Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Progression of the left basal opacities compatible with pneumonia . The left costodiaphragmatic sulcus is not included in the exam . The right lung is unremarkable . The mediastinal and cardiac contours are unchanged . There are no pneumothorax and no pleural effusion .
    OUTPUT:
    
Progression of the pneumonia at the left lung base .