Cervical herniation of an atypical emphysematous bulla

A 68-year-old man with a hard lump on his palate was admitted for further evaluation. During the preoperative assessment, an emphysematous bulla was incidentally detected.

Chest X-Ray (Figure 1) performed for routine pre-operative evaluation showed a cystic lesion occupying most of the right apical region. These findings were confirmed on a CT scan (Figure 2) which showed Para-septal emphysema with apical predominance (Right > Left) and a large thin-walled air-containing bulla arising from the right apical lobe extending into the neck space. The large bulla caused mild deviation of the trachea to the left and displacement of the right carotid sheath and its content. There was also passive atelectasis of underlying apical lung parenchyma. The patient had a surgical procedure to remove the hard palate mass and received the appropriate anaesthetic management for an individual with large emphysematous bullae.

A bulla is defined as an air-filled region within the lung that is larger than 1 cm in diameter and has developed as a result of emphysematous deterioration of the lung parenchyma. [1] They do not participate in gas exchange and are most frequently found in the hypo-perfused upper lungs. Pulmonary bullae frequently coexist with severe emphysema but can rarely be seen in the healthy lung. The apex of the lung extends into the base of the neck three to four centimetres above the level of the first costal cartilage, allowing such bullae to herniate into the neck from the thoracic cavity. [2]

A bulla from the lung's apex has been theorised as having a chance to herniate through the Sibson fascia and appear in the neck. [3] Sibson's fascia has a potential weakness on the anteromedial side between the scalenus anterior and sternocleidomastoid muscles. [2,4] There are a few hypotheses about bulla expansion. The most widely accepted explanation states that a one-way valve mechanism results from partial occlusion of the airways in an emphysematous lung, allowing air to enter the bulla during inspiration but become trapped during expiration, slowly leading the bulla to enlarge. [3]

Enlarged bullae may result in mediastinal displacement, atelectasis, and compression of the nearby lung parenchyma. Bullae enlargement are common, although spontaneous regression is unusual. [3]

A few major complications due to emphysematous bullae include haemorrhage into the bullae, infection, and spontaneous pneumothorax. [3,5–7]. Patients with concomitant bullous lung lesions may present for non-thoracic surgery. The diagnosis of this condition is crucial since these patients are more likely to have complications from the bullae or underlying lung disease while under anaesthesia. [8]

Bullae are easily identifiable on a typical chest x-ray. The precise anatomical location, volume occupied, condition of the underlying lung parenchyma, and presence of complicated characteristics like infection and pneumothorax can all be determined with the aid of a CT scan. [9] Few cases of emphysematous bullae herniation have been reported in the literature, making it a relatively unusual complication.

In this case, the patient had a significant history of cigarette smoking for the past 30 years. The patient underwent an excisional biopsy for the palatine mass which turned out to be a lipoma. Due to the presence of a large emphysematous bulla and extreme age, the biopsy was performed using IV sedation. General anaesthesia was avoided because anaesthesia induction and positive-pressure ventilation could lead to the rupture of these bullae and lead to potential life-threatening pneumothorax. Therefore it’s crucial for a radiologist to point out such imaging findings.

Written informed patient consent for publication has been obtained.