EGFR and lung adenocarcinoma: EGFR tyrosine kinase inhibitors and immunotherapy are standard treatment for NSCLC patients, but their effectiveness in lung adenocarcinoma with pulmonary enteric differentiation is unknown.<h4>Case presentation</h4>This report describes a 66-year-old man who was initially diagnosed with metastatic lung adenocarcinoma with <i>EGFR</i> mutation based on pleural fluid.