Cheek Injury: A Rare Cause of Pneumomediastinum.

Pneumomediastinum is a rare condition characterized by the presence of air within the mediastinal space. It may occur spontaneously, often due to raised intrathoracic pressure, or secondarily from trauma, infection, or iatrogenic causes. Self-inflicted intraoral trauma is an exceptionally rare etiology but should be considered in recurrent or unexplained cases. A young woman with a history of depression and a chronic motor tic leading to habitual cheek biting presented with facial swelling and extensive subcutaneous emphysema after biting her right buccal mucosa. Imaging demonstrated cervicofacial emphysema extending into the deep neck spaces and upper mediastinum, consistent with pneumomediastinum. No evidence of alveolar rupture, infection, or other intrathoracic pathologies was found. A similar episode had occurred six weeks earlier, likewise attributed to cheek trauma. Apart from a large traumatic ulcer of the right buccal mucosa, no other cause, such as asthma, Valsalva-like activities, trauma, or dental procedures, was identified, making the self-inflicted injury the most likely etiology. She was observed in intensive care, remained stable, and was discharged with a nocturnal mouthguard and outpatient follow-up. This case illustrates an unusual mechanism of pneumomediastinum through direct mucosal injury and air tracking along fascial planes. Recurrent episodes highlight the behavioral component, warranting both medical and psychosocial attention. Conservative management proved effective, with prevention focusing on behavioral modification and protective measures. Unusual causes of pneumomediastinum, including self-inflicted oral trauma, must be considered. Careful history-taking, imaging, and preventive strategies enable safe management and reduce recurrence.