Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Recently described focal left lower lobe opacity has rapidly improved . However , there is now a more diffuse reticular pattern present with mid and lower lung predominance , and accompanying bronchial wall thickening / peribronchial cuffing . Focal left upper lobe lung nodule with adjacent fiducial seed appears similar to the recent radiograph , and cardiomediastinal contours are stable as well . There are no pleural effusions or pneumothoraces .
    OUTPUT:
    
1 . Rapid resolution of focal left lower lobe opacity favoring atelectasis or aspiration as the likely etiology . 2 . Subtle bilateral mid and lower lung reticular opacities , for which the differential diagnosis includes evolving atypical pneumonia , interstitial edema , and drug reaction .