Correct!
4. The patient owns two parakeets
The historical point that the patient works as a sandblaster would suggests the possibility of silicoproteinosis, which, at thoracic CT appears identical to pulmonary alveolar proteinosis (PAP). PAP often appears as “crazy paving” at CT- multifocal ground-glass opacity associated with interlobular septal thickening and intralobular lines, frequently associated with a sharp demarcation between normal and abnormal lung- but that pattern is not present on the CT scans presented. The historical point of long term, heavy smoking suggests the possibility of smoking-related lung disorders, which could have multiple manifestations at thoracic CT, including upper lobe nodules / cavities (Langerhans cell histiocytosis), ground-glass opacity centrilobular nodules and/or areas of multifocal or diffuse ground-glass opacity (respiratory bronchiolitis-interstitial lung disease and desquamative interstitial pneumonia), and basal, posterior, subpleural ground-glass opacity and reticulation (smoking-relate fibrosis), but often these findings are associated with emphysema, which is absent on all the CT scans presented. The historical point of stem cell transplant would suggest the possibility of constrictive bronchiolitis as a manifestation of graft-versus-host disease. The earliest CT (Figure 3), perhaps the CT obtained 4 years prior to presentation (Figure 4) as well, could be consistent with that diagnosis, given that the presence of lobular low attenuation on these scans suggests the presence of small airway obstruction. However, areas of ground-glass opacity were developing even at the time of the scan obtained 4 years prior to presentation (Figure 4), and later CTs, including the presentation CT, clearly show progressive fibrotic lung disease, which is not typical for graft-versus host disease. The historical point that that patient may have an esophageal disorder should raise the possibility of aspiration. The progressive fibrotic abnormalities in the bases is potentially consistent with that consideration, but the basal sparing present on the presentation CT (Figure 2) and the additional features suggesting small airway obstruction suggest an alternative consideration. The historical point that the patient owns two parakeets suggests the possibility of hypersensitivity pneumonitis, and the imaging sequence presented is very suggestive of that disorder.
Which of the following should be performed to establish the diagnosis for this patient? (Choose the correct answer to move to the next panel)