摘要目的：探讨肺原发黏液表皮样癌（ PMC ）临床病理学特征及其表皮生长因子受体（ EGFR）基因突变的情况。方法分析55例手术切除PMC临床病理学特征、免疫组织化学特点、鉴别诊断。采用扩增阻滞突变系统（ ARMS）法对EGFR基因第18、19、20、21号外显子进行基因突变检测。结果患者女性32例，男性23例；发病年龄11～68岁，平均年龄为36岁。肿瘤均位于段及以上支气管内。肿瘤最大径0.7～5.5 cm，平均最大径2.4 cm，肿瘤无明显包膜，大多呈息肉样突向管腔，界限尚清。镜下观察PMC由产生黏液细胞、表皮样细胞和中间型细胞构成。53例为低级别，2例为高级别且均有淋巴结内肿瘤转移。免疫组织化学染色显示55例PMC中所有肿瘤细胞甲状腺转录因子1（TTF1）阴性、Napsin A 阴性、细胞角蛋白（CK）7阳性及间变性淋巴瘤激酶（ALK，Ventana D5F3）阴性；55例PMC中部分表皮样细胞及中间型细胞CK5／6、p63均阳性；并示52例PMC中部分表皮样细胞及中间型细胞p40阳性，3例p40阴性；55例PMC中产生黏液细胞CK5／6、p63及p40均阴性；低级别PMC中Ki-67阳性指数＜10％，高级别PMC中Ki-67阳性指数80％～90％。特殊染色显示腺腔内黏液样物质及产生黏液细胞PAS阳性。有随访结果的37例患者均无复发或死亡。31例PMC均无EGFR基因突变。结论 PMC是主要发生在中央气管的一种少见的涎腺型恶性肿瘤，患者大多为中青年，组织学上绝大多数为低级别，其患者预后较好，高级别淋巴结转移率较高。小活检诊断本病具有一定的局限性，缺乏TTF1的表达有利于与其他肺原发肿瘤鉴别。无EGFR基因突变。

abstractsObjective To investigate the clinicopathological features and epidermal growth factor receptor ( EGFR ) gene mutation of primary pulmonary mucoepidermoid carcinoma ( PMC ).Methods Fifth-five cases of PMC were included in the study;their clinicopathological, immunohistochemical features were evaluated, and in 31 cases, paraffin embedded specimens were subjected to mutation analysis of exons 18, 19,20 and 21 of the EGFR gene by ARMS method.Results There were 32 females and 23 males.The patients′age ranged from 11 to 68 years( mean 36 years).The tumor size ranged from 0.7 to 5.5 cm( mean 2.4 cm).The tumors were located in the segmental bronchus and upper segmental bronchus.The tumors were well-demarcated, had no obvious capsules, and protruded into the bronchial lumen.Microscopically, there were three types of tumor cells including squamous cells, mucin-producing cells and intermediate cells.Fifty-three cases were low grade, two were high grade and both showed lymph node metastases.Immunohistochemically the tumor cells were uniformly negative for TTF1, Napsin A and ALK ( Ventana D5F3) in all 55 cases.The tumor cells were positive for CK7, and some squamous and intermediate cells were positive for p63 and CK5/6 in all 55 cases;whereas they were positive for p40 in 53 cases.The mucin-producing cells were negative for CK5/6, p63 and p40, but were positive for PAS in all 55 cases.The Ki-67&nbsp;positive rate was <10%in the low grade PMC, and was about 80%-90%in the high grade cases.Follow-up information was available in 37 patients, with no recurrence or death.There were no EGFR gene mutations in all 31 patients of PMC.Conclusions PMC is a rare malignant salivary gland-type tumor occurring mainly in the central trachea of young patients.Most PMCs are low grade with good prognosis.The rate of lymph node metastasis of high grade PMC is high.Diagnosing PMC in small biopsies could be problematic.The lack of TTF1 expression is helpful to differentiate from other primary lung cancers.There is no EGFR gene mutation in PMC.