摘要目的:探讨炎性肌纤维母细胞肿瘤（inflammatory myofibroblastic tumor，IMT）的临床病理学特征、诊断与鉴别诊断要点。方法:收集江苏省人民医院病理科2010年5月至2020年5月诊治的32例IMT，观察其临床及组织病理学、免疫组织化学及分子病理特点，并复习相关文献。结果:患者男19例，女13例，年龄5~65岁（平均年龄37岁）。肺及纵隔10例，胃肠道、肠系膜/大网膜12例，膀胱5例，头颈部3例，小腿软组织及腹膜后各1例，其中4例为上皮样炎性肌纤维母细胞肉瘤（epithelioid inflammatory myofibroblastic sarcoma，EIMS），均位于腹腔。组织学肿瘤以梭形肌纤维母细胞及纤维母细胞增生为主，间质不同程度疏松水肿黏液变至胶原化，伴多少不等的慢性及急性炎性细胞浸润；EIMS以上皮样瘤细胞为主，间质水肿黏液变，浸润炎性细胞主要为中性粒细胞。免疫组织化学：肿瘤细胞表达间变性淋巴瘤激酶（ALK，25/32，78%），除4例EIMS均为核膜阳性外，其余IMT均为胞质阳性；肿瘤细胞还表达广谱细胞角蛋白（8/19）、平滑肌肌动蛋白（24/32，75%）、结蛋白（12/32，38%），其中4例EIMS均为结蛋白强阳性。15例行ALK荧光原位杂交检测显示12例（12/15）可见分离信号，以非经典断裂信号为主。3例行二代测序显示1例小腿IMT出现CLIP2-ALK融合，2例EIMS均示RANBP2-ALK融合。随访29例，22例无瘤生存，4例复发（其中3例克唑替尼治疗并带瘤生存），3例死亡（其中2例为EIMS）。结论:IMT形态学谱系广泛，需与多种良恶性肿瘤鉴别，免疫组织化学（抗体ALKp80、ALKD5F3）及荧光原位杂交检测（ALK断裂探针）可辅助IMT的诊断，不典型病例推荐二代测序检测。

abstractsObjective:To investigate the clinicopathological diagnosis and differential diagnosis of inflammatory myofibroblastic tumor (IMT).Methods:Thirty-two cases of IMT collected at the People′s Hospital of Jiangsu Province from May 2010 to May 2020 were evaluated for their clinical, histologic, immunohistochemical and genomic features, and relevant literature was reviewed.Results:There were 19 male and 13 female patients, with age ranging from 5 to 65 years (mean, 37 years). The tumors were located in the lung and mediastinum (10 cases), gastrointestinal tract and mesentery/omentum (12 cases), urinary bladder (5 cases), head and neck (3 cases), somatic soft tissue (1 case), and retroperitoneum (1 case). Four cases of epithelioid inflammatory myofibroblastic sarcoma (EIMS) were all located intra-abdominally. Histologically, the tumor cells were myofibroblasts and fibroblasts arranged in predominantly fusiform pattern, with variably edematous to myxoid background or sclerotic collagenized stroma, and variably mixed chronic or acute inflammatory cells infiltration. EIMS were composed mainly of epithelioid tumor cells, with myxoid stroma and numerous neutrophils. Immunohistochemically, the tumor cells expressed cytoplasmic ALK (25/32, 78%), whereas the four EIMS showed nuclear membrane ALK staining pattern. The tumor cells also expressed CKpan (8/19), SMA (24/32, 75%) and desmin (12/32, 38%); all four EIMS also showed strong positivity for desmin. Fluorescence in situ hybridization (FISH) for ALK gene rearrangement showed split apart signals in 12 of 15 cases, most commonly with atypical signals. Next-generation sequencing (NGS) was performed in three tumors and showed that one case of lower leg IMT harbored a novel CLIP2-ALK fusion, and two cases of EIMS harbored RANBP2-ALK fusion. Follow-up data were available in 29 patients. Twenty-two patients were alive with no evidence of tumor, four patients had tumor recurrences (three patients were treated with crizotinib and were alive with tumor), and three patients died of the disease (including two patients with EIMS).Conclusions:IMTs show a wide morphologic spectrum, and should be differentiated form a variety of benign or malignant tumors. Immunohistochemistry (ALKp80, ALKD5F3) and FISH (ALK break-apart probe) could assist the diagnosis of IMT, with NGS recommended for the atypical cases.