Abstract： To the Editor:Primary pulmonary enteric adenocarcinoma (P-PEAC),classified as a variant of lung adenocarcinoma with invasive mucinous adenocarcinoma,colloid adenocarcinoma,and fetal adenocarcinoma by the International Association for the Study of Lung Cancer,American Thoracic Society,and European Respiratory Society,was a rare type of lung adenocarcinoma.[1] In clinical practices,P-PEAC is easily confused with secondary pulmonary enteric adenocarcinoma (S-PEAC) that is manifested as pulmonary infiltration onset.Therefore,a retrospective study was carried out to investigate the difference of clinical manifestation,imaging presentation,immunohistochemical staining,and molecular pathological characteristics of P-PEAC and S-PEAC.