Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . There is subtle increase in interstitial markings bilaterally which could be due to mild interstitial edema or atypical infection . No airspace consolidation is seen . There is no pleural effusion or pneumothorax . The cardiac and mediastinal silhouettes are unremarkable .
    OUTPUT:
    
Mild increase in interstitial markings bilaterally could relate to mild interstitial edema , although atypical infection is not excluded . Alternatively , it could relate to underlying chronic lung disease . However , this appears increased compared to ___ .