Introduction
Swyer-James syndrome is also called Swyer-James-MacLeod syndrome (SJMS) or hyperlucent lung syndrome. It is an uncommon syndrome of unilateral functional hypoplasia of the pulmonary vasculature and emphysema, with or without bronchiectasis. It is believed that SJMS is a result of childhood bronchiolitis obliterans. This condition was first described in the 1950s by respiratory physician Willam Mathieson Macleod in England, physician Paul Rober Swyer and radiologist George James in Canada. This rare lung disease is characterized by the radiographic hyperlucent appearance of a single or entire lung. Also, this condition is considered to arise from a postinfectious complication of bronchiolitis obliterans in childhood.
What Is the Etiology of Swyer-James Syndrome?
The SJM syndrome was previously considered congenital in origin, secondary to inborn pulmonary artery hypoplasia. Although the definitive cause remains uncertain, it is rarely acceptable to be a complication of childhood respiratory infections, most commonly pneumonitis or bronchiolitis obliterans. The causative agents implicated in recurrent pulmonary infections are viruses like the respiratory syncytial virus, measles, influenza A, adenovirus, paramyxovirus morbillivirus, and bacteria like Mycoplasma pneumonia, and Mycobacterium tuberculosis.
What Is the Epidemiology of Swyer-James Syndrome?
As this condition is rare, little is known about the overall incidence of Swyers-James-MacLeod syndrome. In addition, due to their diagnostic challenges, many cases remain undiagnosed or are treated as other conditions like bronchiectasis or asthma.
What Is the Pathophysiology of Swyer-James Syndrome?
SJM syndrome, also known as Bret syndrome, results from postinfectious obliterative bronchiolitis. Obliterative bronchiolitis is a clinical syndrome of small airway obstruction irreversible to bronchodilators and is triggered by an injury of the bronchiolar epithelium and the adjacent alveoli. Also, the damage during early childhood interferes with the normal development of the alveolar ducts.
What Is the Histopathology of Swyer-James Syndrome?
Histopathological studies on the SJM syndrome are scarce. However, studies of diseased lungs frequently demonstrate emphysema with cystic dilation of alveoli and dilated and constructive bronchioles. The emphysema may be of the panacinar type and include chronic inflammation and mucus plugging. The other studies reported hypoplasia of the alveoli and pulmonary arteries.
What Are the Physical Signs of Swyer-James Syndrome?
Usually, patients with SJM syndrome are asymptomatic, but some suffer from recurrent pulmonary infections. Some cases are diagnosed during childhood, while some are accidentally diagnosed during adulthood when one is undergoing investigation for some other reason. This condition can mimic other respiratory infections like respiratory conditions, pneumothorax, congenital lobar emphysema, localized pulmonary interstitial emphysema, Poland syndrome, and sequestration.
The symptomatic patients mainly present with exertional dyspnea or pulmonary infections. Other symptoms include dyspnea on exertion, wheezing, cough with or without hemoptysis, pleuritic chest pain, and reduced exercise tolerance. But most of the patients are asymptomatic.
The physical findings of SJM syndrome include hyper-resonant on percussion, decreased breath sounds, and reduced chest expansion. In addition, the apex beat may be displaced if the mediastinum is shifted to the affected site.
What Is the Diagnosis of Swyer-James Syndrome?
As this condition is rare, there are no specific guidelines for diagnostic tests. The investigations include:
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Posteroanterior Chest Radiograph - This will reveal a small hilar shadow, a reduced bronchovascular marking, and hyperlucency of the diseased lobe or segment.
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Computed Tomography (CT) - CT of the chest is performed to assess the distribution and extent of the disease. It may demonstrate bullae, emphysema, atelectasis, bronchiectasis, and scarring. It is reported that a CT chest is more sensitive than a normal radiograph.
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A Ventricular Perfusion - This test can reveal unilateral matched ventilation and perfusion defects of the diseased area.
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CT Pulmonary Angiography - This test is unnecessary but can help demonstrate hypoplasia of pulmonary vasculature in the affected lung or segment.
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Pulmonary Function Test - SJMS shows a restrictive pattern on this test.
The diagnostic criteria for SJMS require one of the following:
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Unilateral loss of lung volume.
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Unilateral loss of perfusion.
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Unilateral reduction in the vascularity on a CT scan of the chest.
What Is the Treatment for Swyer-James Syndrome?
The management of SJM syndrome is delivered using an interprofessional team approach. Prevention and prompt treatment of recurrent respiratory infections are necessary. Influenza and pneumococcal vaccinations are required. Along with that, mucolytics can also be beneficial. For sputum clearance, the chest physiotherapy techniques like postural drainage and percussion are needed. Inhaled bronchodilators and corticosteroids can also be used. Oxygen therapy can be recommended in patients with respiratory failure.
The surgical approach is necessary for patients with recurrent respiratory infections, those who fail to respond, and those whose symptoms are not covered by medical management. The surgical options are lung volume reduction surgery such as segmentectomy, lobectomy, or pneumonectomy. Lung volume reduction surgery has been successful in many patients.
What Are the Differential Diagnoses of Swyer-James Syndrome?
The conditions that mimic SJM syndrome are many, but the differential diagnosis includes both acquired as well as congenital lung disorders. They are:
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Localized pulmonary interstitial emphysema.
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Pulmonary developmental abnormalities like aplasia, hypoplasia, and pulmonary agenesis.
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Poland syndrome.
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SJMS can also be mistaken for pneumothorax.
What Is the Prognosis of Swyer-James Syndrome?
Patients with Swyer-James syndrome usually have an average life expectancy. The SJMS has a large spectrum of manifestations, including the presence and absence of bronchiectasis. The patients often suffer from mild respiratory symptoms, which improve spontaneously. People who suffer from recurrent episodes of pneumonia are at higher risk of requiring surgical intervention.
What Are the Complications of Swyer-James Syndrome?
The major complication of this syndrome is the development of bronchiectasis along with the chronic productive cough. In addition, the patients requiring surgical procedures are at risk of acquiring surgical complications such as nerve damage, pneumothorax, emphysema, infection of the surgical site, etc.
Conclusion
Swyer-James syndrome is a rare disease characterized by unilateral functional hypoplasia of the pulmonary vasculature and emphysema, with or without bronchiectasis. Although the syndrome is rare, it is often misdiagnosed or undiagnosed due to its diagnostic challenges. The physical signs of this condition may include exertional dyspnea, wheezing, cough with or without hemoptysis, pleuritic chest pain, and reduced exercise tolerance. The management of SJM syndrome is delivered using an interprofessional team approach, and lung volume reduction surgery such as segmentectomy, lobectomy, or pneumonectomy may be necessary for patients with recurrent respiratory infections.
