Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well inflated . A very subtle opacity projects over the left mid lung , just lateral to the left pulmonary artery . No nodule , effusion , or pneumothorax is present . The heart and mediastinal contours are normal .
    OUTPUT:
    
Subtle opacity in the left mid lung could represent an early pneumonia in the correct clinical context .