Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left basilar pneumothorax which tracks superiorly . Decreased left sided pleural effusion with mild residual . Stable mediastinal contours , left pacemaker , and clear right lung .
    OUTPUT:
    
Left basilar pneumothorax which could represent trapped lung if an underlying lesion is present . Chest CT could be obtained for further evaluation .