Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a large central mass involving the right hilus and upper mediastinum , likely the cause of the central venous obstruction . The mass measures approximately 9 x 4 .5 cm . The lungs are hyperinflated and otherwise are clear . The heart is not enlarged . No pleural effusions or pneumothorax .
    OUTPUT:
    
Right hilar and mediastinal adenopathy , most likely malignant either bronchogenic carcinoma or lymphoma , responsible for referenced venous occlusion , presumably superior vena caval obstruction . An urgent CT thorax is suggested given the rapid central venous obstruction symptoms .