대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Focal Organizing Pneumonia

Radiologic Findings

Poorly-defined faint opacity is seen in right upper lobe on chest radiograph. HRCT scan show elongated nodule with speculated margin and CT-halo sign. Ectatic bronchus or small cavitation seen within the lesion. On chest MRI, the lesion appeared high signal intensity nodule on both T1- and T2-weighted images and is enhanced well after administration of contrast media.

Postlobectomy specimen consisted of right upper lobe, measuring 12x9x8 cm in size and 112.9 gm in weight. On sectioning, there was a gray-whitish relatively well-defined nodular lesion, measuring 1.5x1cm at the adjacent pleura. The other portion of lung parenchyma is unremarkable. Microscopic view (x100) of solid mass lesion showed pneumonitis with moderate fibrosis. Marked thickening of the vessel wall was the most prominent finding and large sized vein showed massive fibrotic thickening. The alveolar plugs showed myxoid change of matrix surrounding capillaries and lymphoplasma cell infiltration. Interstitium showed mild inflammatory infiltration.

Brief Review

Kono, et al classified the focal organizing pneumonia into three types: Type A was a small round mass (pleural tag). Type B was an oval mass with broad contact with the pleura (satellite lesions and convergence of peripheral vessels). Type C was an oval mass along the bronchovascular bundle (satellite lesions and pleural tag).
In recent study, Yang, et al analyzed 17 cases of focal organizing pneumonia. The lesions appeared as a nodule (n= 13) or a mass (n=13), ranging from 9 mm to 66 mm in diameter. Ground-glass opacity was seen in 6/13 (46%) nodules and 6.5/13 (50%) masses (k=.48) with an extent ranging from 5% to 75% (mean, 16%). In 4/26 (15%) patients, the extent was more than 50% of the lesion. They showed smooth (n=4), ovulated (n=8), spiculated (n=1), or lobulated and spiculated margin (n=13). On correlative analysis, nodule or mass on CT consisted histologically of intraalveolar exudate or microabscess, chronic inflammatory cell infiltration, fibrotic nodules, and polypoid granulation tissue in the alveolar or bronchiolar spaces. Ground-glass opacity consisted of interstitial fibrosis and chronic inflammatory cell infiltration and intraalveolar polypoid granulation tissue. Focal organizing pneumonia may simulate a lung cancer with variable appearances on CT and the findings reflect underlying histopathology of the disease.

References

1. Kono N, Ikezoe J, Johkoh T, Takeuchi N, Tomiyama N, Kido S, Kondoh H, Arisawa J, Kozuka T. Focal organizing pneumonia: CT appearance. Radiology 1993;189:119-123
2. Yang PS, Lee KS, Han J, Kim EA, Kim TS, Choo IW. Focal organizing pneumonia: CT and pathologic findings. J Korean Med Sci. 2001;16:573-578

Keywords

Lung, Non-infectious inflammation,