Objective: To investigate the clinicopathological characteristics and genetic mutations of SMARCA4-deficient lung adenocarcinoma. Methods: From January 2021 to April 2023 in the First Affiliated Hospital of Zhengzhou University, 42 cases of SMARCA4-deficienct lung adenocarcinoma were diagnosed and now analyzed. All cases were retrospectively studied using hematoxylin-eosin staining and immunohistochemistry. The clinicopathological features were reviewed. Next-generation sequencing (NGS) was performed to investigate the mutations of related genes. Results: Among the 42 cases, there were 35 biopsy and 7 surgical specimens. There were 38 males and 4 females. The male to female ratio was 9.5∶1.0, with an age range from 42 to 78 years. Thirty-three patients were smokers. Overall, 4 cases (9.5%), 2 cases (4.7%), 18 cases (42.9%) and 18 cases (42.9%) were at stages Ⅰ, Ⅱ, Ⅲ, and Ⅳ, respectively. Microscopically, all the cases were non-mucinous adenocarcinoma, without lepidic pattern. The morphology was diverse. Rhabdomyoid cells, tumor giant cells and tumor necrosis were present. Most of the tumor cells had eosinophilic cytoplasm and occasionally clear cytoplasm. Defined cell borders and variable cytoplasmic hyaline secretory globules could be found. Inflammatory cells infiltrated the tumor stroma. Immunohistochemistry showed 29 cases (69.0%, 29/42) expressed TTF1, 10 cases (40.0%, 10/25) expressed Napsin A, and 20 cases (100.0%, 20/20) expressed INI1. Forty cases (95.2%, 40/42) showed BRG1 loss in all tumor cells, while 2 cases (4.8%, 2/42) had partial BRG1 loss. PD-L1 (22C3) was positive in 59.2% of the cases (16/27). NGS revealed mutations in EGFR, ROS1, MET, RET and KRAS. Six cases (6/8) showed SMARCA4 mutation, while some cases were accompanied by mutations of TP53 (7/15), STK11 (4/8), and KEAP1 (1/8). Driver gene mutations were more common in women (P<0.05). Patients were followed up for 1-25 months. Four patients died and 20 patients' diseases progressed. Conclusions: SMARCA4-deficient lung adenocarcinoma lacks characteristic morphology. Most of them express TTF1 and harbor driver gene mutations. It is necessary to identify this subset of lung adenocarcinoma by carrying out BRG1 stain routinely on lung adenocarcinoma. These patients can then be identified and benefit from targeted therapies.
目的： 探讨SMARCA4缺失性肺腺癌临床病理学特征及基因突变情况。 方法： 收集郑州大学第一附属医院病理科2021年1月至2023年4月诊断为肺腺癌且伴有SMARCA4缺失病例42例，回顾性分析HE切片、免疫组织化学染色，总结临床病理特征，并随访患者生存情况。对部分病例进行二代测序。 结果： 42例SMARCA4缺失性肺腺癌，穿刺标本35例，手术标本7例。男性38例，女性4例，男女比例为9.5∶1.0。年龄42~78岁，平均年龄62岁。吸烟者33例，平均吸烟时长37年。有呼吸系统症状25例（59.5%）。TNM分期Ⅰ期4例（9.5%），Ⅱ期2例（4.7%），Ⅲ期18例（42.9%），Ⅳ期18例（42.9%）。肿瘤组织均为非黏液腺癌，无贴壁模式，大部分为低分化腺癌，组织形态多样，可见横纹肌样形态细胞、瘤巨细胞及坏死。肿瘤细胞胞质大部分嗜酸性，胞质内有嗜酸性小球，间质可见炎性细胞浸润及胆固醇结晶。免疫组织化学：29例（69.0%，29/42）表达甲状腺转录因子1（TTF1），10例（40.0%，10/25）表达Napsin A，20例（100.0%，20/20）INI1未缺失；40例（95.2%，40/42）肿瘤细胞BRG1完全缺失，2例（4.8%，2/42）为BRG1部分缺失；PD-L1（22C3）59.2%（16/27）阳性。二代测序检测发现表皮生长因子受体、ROS1、MET、RET及KRAS突变，6例（6/8）SMARCA4突变，7例（7/15）p53、4例（4/8）STK11及1例（1/8）KEAP1突变。驱动基因改变多见于女性患者（P<0.05）。随访1~25个月，4例死亡，20例进展。 结论： SMARCA4缺失性肺腺癌缺乏特征性的组织形态，大部分表达TTF1，少数病例有驱动基因的改变，有必要对肺腺癌常规进行BRG1免疫组织化学检测，筛选出此类病例，以便采用更精准的治疗。.