Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest demonstrate well - expanded and clear lungs . Heart is normal in size and cardiomediastinal contour is unremarkable . There is no pleural effusion or pneumothorax . A tubular density posterior to the trachea may represent a thickened esophagus .
    OUTPUT:
    
1 . No acute intrathoracic abnormality . 2 . Possible esophageal thickening , clinical correlation recommended .