In 2021, the World Health Organization (WHO) recognized SMARCA4‐deficient undifferentiated thoracic tumor (SMARCA4‐UT), formerly known as SMARCA4‐deficient thoracic sarcoma (SMARCA4‐DTS), as a distinct entity that was different from SMARCA4‐deficient NSCLC, due to its unique histological, immunohistochemical, clinical, and prognostic features.14 The gene discussed is SMARCA4; the disease is non-small cell lung carcinoma.