Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Bilateral parenchymal or opacities are noted . Most dense consolidation is identified at the left lung base , which has progressed since prior with silhouetting of the hemidiaphragm . Chronic distortion of the parenchyma markings seen at the right lung base . Cardiac silhouette is grossly unchanged . No acute osseous abnormalities .
    OUTPUT:
    
Left lung base opacity has progressed since prior . This opacity is part due to known underlying mass with likely component of postobstructive atelectasis and / or infection .