Focal organizing pneumonia: CT appearance.

Abstract

To clarify the computed tomographic (CT) features of focal organizing pneumonia. The authors retrospectively studied CT scans of 18 patients with histologically proved focal organizing pneumonia. Chest radiographs in all 18 patients suggested bronchogenic carcinoma. Seventeen of the 18 lesions (94%) had an irregular margin, 10 (56%) had satellite lesions, nine (50%) had a pleural tag, and nine (50%) had an air bronchogram. The pneumonia could be classified into three types: Type A (n = 5) was a small round mass (pleural tag, n = 4). Type B (n = 7) was an oval mass with broad contact with the pleura (satellite lesions and convergence of peripheral vessels, n = 6). Type C (n = 6) was an oval mass along the bronchovascular bundle (satellite lesions, n = 3; pleural tag, n = 4). The CT features of focal organizing pneumonia show wide variation, and some type B and C lesions are suggestive of benign lesions. However, other lesions may be difficult to differentiate from bronchogenic carcinoma even with CT.