Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Interval placement of left - sided dual lead pacer device with lead extending to the expected positions of the right atrium right ventricle . Cardiac and mediastinal silhouettes are grossly stable . There is left upper to mid lung opacity , more consolidated peripherally , as also seen on recent prior head CT from ___ . As also mentioned on that study , differential diagnosis includes metastatic disease and / or post obstructive pneumonia . No pleural effusion or pneumothorax is seen . Punctate radiodensity is seen overlying the right hilum .
    OUTPUT:
    
Left upper to mid lung opacity , more consolidated peripherally , as also seen on recent prior PET - CT with concern for malignant involvement and / or postobstructive pneumonia .