Case Report: Three cases of lung large cell neuroendocrine carcinoma with clinicopathological features of SMARCA4 (BRG1) deficiency

SD-LCNEC is a rare and clinically aggressive carcinoma, often presenting with lymph node metastasis at the initial stage. Its morphology is equivalent to LCNEC; however, immunohistochemical staining indicates the absence of SMARCA4 and a reduction in neuroendocrine markers and TTF-1. There is no standardized treatment, but SMARCA4 may serve as a potential therapeutic target. Accurate identification of the molecular subtype of SD-LCNEC is crucial.