{Reference Type}: Case Reports {Title}: Mesenchymal-epithelial Transition Exon 14-skipping Mutation-positive Invasive Mucinous Adenocarcinoma of the Lung: First Case Treated with Mesenchymal-epithelial Transition-tyrosine Kinase Inhibitors. {Author}: Okuzumi S;Suzuki H;Morinaga S;Tamura M;Minematsu N; {Journal}: Intern Med {Volume}: 63 {Issue}: 12 {Year}: 2024 Jun 15 {Factor}: 1.282 {DOI}: 10.2169/internalmedicine.2540-23 {Abstract}: Mesenchymal-epithelial transition (MET) exon 14-skipping mutation (METex14) is rare in pulmonary invasive mucinous adenocarcinomas (IMAs), and the clinical impact of MET-tyrosine kinase inhibitors (TKIs) remains unknown. We herein report a 75-year-old woman with IMA harboring METex14 who was treated with the MET-TKI tepotinib. The lung tumor regressed over six months; however, the patient ultimately died of exacerbated interstitial lung disease (ILD), possibly associated with tepotinib. An autopsy revealed diffuse alveolar damage in pre-existing chronic fibrosis. We discuss how to pre-evaluate ILD deterioration risks and monitor TKI-induced lung toxicity during treatment.