[Analysis of Clinicopathologic Features of 9 Cases of 
SMARCA4-deficient Non-small Cell Lung Cancer].

SMARCA4-deficient non-small cell lung cancer (SMARCA4-dNSCLC) is a rare primary lung malignancy. These diseases are not listed separately in the 2021 World Health Organization (WHO) classification of lung neoplasms, but they have special morphological, immunophenotypic and molecular genetic characteristics. This study aims to improve understanding of SMARCA4-dNSCLC by discussing the clinicopathological features, diagonosis and differential diagnosis of the disease.The clinical and imaging data of 9 cases of SMARCA4-dNSCLC diagnosed in Shanghai Changhai Hospital from January 2020 to March 2022 were collected. The clinicopathological features were analyzed by histological and immunohistochemical staining, and the literature was reviewed.The median age of 9 patients was 65 years old. Six men were smokers. The average maximum diameter of tumor was 3.3 cm. Six cases had been metastasized. The imaging showed that it was an infiltrating mass with unclear boundary and 3 cases invaded the pleura. Nine cases were diagnosed as SMARCA4-dNSCLC, which mainly showed three pathological forms including classic lung adenocarcinoma, mucinous adenocarcinoma and poorly differentiated carcinoma. Poorly differentiated tumor cells are epithelioid, syncytial or rhabdomyoid, the cytoplasm was rich, the cytoplasm could be completely transparent to eosinophilic, eosinophilic globules or small abscesses could be seen, showing solid flakes, with more inflammatory cells and flake necrosis in the stroma. Immunohistochemistry showed that SMARCA4 was negative in all cases and eight cases demonstrated cytokeratin 5.2 (CAM5.2) and cytokeratin 7 (CK7) was diffusely strongly positive, p40 was negative, thyroid transcription factor-1 (TTF-1) was negative in 6 cases, partially positive in 2 cases and diffusely positive in 1 case.SMARCA4-dNSCLC is a rare subtype of lung cancer with complex and diverse pathological morphology. The characteristic of immunohistochemical phenotype can assist in the diagnosis.【中文题目：伴有SMARCA4缺失的非小细胞肺癌 9例临床病理分析】 【中文摘要：背景与目的 SMARCA4缺失的非小细胞肺癌（SMARCA4-deficient non-small cell lung cancer, SMARCA4-dNSCLC）是一种罕见的原发于肺的恶性肿瘤。虽然2021版世界卫生组织（World Health Organization, WHO）肺肿瘤分类中并未将其单独列出，但这类肿瘤具有独特的形态学、免疫表型及分子遗传学特征。本研究通过探讨SMARCA4-dNSCLC的临床病理特征、免疫组化、诊断及鉴别诊断，以加深对该类肿瘤的认识。方法 收集2020年1月-2022年3月上海长海医院诊断的9例SMARCA4-dNSCLC的临床与影像学资料，通过组织学、免疫组化染色分析其临床病理特征并进行文献复习。结果 9例患者中位发病年龄65岁。6例男性均有吸烟史。肿瘤平均直径3.3 cm。6例转移。影像学提示为边界不清的浸润性肿块，3例伴胸膜侵犯。9例诊断为SMARCA4-dNSCLC，主要表现为3种病理形态，包括经典的肺腺癌、肺黏液腺癌及低分化癌。低分化肿瘤细胞上皮样、合体样或横纹肌样，胞质丰富，胞质可完全透明至嗜酸性，可见嗜酸性小球或小脓肿，呈实性片状，间质较多炎细胞及片状坏死。免疫组化显示SMARCA4均为阴性，8例细胞角蛋白（cytokeratin 5.2, CAM5.2）、细胞角蛋白7（cytokeratin 7, CK7）弥漫强阳性，P40均阴性，6例甲状腺转录因子1（thyroid transcription factor-1, TTF-1）阴性，2例部分阳性，1例阳性。结论 SMARCA4-dNSCLC是一类罕见的肺癌亚型，病理形态复杂多样，特征性的免疫组化表型可协助诊断。 】 【中文关键词：SMARCA4；肺肿瘤；病理学特征；诊断】.