Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . There is no pleural effusion or pneumothorax . Extensive pulmonary abnormalities appear unchanged . These are not fully characterized , but suggest extensive scarring or interstitial disease that may also coincide with underlying emphysema and probably bronchiectasis ; chronic infection is a differential diagnosis . There is no evidence of superimposed acute disease .
    OUTPUT:
    
Extensive underlying pulmonary abnormality , not significantly changed over the fairly short interval . No definite evidence of acute disease , however . Differential considerations include chronic infection in the setting of background lung disease . Correlation to more remote prior radiographs is recommended , if available . It may be otherwise be appropriate to consider chest CT to characterize further when clinically appropriate if the etiology is not known .