Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is dense focal opacification in the mediastinal region extending from the level of the clavicles to just above the hemidiaphragms and is concerning for large mediastinal mass . The upper region of the trachea just above the carina is shifted to the right . The left mainstem bronchi appear is in a rule . The right main stem bronchi is now well visualized and may be compressed by the mass . There is no pleural effusion . There is a mild cardiomegaly without overt pulmonary edema . There is no pneumothorax . There are no acute bony abnormalities .
    OUTPUT:
    
1 . Large mediastinal mass extending from the level of the clavicle to just above the hemidiaphragm with mass effect : The upper trachea just above the carina is shifted to the right , left mainstem bronchus is narrowed .