Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a focal opacity in the left lung base near the left heart border , which may represent a new or resolving pneumonia , likely in the inferior lingular segment . There is no pleural effusion , pulmonary edema or pneumothorax . The heart and mediastinal contours are normal .
    OUTPUT:
    
Left lung base opacity may represent an early or resolving pneumonia . Recommend follow up CXR in 4 weeks to document resolution .