Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Diffuse interstitial markings are noted , right greater than left . Additionally , there is a right upper lobe opacity with mediastinal shift towards the right . This is suggestive of underlying volume loss , possibly prior lobectomy changes . However , if there is no history of surgery , underlying malignancy should be considered . Superimposed post-obstructive pneumonia is possible . Atelectasis is noted at the left lung base . No substantial pleural effusion . Cardiomediastinal silhouette is within normal limits . No acute osseous abnormalities identified .
    OUTPUT:
    
Right upper lobe opacity and volume loss . While this may reflect prior lobectomy change , there may be an underlying mass with possible post-obstructive pneumonia , and should be further investigated with CT .