A rare cause of pneumomediastinum and descending necrotizing mediastinitis: Untreated odontogenic abscess

Abstract: Pneumomediastinum is the presence of free air within the mediastinum and may be primary or secondary. Secondary pneumomediastinum typically follows trauma, invasive procedures, mechanical ventilation, or dental interventions using pressurized air; odontogenic causes without prior intervention are exceptionally rare. We report the case of a 52-year-old male with liver cirrhosis who presented with chest and neck pain 2 days after being diagnosed with a dental abscess and receiving antibiotics, with no dental procedure performed. He had fever, cervical swelling with crepitus, odynophagia, and dysphagia. Computed tomography revealed extensive subcutaneous emphysema tracking from the cervical region into the mediastinum, and inflammatory markers were elevated. He was diagnosed with secondary pneumomediastinum complicated by descending necrotizing mediastinitis and underwent mediastinal exploration and surgical drainage. Cultures grew Parvimonas micra . Postoperatively, he required intensive care and mechanical ventilation for 8 days. With culture-directed antibiotics and multidisciplinary management, he recovered fully and was discharged without sequelae. Anaerobic bacterial gas production may contribute to this rare complication. Clinicians should consider secondary pneumomediastinum in patients with chest and neck pain in the setting of odontogenic infection, even without preceding dental procedures, as early recognition, prompt imaging, surgical drainage, and definitive source control are critical for favorable outcomes.