In children with asthma, routine chest X-ray typically shows bilaterally increased air volume, low diaphragms, wide diaphragmatic angles, and often a slender cardiac silhouette with a prominent pulmonic arch. Such an X-ray is not diagnostic of asthma itself, however, but rather of its complications: pneumonitis (particularly in toddlers with infectious asthma), atelectasis due to mucus obstruction, and, rarely, extra-alveolar air trapping (pneumomediastinum with or without cutaneous emphysema more often than pneumothorax). The differential diagnosis has to rule out "pseudo asthma" due to cystic fibrosis, alveolitis, achalasia, and foreign body aspiration.