A total of 10 cases were identified (four males and six females aged 1-48 years, median = 35 years) from 2011 to 2021, which accounted for 2.5% of IMTs occurring in all organ systems. Histological findings revealed that myofibroblastic/fibroblastic cells with inflammatory infiltration and focal hypocellularity were observed in three children. Immunostaining showed ALK-diffuse cytoplasmic positive in six cases (six of 10; 60%) and pan-TRK nuclear positive in three cases (three of 10; 30%). Hypercellular pattern was detected in ALK-positive IMTs and obvious collagenous/myxoid matrix was observed in the pan-TRK-positive subgroup. ALK rearrangement was demonstrated in three of five interpretable ALK-positive IMTs by fluorescence in-situ hybridisation (FISH), and one case failed due to poor sample quality. Next-generation sequencing indicated an IMT with TFG::ALK and FCHSD2::ALK fusion and TP53 mutation. ETV6::NTRK3 fusion was confirmed by RT-PCR, but FISH-negative results were found in two of three cases with pan-TRK-positive IMTs. No genetic alteration was detected in one tumour. One patient died 1 year after biopsy, while nine patients survived without evidence of disease in the follow-up surveillance (17-119 months).This article describes the first example of primary paediatric hepatic IMTs with ETV6::NTRK3 fusion. Besides the common ALK-positive subgroup, the proportion of NTRK3 fusion is high. Recognising the association between clinicopathological and molecular alterations is critical to accurate diagnosis of hepatic IMTs.© 2023 John Wiley & Sons Ltd.