A 58-year-old woman visited our hospital complaining of persistent cough for one month. Computed tomography (CT) confirmed a middle mediastinal tumor centered on the tracheal bifurcation. A diagnosis of middle mediastinum thymic carcinoma (cT4N2M0 Stage IVb stage) was made from the tissue when the right main bronchial stenosis was relieved, and progressive disease (PD) was diagnosed despite the administration of cytotoxic anticancer drugs and radiotherapy. Next, oral administration of lenvatinib, a multityrosine kinase inhibitor (TKI), was started, and the dose was reduced or discontinued for 4 months due to side effects. Although stable disease (SD) was maintained, the patient had coughing symptoms, and CT confirmed a ground-glass opacity in the right upper lobe. The patient was discontinued as a side effect of lenvatinib, but a right pneumothorax developed, the opacity worsened, and steroid pulse therapy was performed. Tegafur-gimeracil-oteracil potassium (TS-1) was started as an anticancer agent, and although the opacities in the lung field showed an improvement trend, the tumor worsened and she died 305 days after starting lenvatinib.

Keywords: Pulmonary cavitation; Lenvatinib; Thymic carcinoma