Fig. 9. A 57-year-old man with a squamous cell carcinoma.

There is a cavitating mass with an air-fluid level (arrows) in the periphery of the left upper lobe on chest radiograph, which can be interpreted as a lung abscess or tuberculosis. Contrast-enhanced chest CT shows a mass in the apex of the left lung with necrosis and large cavitation and relatively thin medial wall. However, the uneven thickening of the lateral cavity wall (arrows in upper image) and enhancing mural nodules projecting into the lumen (arrow in lower image) suggest malignancy.