[A case of left lung cancer associated with an aneurysm of the thoracic aorta].

A 61-year-old man was admitted to our hospital because of a left lung cancer. The chest x-ray film showed an irregular mass in the left upper lung field and the ill-defined left upper mediastinal border. A large portion of the aorta seen in the CT section above the aortic arch was understood to be aortic elongation. When a left pneumonectomy was performed, a saccular aneurysm of the distal aortic arch was found and resected under partial aortic clamping. Following the aneurysmectomy mediastinal dissection was performed in the normal way. The patient recovered uneventfully. The pathological specimens showed a pT2N1M0 squamous cell carcinoma with obstructive pneumonia and an arteriosclerotic aneurysm. There was no report of lung cancer associated with aneurysm of the thoracic aorta. In a patient with left lung cancer obliterating the left upper mediastinal border (the "silhouette sign") the aortic arch should be closely examined by MRI and/or angiography.