Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The increased lucency at the left lung apex is likely due to the aerated superior segment left lower lobe . There is no pneumothorax . The appearance of the known left upper lobe mass causing central obstruction with resultant left lung volume loss is unchanged as compared to the ___ chest CT . There is a small left pleural effusion . The right lung is clear . The cardiomediastinal silhouette can not be accurately assessed .
    OUTPUT:
    
No pneumothorax . The appearance of the known left upper lobe mass is not significantly changed since ___ . Small left pleural effusion .