Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable upright frontal chest radiograph demonstrates interval increase in interstitial pulmonary edema , now moderate . There is no large pleural effusion , or pneumothorax . The cardiac silhouette is unchanged , and normal in size . The mediastinal contours remain normal .
    OUTPUT:
    
Increase in now moderate pulmonary edema , though the heart size remains normal . Differential diagnosis includes atypical infection , drug reaction , or cardiogenic pulmonary edema . This might also represent an acute exacerbation of chronic interstitial lung disease as acute interstital pneumonitis .