Pneumomediastinum complicates diverse disease processes, including trauma, esophageal perforation, airway injury, asthma, and mechanical ventilation. Its cause is usually readily apparent. Patients presenting with spontaneous pneumomediastinum, or Hamman's syndrome, 1 are generally evaluated with a history and physical examination, chest radiograph, and esophageal imaging. If this work-up is unrevealing, patients generally follow a benign course and no further testing is recommended
A 20-year-old woman presented to the emergency room with 2 days of pleuritic chest pain. She had just recovered from a self-limited gastrointestinal illness during which she had had bouts of emesis and retching. She did not have fever, chills, dyspnea, or trauma. She had presented several weeks earlier to an outside hospital with similar pain occurring after emesis, and she was found to have pneumomediastinum. The cause of pneumomediastinum was not found despite extensive work-up, and follow-up chest radiographs had returned to normal. Medical history was notable for mild asthma, and she reported no recent bronchodilator use or dyspnea. Last menstrual period was 2 weeks before presentation. Physical examination was within normal limits. She was comfortable and afebrile. Crepitus was not present.
Chest radiograph again demonstrated pneumomediastinum; chest computed tomography (CT) scan revealed air tracking into the left hilum and surrounding the left pulmonary artery (Fig. 1). The lung parenchyma and mediastinal structures were otherwise normal and the cause for pneumomediastinum was not identified. Gastrografin esophagram was similarly normal.
Flexible bronchoscopy revealed mucosal irregularity within the lingular bronchus without obstruction (Fig. 2). Endobronchial biopsy was diagnostic for a bronchial granular cell tumor (GCT); S-100 staining cells with granular cytoplasm were seen infiltrating the submucosa. Follow-up chest radiograph demonstrated resolution of the mediastinal air. The patient had no further bouts of emesis, and pneumomediastinum did not recur.
Surgical resection confirmed a GCT involving the lingular bronchus. The GCT did not involve the entire airway wall thickness, and no communication was evident between the tumor and the mediastinum. The lesion was limited to the submucosa and involved the lingular and left upper lobe bronchi.
High intrathoracic pressures during retching from gastroenteritis likely forced air through the GCT into the submucosa of her lingular bronchus. The air then tracked into the mediastinum causing pleuritic chest pain and the radiographic abnormalities.
Pneumomediastinum is the presence of gas in the mediastinum. Because intrathoracic pressure is negative, the gas easily tracks along tissue planes outlining mediastinal structures. The gas usually enters from the esophagus, the airway, or the lung; less commonly it originates from the oral cavity or abdomen. Esophageal perforation can occur from rupture, cancer, or instrumentation. Airway injury typically occurs from trauma or instrumentation. Asthma and mechanical ventilation cause pneumomediastinum when high alveolar pressure forces air through the submucosa of bronchioles and back into the mediastinum.
Patients with spontaneous pneumomediastinum generally have a benign course. 2 If gas ruptures into the pleural space, pneumothorax develops and could require drainage. Antibiotics are often initiated for mediastinitis until esophageal perforation is ruled out.
Two cases of pneumomediastinum associated with endobronchial lesions have been reported. One patient had an obstructing carcinoid tumor 3; the other had extensive mediastinal lymphadenopathy from Hodgkin disease eroding into the airway. 4 In both of these cases the chest radiographs and CTs suggested endobronchial disease. To my knowledge, this is the first reported case of an otherwise occult endobronchial lesion presenting with pneumomediastinum.
GCT are rare airway neoplasms, and a review of the 80 reported cases has been published. 5 The median age of presentation is in the fifth decade, but lesions have been found in young children and in the elderly. Common presenting symptoms include hemoptysis and bronchial obstruction, although many are found incidentally. One fourth of patients have multicentric lesions, and 15% of patients have concurrent skin lesions. Although bronchial GCTs are considered benign and slow-growing, GCTs in other locations might be malignant. Cases of GCT coexisting with bronchogenic carcinoma have recently been published. 6 Bronchial GCT can be treated with surgical resection or endoscopic ablation. Surgical resection is preferred for lesions larger than 8 to 10 mm to ensure negative margins. 7
Spontaneous pneumomediastinum is generally considered a self-limited condition, but it may be the first manifestation of an occult endobronchial tumor. Bronchoscopy should be considered in select cases of pneumomediastinum, especially if recurrent. GCTs are rare airway neoplasms. Surgical resection or endoscopic ablation is recommended.
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