Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear unchanged including moderate unfolding and calcification along the thoracic aorta . There is a left posterior focal opacity concerning for pneumonia . Mild interstitial disease is suspected in the periphery of the lower lungs . There is no pleural effusion or pneumothorax . The bones appear demineralized . Each acromiohumeral interval is again effaced , suggestive of rotator cuff pathology . There is also moderate rightward convex curvature centered along the mid - to - lower thoracic spine , as before .
    OUTPUT:
    
Opacity in the left lower lobe , worrisome for pneumonia . Since no remote comparison studies are available , however , differential considerations include more chronic atelectasis or scarring . Comparison to prior films may be helpful , if available .