Introduction: Pneumomediastinum is a rare condition that occurs after physical trauma or other situations that lead to air leakage into the mediastinum. The present report describes a middle-aged patient with pneumomediastinum caused by breath-holding at work.
Case Report: A 59-year-old Japanese male presented sudden coughing immediately after breath-holding at work. A chest X-ray was normal, and a computed tomography scan showed pneumomediastinum. The patient had no other predisposing factors for pneumomediastinum, such as trauma, chronic obstructive pulmonary disease or airway infection. Bronchoscopy revealed an anatomical weakness in the bronchial wall. He recovered with two months of conservative treatment.
Conclusion: Pneumomediastinum should be considered in middle-aged patients who develop sudden coughing immediately after breath-holding. Anatomical weakness in the bronchial wall should be considered as a possible new risk factor.

Keywords: Conservative treatment, Cough, Thorax, Japan, Pneumothorax