Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Widening of the left superior mediastinal contour is associated with rightward displacement of the tracheal air column and apparent symmetrical narrowing of the subglottic airway . Heart size is normal . Lungs are clear , and there are no pleural effusions . Scoliosis is noted .
    OUTPUT:
    
Right - ward displacement of proximal trachea with apparent subglottic narrowing . In the setting of left superior mediastinal widening , this is concerning for extrinsic compression the from enlarged left lobe of thyroid gland . By report , the patient has a history of goiter .