Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle focal opacity at the lateral left mid lung measures approximately 2 cm . The right lung is clear . No pleural effusion or pneumothorax is seen . The cardiac silhouette is top - normal . The aorta is mildly tortuous .
    OUTPUT:
    
Focal opacity in the lateral left mid lung measuring approximately 2 cm could be due to pneumonia . Recommend followup to resolution to exclude an underlying pulmonary lesion .