Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a large left pleural effusion which obscures the left heart border and left lung base . Underlying atelectasis or infectious process can not be ruled out . Scarring is noted adjacent to the left mediastinal border and there is upward retraction of the left hilus consistent with a history of left upper lobectomy and can also be a function of radiation change . There is no new focal consolidation , pneumothorax or significant pulmonary edema .
    OUTPUT:
    
Left pleural effusion and left paramediastinal scarring could be secondary to radiation changes . Underlying atelectasis or infectious process can not be ruled out .