"Ring around the artery" as a presenting feature in undiagnosed asthma with pneumomediastinum

Acute bronchial asthma may be complicated by pneumomediastinum, often accompanied by the "ring around the artery" sign, described in association with asthma, trauma (gunshot wound), subclavian catheterization, and cocaine use, or with no identifiable risk factors. The diagnosis of pneumomediastinum should always be considered in an asthmatic patient with chest pain, cough, and dyspnea. Lateral chest film reveals a radiolucency outlining the right pulmonary artery. Such patients recover spontaneously with conservative therapy.