All cases demonstrated loss of SMARCA4 (BRG1) nuclear expression with retained INI-1.<h4>Conclusion</h4>Pulmonary SMARCA4-deficient undifferentiated carcinoma showed a reproducible aggressive CT imaging profile in this cohort, characterized by marked heterogeneity, necrosis or cavitation, multi-structure invasion, and conglomerated lymphadenopathy. The gene discussed is SMARCA4; the disease is undifferentiated carcinoma.