Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low accentuating heart size and vasculature . Mild cardiomegaly is stable . Hilar and mediastinal contours are normal . Right lung and left apex are clear . Left base opacity is new . There is no pneumothorax .
    OUTPUT:
    
New left base opacity representing a combination of atelectasis and effusion .