Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . There has been interval development of a large right pleural effusion with associated compressive atelectasis of the right middle and right lower lobes and the lower portion of the right upper lobe . The cause of this effusion is unclear . The left lung is clear . Right heart border can not be defined in therefore heart size is difficult to assess . No pneumothorax is seen . Bony structures are intact .
    OUTPUT:
    
New large right pleural effusion with associated compressive atelectasis in the right middle and lower lobes . Thoracentesis may be considered .