Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Upright AP and lateral views of the chest provided . Suture material and mild scarring in the left upper lobe is again noted . There is atelectasis of the left lung base and the possibility a in subtle pneumonia can not be excluded . Right lung is clear . A tiny nodule projecting over the lateral right mid lung corresponds with a tiny calcified nodule on the prior CT . No large effusion is seen . No pneumothorax . Heart and mediastinal contours appear stable . Bony structures are intact .
    OUTPUT:
    
Left basal opacity most compatible with atelectasis though can not exclude an early pneumonia .