Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Diffuse interstitial abnormality in the lungs , predominantly in the upper lobes as seen on prior CT chest , is consistent with fibrosis from known sarcoidosis . Patchy opacity at the left base may represent soft tissue , however , can also be infection superimposed on chronic lung disease . Cardiomediastinal silhouette appears unchanged given differences and technique . There is no pleural effusion or pneumothorax . The osseous structures are intact .
    OUTPUT:
    
1 . Diffuse interstitial abnormality predominantly in the upper lung zones , consistent with known sarcoidosis . 2 . Opacity at the left base may be superimposed infection .