Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a new opacity of the left lung base which may represent a combination of small pleural effusion and atelectasis however , an underlying infectious process can not be excluded . Evaluation of the cardiac silhouette is limited . Mediastinal contours are stable . There is tortuosity of the descending aorta . Flattening of the diaphragms is consistent with chronic obstructive lung disease . The right lung is essentially clear . There is no pneumothorax . There is redemonstration of a compression deformity in the lower thoracic spine .
    OUTPUT:
    
Increased left lung base opacity , may represent a combination of a small left pleural effusion and atelectasis . However , an underlying infectious process can not be excluded .