Chest radiograph shows an ill-defined infiltration (arrow) in the right upper lobe and reticular densities in the both basal lungs. HRCT scans show honeycombing in periphery of the both lung and a focal infiltration with spiculated margin and traction bronchiectasis, suggesting fibrotic mass in the right upper lobe anterior segment. Honeycomb cysts are also noted in the peripheral portions of the both lower lobes.

Brief Discussion

    It is well recognized that idiopathic pulmonary fibrosis (IPF) is associated with lung cancer at a relatively high rate (about 14 times) compared with that of the general population without fibrosis. Lung cancer in IPF develops mostly in the peripheral portion and the lower lobe, where advanced fibrosis predominates. Squamous cell carcinoma and small cell carcinoma, which occurs mainly in the large bronchi, are frequently found in the peripheral region of the lung in the patient with IPF. However, this fact is not surprising, because squamous epithelial metaplasia and proliferation can also occur in the terminal airways. As to the peripheral origin, lung cancer with IPF is somewhat different from the so-called scar carcinoma of the lung. Namely, scar carcinoma occurs predominantly in the upper lobes and a relatively large population of this type is adenocarcinoma.
    Chest radiographic findings of lung cancer associated with IPF are nodular, linear densities, or a honeycomb pattern. Typical CT patterns of lung cancer are ill-defined lesions mimicking air-space consolidation at the peripheral portion where the most advanced fibrosis occurs.

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