Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single portable AP upright view of the chest was obtained . A moderate - sized pneumothorax is present on the left . There is no appreciable pneumothorax on the right . There is extensive pneumomediastinum tracking into the soft tissues of the neck . As seen on the previous CT abdomen from the same day , the free air apparently originates from the retroperitoneum . Bibasilar atelectasis is noted . There is no focal consolidation or pleural effusion .
    OUTPUT:
    
1 . Moderate left pneumothorax . 2 . Large pneumomediastinum extending into the soft tissues of the neck with gas projecting over the abdomen representing retroperitoneal source of the free air . 3 . Bilateral platelike atelectasis .