Correct!
1. The thoracic CT shows a fibrotic process distinct from most idiopathic interstitial pneumonias
The thoracic CT shows peripherally distributed coarse linear and reticular abnormalities associated with subpleural cystic change, the latter related to honeycombing. Some architectural distortion is present. These features are typical of fibrotic lung diseases. The presence of findings suggesting fibrosis argues strongly against lymphangitic carcinomatosis- this disorder is not characterized by fibrosis. There are no features that specifically suggest active infection, such as areas of ground-glass opacity unassociated with findings of fibrosis, consolidation, or nodules. While usual interstitial pneumonia / idiopathic pulmonary fibrosis merits consideration for the imaging findings, the distinct subpleural sparing of the extreme costophrenic angles argues against this disorder. Smoking-related disorders may show wide variety of findings at thoracic CT, including emphysema, nodules and cysts / cavities (with Langerhans cell histiocytosis), areas of ground-glass opacity which may be centrilobular, to basal reticular changes. Emphysema, nodules, cavities, and ground-glass opacity are not evident on this study, and, when reticulation occurs as a manifestation of smoking-related lung changes, that finding is typically seen in the setting of emphysema, which is lacking. The best answer among those listed is choice “1”- features of fibrosis are present, but the conspicuous extreme costophrenic angle sparing argues strongly against certain idiopathic interstitial pneumonias, such as usual interstitial pneumonia / idiopathic pulmonary fibrosis and non-specific interstitial pneumonia.
Further clinical course: Older thoracic CTs from 6 years (Figure 3), 4 years (Figure 4), and 2 years prior to presentation (Figure 5) became available for review.
Figure 3. Panels A-F: Representative static thoracic CT displayed in lung windows from 6 years prior to presentation. Lower panel: movie of thoracic CT scan displayed in lung windows.
Figure 4. Panels A-F: Representative static thoracic CT displayed in lung windows from 4 years prior to presentation. Lower panel: movie of thoracic CT scan displayed in lung windows.
Figure 5. Panels A-F: Representative static thoracic CT displayed in lung windows from 2 years prior to presentation. Lower panel: movie of thoracic CT scan displayed in lung windows.
Which of the following statements regarding these CT examinations is most accurate? (Choose the correct answer to move to the next panel)