Correct!
4. The thoracic CT shows multiple, thin-walled pulmonary cysts
The unenhanced thoracic CT shows multiple, bilateral, thin-walled cysts, without significant internal architecture, distributed fairly evenly throughout the upper, mid, and lower lungs. The cysts are slightly larger at the lung bases. No pulmonary nodules are present. The lesions present are best characterized as thin-walled cysts, rather than cavities or cavitary pulmonary nodules because of the lesions show very thin walls of uniform thickness with virtually no complexity. Typically, lesions that are referred to as “cavitary” are formed by tissue necrosis, and as a result, often have walls of varying thickness, internal architecture that may be nodular, and/or internal air-fluid levels; such features are lacking in this case. Centrilobular emphysema typically manifests at thoracic CT as small areas of circumscribed low attenuation without a definable wall, often showing a centrally positioned internal “dot” representing the centrilobular artery- this morphology is distinct from the morphology of the cystic lesions in this patient. Furthermore, centrilobular emphysema usually predominates in the upper lobes, whereas the cystic lesions in this patient are relatively evenly distributed in the upper, mid, and lower lungs. Finally, the patient was a non-smoker, further implicating a process other than centrilobular emphysema. Interstitial emphysema appears as linear areas of gas lucency tracking along the bronchovascular bundles, often associated with pneumomediastinum and subcutaneous emphysema, both of which are lacking in this patient. No features typical of fibrotic lung disease at CT- such as linear and reticular abnormalities, traction bronchiectasis, architectural distortion, and honeycombing- are not seen).
Which of the following assessments would be suggestive of the correct diagnosis in this patient, given the thoracic CT findings? (Click on the correct answer to proceed to the next panel)