Diagnostic Puzzlers: The case of unresolving pneumothorax

A 25-year-old man presented to the emergency department with left scrotal swelling. He mentioned that he also had severe intermittent right-sided chest pain of 1 week's duration that began while he was lifting heavy items at work. The pain worsened with exertion and was relieved by rest. There was no radiation to the shoulder or back. The patient's medical history was otherwise not significant.

He denied diaphoresis, nausea, vomiting, fever, chills, and cough. His only associated symptoms were dyspnea and palpitations. There was no apparent chest trauma. Physical examination findings were remarkable for hyperresonance and absence of breath sounds in the left lung and swelling in the scrotum.

A chest radiograph showed hyperlucency of the left upper lung with right mediastinal shift (Figure 1). A diagnosis of left pneumothorax was made, and a chest tube was placed without lung expansion. The chest tube system was evaluated for malfunction, especially in the absence of "tidaling," or fluctuations in the water-seal chamber's fluid level. The chest tube was in good position, and no defect was found in the drainage system.

Because of the large left pneumothorax and because of the right mediastinal shift on the chest radiograph, a second chest tube was placed before the first one was pulled out. There was no lung expansion or improvement in the pneumothorax (Figure 2).

A CT scan of the chest showed multiple large left-sided bullae that had completely replaced the lung tissue of the left upper lobe and lingula. These bullae were compressing the remainder of the left lower lobe and causing a shift of the mediastinum to the right. There was also a right upper lobe bulla (3 3 3 cm). The left lower lobe remained partially collapsed even after the second chest tube placement (Figure 3).

The patient underwent bronchoscopy to rule out endobronchial airway obstruction of the left upper lung. Bronchoscopy showed a normal left main-stem bronchus as well as a normal left lower lobe bronchus with complete subsegments. There were no bronchial segments visualized in the left upper lobe or lingula.

The patient underwent left thoracotomy with resection of the large left-sided bullae. The left lower lobe was fully reexpanded into the left chest cavity (Figure 4).

What would you suspect?

The case of unresolving pneumothorax: The diagnosis is Swyer-James syndrome (SJS), also known as Swyer-James-MacLeod syndrome, MacLeod syndrome, or unilateral hyperlucent lung.

SJS was first described in a 6-year-old boy in 1953, when it was termed "unilateral pulmonary emphysema."¹ Until recently, SJS was considered a congenital disorder; however, the consensus now is that SJS is a sequela of obliterating bronchiolitis acquired in childhood as a result of adenoviral or mycoplasma infection, measles, pertussis, or tuberculosis.¹ The bronchiolitis obliterans results in air trapping and eventually in destructive tissue changes representative of bullous emphysema.^2,3

Histopathologically, SJS is characterized by submucosal and peribronchiolar fibrosis,¹ with granulation tissue plugs,⁴ as well as by destruction and obliterative scarring of the small airways.¹ Bronchiectasis can occur proximally to the obliterating bronchiolitis, although a causal relationship between the two has not been established.¹ Bronchiectasis is not a uniform finding in patients with SJS.^1,3,5,6

Because the associated illnesses usually occur in childhood, the affected part of the lung does not develop fully and the numbers of alveoli are reduced.^4,5 The pathologic process typically involves the left lung (67% to 89% of cases in select studies⁵); occasionally, both lungs may be affected.^3,5

Most patients with SJS have a history of respiratory infections, such as bronchitis or pneumonia,^1,3-6 and the presenting symptoms include wheezing, coughing, hemoptysis, and expectoration.^1,4 However, some patients may be asymptomatic, and the diagnosis is based solely on a routine chest radiograph.^1,4,5

On a chest radiograph, the involved lung or lobe appears normal or small. It also appears hyperlucent with diminished pulmonary vascular markings during inspiration.^1-6 On expiratory radiographic images, air trapping without major airway obstruction may be found.^1-6 Lung collapse may be a complication.^1,5

Radiologic and clinical findings are usually the foundations of the diagnosis. The radiographic procedure of choice is CT of the chest, with some expiratory films to better show air trapping.^1,4-6 A CT scan shows an undersized lung without central airway obstruction, as well as diminished pulmonary vasculature both medially and peripherally, with affiliated parenchymal and bronchial changes, such as a single bulla or multiple large bullae.^5,6 Bronchoscopy is usually unnecessary and can be replaced by CT in evaluating patients for SJS, but it can be done in addition to CT to establish the integrity of the main bronchial pathways^5,6 as well as to exclude other causes of air trapping, such as a tumor or foreign body.⁶

The differential diagnosis usually includes congenital lobar emphysema, bronchial atresia, and pulmonary agenesis or hypoplasia. It may not be possible to differentiate these diagnoses from SJS without pathologic examination of the resected tissue.

Management of SJS is usually supportive. Surgical resection of the affected lobe is indicated in some patients.⁷

Case and photographs courtesy of Katherine C. Rau, Ramez Sunna, MD, Sanjay Jain, MD, Maher Tabba, MD, and Rajiv Dhand, MD, of the University of Missouri Health Science Center--Columbia.

References:

REFERENCES
1. Lucaya J, Gartner S, Garcia-Pena, et al. Spectrum of manifestations of Swyer-James-MacLeod syndrome. J Comput Assist Tomogr. 1998;22:592-597.
2. Kiratli PO, Caglar M, Bozkurt MF. Unilateral absence of pulmonary perfusion in Swyer-James syndrome. Clin Nucl Med. 1999;24:706-707.
3. Ghossain MA, Achkar A, Buy JN, et al. Swyer-James syndrome documented by spiral CT angiography and high resolution inspiratory and expiratory CT: an accurate single modality exploration. J Comput Assist Tomogr. 1997;21:616-618.
4. Marti-Bonmati L, Ruiz Perales F, Catala F, et al. CT findings in Swyer-James syndrome. Radiology. 1989;172:477-480.
5. Miravitlles M, Alvarez-Castells A, Vidal R, et al. Scintigraphy, angiography and computed tomography in unilateral hyperlucent lung due to obliterative bronchiolitis. Respiration. 1994;61:324-329.
6. Moore AD, Godwin JD, Dietrich PA. Swyer-James syndrome: CT findings in eight patients. AJR. 1992;158:1211-1215.
7. Hazinski TA. Disorders causing expiratory obstruction. In: Rudolph's Pediatrics. 21st ed. New York: McGraw-Hill; 2002:23-27.