The co-presence of malignant pleural mesothelioma (MPM) and lung cancer is rare. We report a 70-year-old male with exposure to asbestos. Chest computed tomography revealed a right mediastinal mass combined with an enlarged ipsilateral lymph node and left pleural effusion. Transbronchial lung biopsy revealed lung adenocarcinoma. Thoracoscopic examination revealed multiple left pleural nodules, leading to the diagnosis of MPM. Despite aggressive anticancer drug therapy, he expired due to disease progression 2.5 years after diagnosis. Autopsy confirmed an epithelioid MPM in the left pleura. MPM comorbidity in patients diagnosed with lung cancer should be considered, especially in those exposed to asbestos.