Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is complete opacification of the right hemithorax mild contralateral mediastinal shift . The right lung is nearly entirely collapsed . Sutures denote prior wedge resections from the left lung , otherwise clear . No left pleural abnormality . Given the clinical history , the right pleural abnormality has been developing slowly . .
    OUTPUT:
    
Massive right pleural effusion causing nearly complete collapse of the right lung .