%0 Case Reports %T Mesenchymal-epithelial Transition Exon 14-skipping Mutation-positive Invasive Mucinous Adenocarcinoma of the Lung: First Case Treated with Mesenchymal-epithelial Transition-tyrosine Kinase Inhibitors. %A Okuzumi S %A Suzuki H %A Morinaga S %A Tamura M %A Minematsu N %J Intern Med %V 63 %N 12 %D 2024 Jun 15 %M 37952955 %F 1.282 %R 10.2169/internalmedicine.2540-23 %X 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.