Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: It is difficult to precisely compare the size of the moderate - to - large left pleural effusion with prior chest x-ray from ___ from outside facility due to current upright positioning in comparison to supine positioning on prior , although it is probably stable . The left upper lung is partially aerated . The right lung demonstrates areas of linear atelectasis but is otherwise clear . Heart size is difficult to assess . The right hilum is unremarkable . The left hilum is obscured . There is no evidence of pneumothorax .
    OUTPUT:
    
Probable interval stability of moderate to large left pleural effusion , allowing for differences due to patient positioning in comparison to prior . Right lung linear atelectasis , otherwise clear . No right pleural effusion . No pneumothorax .