Figure 10a. Retropharyngeal abscess with mediastinal extension in a 3-year-old boy with pharyngeal perforation caused by a pen. (a) Lateral radiograph of the neck shows widening of the prevertebral space with air in the retropharynx (arrow). (b) Anteroposterior plain radiograph of the cervicothoracic region shows bilateral widening of the upper mediastinum. Note the air in the soft tissue on the left side of the neck (arrow).