Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is persistent marked tracheal deviation to the right by the known left thyroid mass . The lungs are clear . The cardiac , hilar and mediastinal contours are normal . No pleural abnormality is seen .
    OUTPUT:
    
Persistent rightward tracheal deviation due to left lobe thyroid enlargement . Otherwise , clear lungs .