Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Increased retrocardiac density is again noted corresponding to left lower lobe opacity on the lateral view . It is slightly improved from the previous study . There is no pleural effusion or pneumothorax . The heart size is top normal with normal cardiomediastinal silhouette .
    OUTPUT:
    
Slight interval improvement in left lower lobe opacity . In the setting of infectious symptoms , this could reflect a developing pneumonia . Repeat chest PA and lateral radiograph should be obtained in three to four weeks following treatment .