Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: When compared to prior , there is new dense retrocardiac and left mid lung regions of consolidation . The right lung is grossly clear . The cardiomediastinal silhouette is stable . Atherosclerotic calcifications again noted at the aortic arch . Degenerative changes seen at the shoulders .
    OUTPUT:
    
Left mid lung and basilar regions of consolidation concerning for pneumonia . Underlying effusion is also possible . Recommend repeat after treatment to document resolution to exclude underlying lesion .