Abstract
Lung herniation is a rare condition that can be classified on the basis of location and etiology. We report an unusual case of right apical lung herniation presenting with dysphagia. Computed tomography of the neck demonstrated an air-containing structure in the root of the right side of the neck, related to but separate from the anteromedial aspect of the right lung apex. The diagnosis of an apical lung hernia was confirmed using high-resolution CT reconstructions. This case highlights that, although uncommon, apical lung hernias should always be considered when investigating abnormalities of swallowing. Identification of an apical lung hernia on plain chest radiographs avoids further unnecessary investigations and surgical intervention. Knowledge of their presentation may avoid complications that could arise from neck interventions such as subclavian central catheter insertion.
Introduction
Lung herniation is a rare condition that can be classified on the basis of location and etiology. We report an unusual case of right apical lung herniation presenting with dysphagia. This case highlights that, although uncommon, apical lung hernias should be considered when investigating abnormalities of swallowing.
Case Report
A 78-year-old woman presented with a history of a persistent foreign body sensation in her throat, particularly on the right side, exacerbated by swallowing. Associated with this sensation were bouts-of coughing. There was no history of the patient swallowing a foreign body. Her medical history included the excision of vocal fold polyps in 1983 and being an exsmoker. The patient's voice was hoarse but not stridorous. Physical examination of her neck was unremarkable.
After the initial consultation, a barium swallow examination was requested, which showed that the proximal esophagus was deviated to the left but was otherwise normal. This was thought to be caused by either an apical bulla or a tracheal abnormality.
Computed tomography(CT)of the neck demonstrated an air-containing structure in the root of the right side of the neck, related to but separate from the anteromedial aspect of the right lung apex (figure, A and B). The high-resolution CT reconstructions confirmed that the mass was separate from the pharynx, trachea, and esophagus (figure, C and D). The trachea was central in position, although there was minor leftward deviation of the esophagus. Little change in the size of the mass was seen on subsequent CT. The remainder of the neck was normal. Review of the patient's previous chest x-rays demonstrated a right apical lucency lying above the level of the first rib posteriorly. These appearances were consistent with a right apical lung hernia related to the anteromedial aspect of the costovertebral (Sibson) fascia.
Contrast-enhanced axial soft-tissue (
Discussion
The differential diagnosis of a paratracheal air collection includes pharyngocele, esophageal diverticulum, laryngocele, apical lung hernia, and apical paraseptal blebs, or bullae. 1
Lung herniation is rare and can be described as the protrusion of pulmonary tissue outside the thoracic cavity. 2 Morel-Lavallae described the classification of lung hernias in 1845 using, primarily, location and, secondarily, etiology. 3 The location of a lung hernia can be subdivided into cervical, chest wall, or diaphragmatic; etiology can be subdivided into congenital or acquired (spontaneous, traumatic, or pathologic). Apical (cervical) herniation is the least common location for a lung hernia to be found. 4
Lung hernias are congenital in 20 to 22% of cases and acquired in 78 to 80% of cases. 5 The majority of apical lung hernias in children are congenital and often resolve spontaneously. Apical lung hernias diagnosed in adulthood are usually acquired. Acquired causes include penetrating chest trauma or surgery, chest wall neoplasms, and chest wall infections. Apical lung herniation can be spontaneous and has also been reported in wind instrument players, patients with chronic lung disease, and weight lifters (e.g., with a history of prolonged/repeated Valsalva maneuvers). 6 In our case the patient had no relevant clinical history, and the etiology was thought to be spontaneous.
Most reported patients with apical lung herniation are asymptomatic. In a series of 6 patients described by McAdams et al, only 2 patients (33%) had symptoms from the hernia. 7 One had a cough due to tracheal irritation, and the other reported mild dysphagia, possibly caused by esophageal compression by the herniated lung. Cervical pain, which may suggest incarceration, was not described by any of the patients in the McAdams case series.
The apex of the lung is usually retained within the thorax by the muscles of the thoracic inlet, Sibson fascia, and the parietal pleura. Sibson fascia is also known as the deep cervical fascia, or suprapleural fascia, and acts like a diaphragm across the thoracic inlet, allowing the lung apex to rise above the first costosternal junction.
Sibson fascia arises from the transverse process of the C7 vertebra and inserts along the inner border and costal cartilage of the first rib. It blends with the parietal pleura and is reinforced by the scalenus minimus muscle. The posterolateral boundaries of Sibson fascia are the vertebral column, first rib, levator scapulae muscle, and scalenus medius muscle; the medial boundary is formed by the superior mediastinal structures; and the anterior boundary is formed by the scalenus anterior and sternocleidomastoid muscles. 8
There is an area of potential weakness, anteromedially, between the anterior scalenus and sternocleidomastoid muscles. It is here that apical lung hernias occur, caused by either weakening or rupture of Sibson fascia. 9
Apical lung hernias are typically identified on plain chest radiographs as apical radiolucent areas of variable size that extend into the neck. Because they are often intermittent and reducible, diagnosis can be aided by performing the chest radiograph at maximal inspiration or with the patient performing the Valsalva maneuver. It is often easier to identify an apical lung hernia on a lateral chest radiograph. 5 Barium swallow examination may show deviation of the esophagus. The finding of an air-fluid level can be used to differentiate an esophageal diverticulum from an apical lung hernia. A CT scan can show continuity between the radiolucent mass and the rest of the lung and allows identification of the exact location and size of the anatomic defect.
In conclusion, this case reminds us that, although uncommon, apical lung hernias should always be considered when investigating swallowing abnormalities. Identification of an apical lung hernia on plain chest radiographs avoids further unnecessary investigations and surgical intervention. Knowledge of their presentation may avoid complications that may arise from neck interventions such as subclavian central catheter insertion.