Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear within normal limits . There is mildly prominent central interstitial opacification with areas of peribronchial cuffing , although similar to the prior examination . There is no free air . The osseous structures are unremarkable .
    OUTPUT:
    
Mild interstitial process . Mild vascular congestion , an inflammatory or infectious process of lower airways or atypical pneumonia could be considered as possible etiologies .