Fig. 11. A 68-year-old man with a solitary cystic squamous cell carcinoma.

A. A thin-walled large cyst (arrows) in the left upper lobe and left pleural effusion are seen on the initial CXR.

B. Approximately 5 months later, the large cyst in the left upper lobe shows expansion, wall thickening, air-fluid level, and peripheral increased opacity (arrow), which can be interpreted as an infected lung cyst with pneumonia on CXR. Coronal contrast-enhanced chest CT shows mild irregularity in the wall of the solitary cystic lung cancer (arrow) and direct tumor invasion with bone destruction of the thoracic spine (arrowheads). Loculated left pleural effusion with rounded atelectasis is also seen in the left lower lobe.

CXR = chest radiograph