Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A diffuse interstitial pattern has improved , with residual interstitial opacities predominantly at the lung bases . There are no confluent areas of consolidation . A few scattered linear areas of atelectasis are demonstrated in the left mid and both lower lungs suggestive of linear atelectasis . Additionally , there is apparent bronchial wall thickening in the lower lobes . Heart size , mediastinal and hilar contours are within normal limits , with stable tortuosity of the thoracic aorta .
    OUTPUT:
    
Improving diffuse interstitial abnormality , which may be due to an atypical pneumonia . Differential diagnosis includes drug reaction and interstitial edema , although there are no supporting findings to suggest volume overload or CHF .