Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a moderate to large pleural effusion on the left with opacification of the left lower lobe . A combination of pleural effusion and parenchymal opacification is more extensive than on the prior study , now involving the superior segment of the left lower lobe . There is probably a trace pleural effusion only on the right . Fissures are minimally thickened but there is no parenchymal edema . The bones are probably demineralized . Degenerative changes affect each shoulder .
    OUTPUT:
    
Substantial pleural effusion on the left with either atelectasis or possibly pneumonia involving the left lower lobe . Whether this effusion represents a recurrent abnormality or a slowly persistent increasing one since the prior study is not certain .