Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Correlation is made to CT torso performed at ___ earlier the same day at 5 :01 p .m . Linear opacity is again seen at the left lung base . Previously identified left - sided pneumothorax is not clearly identified on the current exam . Left lateral third rib fracture is noted . Cardiomediastinal silhouette is within normal limits . Osseous and soft tissue structures are otherwise notable for mild chronic wedging of mid thoracic vertebral bodies , similar to CT scan . Trace left - sided effusion is identified .
    OUTPUT:
    
Left lateral displaced rib fracture . Known left - sided pneumothorax at the lung base is not clearly delineated .