Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . Pulmonary vasculature is normal . As seen on the previous exam , there is continued patchy opacity in the left lung base with a small left pleural effusion . Right lung is grossly clear . No pneumothorax or new focal consolidation is seen . There are no acute osseous abnormalities .
    OUTPUT:
    
Persistent patchy left basilar opacity , potentially reflective of atelectasis , with small left pleural effusion .