Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest demonstrate mild pectus excavatum deformity of the chest , which silhouettes the right heart border . The lungs are clear and well expanded . The pleural surfaces and mediastinal contours are normal . The cardiac silhouette is normal in size .
    OUTPUT:
    
No acute chest abnormality .