AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Background

Congenital lobar emphysema (CLE) is a potentially reversible though possibly life-threatening cause of respiratory distress in the neonate. CLE presents with overexpansion of a pulmonary lobe and resultant compression of the remaining ipsilateral lung. A mediastinal shift away from the increased-volume lung can also compress the contralateral lung. The abnormality is related to intrinsic bronchial narrowing. In these cases, there is weakened or absent bronchial cartilage, so that there is inspiratory air entry but collapse of the narrow bronchial lumen during expiration. This bronchial defect results in lobar air trapping. In the case of congenital extrinsic compression, such as by a large pulmonary artery, affected cartilage rings are malformed, soft, and collapsible in response to the long-term in utero extrinsic effect.

Emergency surgical lobectomy was once considered the only treatment for CLE, but appropriate care may be nonsurgical in infants with only moderate respiratory distress. Maintaining ventilatory pressures and volume as low as possible avoids producing ventilator-related hyperexpansion of an affected lobe. Management by more conservative, gentle ventilation technique is often successful. Fewer surgeries result, because after diagnosis and initial treatment, the affected lobe only occasionally continues to expand. Infants with CLE who are not clinically in respiratory distress and who are able to feed and grow do not necessarily need surgery. Lobar emphysema can occur in hypoalveolar (fewer than expected number of alveoli) and polyalveolar (more than expected number of alveoli) forms.

Pathophysiology

Overdistention of the airspaces within a pulmonary lobe is associated with air trapping and compressive changes in the remainder of the lung (see Image 3, Image 8). A mediastinal shift away from the increased volume results in compression of the contralateral lung.

CLE almost always involves one lobe, with rates of occurrence as follows:

• Left upper lobe - 41%
• Right middle lobe - 34%
• Right upper lobe - 21%

CLE presents in the newborn period with a fluid-filled, overdistended lobe. The diagnosis can be made in utero or shortly after birth. CLE has an unexplained cause in some patients. In many patients, the absence or hypoplasia of cartilage rings of major and branch bronchi, with resultant bronchial collapse (bronchomalacia) during expiration, creates air trapping, resulting in CLE; however, in some patients the cause is unknown. Other possible causes of CLE are intrinsic parenchymal elastin defect and fibrosis of the interstitium, such that normal expiration and reduction of lobar volume cannot occur.

CLE has 2 forms:

• Hypoalveolar (fewer than expected number of alveoli)
• Polyalveolar (greater than expected number of alveoli)

Approximately 10% of patients have associated anomalies, primarily congenital heart disease. Pulmonary arteries are normal in patients with CLE.

Frequency

United States

Anomaly is infrequent and usually presents at birth. Lobar distention can be visible during in utero ultrasound as an overinflated, fluid-filled lobe; in less severe cases, the diagnosis is made in infancy or childhood.

Mortality/Morbidity

Extreme lobar overdistention is life-threatening.

• Emergency lobectomy may be required if the lobe cannot be decompressed by selective intubation of the opposite side or by placing the infant in the decubitus position with the involved lobe dependent.
• In severely affected patients, the lung is overinflated and will immediately herniate through the surgical incision.
• Less severely affected patients are managed conservatively with gentle ventilation and monitoring to ensure that respiratory status does not worsen.

Age

CLE is most often detected in neonates or identified during in utero ultrasound; however, less severely affected patients may present in infancy or childhood.

Anatomy

A single lobe usually is involved; however, patients can show multiple lobar involvement. Microscopically, cartilage plates in the bronchi are absent at the level where cartilage is expected. Identify the level at which the bronchus was resected to determine inappropriate cartilage development.

Clinical Details

The physician may observe subtle or obvious respiratory distress in an otherwise normal infant. He or she may observe asymmetry of chest and abdominal retractions on inspiration. Hypoxemia (in severely affected patients) may occur.

The thorax on the involved side is hyperresonant with decreased or absent breath sounds and transillumination. The diagnosis is often suspected upon in utero sonography if an overexpanded lobe filled with fluid is identified. Progressive respiratory distress from birth reflects the degree of emphysema; symptoms are at their worst in the first month. Occasionally, patients present in later childhood or adulthood.

Differentiate CLE (ie, congenital lesion) from Swyer-James syndrome (ie, acquired pulmonary abnormality secondary to infection). In Swyer-James syndrome, infection results in the following:

• Vascular compromise
• "Pruning" of peripheral pulmonary vasculature
• Small but hyperlucent lung (as the opposite, normal lung grows, the involved lung does not grow and appears more radiolucent)

Preferred Examination

Radiography of the chest in anteroposterior and lateral projections identifies the involved lobe, the degree of involvement, and the effect on surrounding structures. If a decubitus position radiograph is obtained, the involved lung does not collapse.

Computed tomography scanning can provide details about the involved lobe and its vascularity, as well as information about the remaining lung.

Magnetic resonance imaging can be used as an adjunct to identify vascular supply and distribution to the involved lung.

DIFFERENTIALS

Section 3 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Other Problems to be Considered

Bronchial mucous plug with associated hyperaeration
Extrinsic bronchial compression
Agenesis/hypogenesis of contralateral lung
Bronchial hypoplasia with air trapping peripherally
Congenital cystic adenomatoid malformation
Pneumothorax

RADIOGRAPH

Section 4 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Findings

A large, hyperlucent lung with attenuated but defined vascularity is observed. Compression of the remaining lung on that side, flattened hemidiaphragm, and widened intercostal spaces also are seen. An involved lung is seen herniated across the anterior midline (see Image 1, Image 4, Image 9).

On a lateral view, the heart is displaced posteriorly with retrosternal lucency representing an anteriorly herniated lobe (see Image 5, Image 10).

The lobe is unchanged during exhalation or after placing the patient in the ipsilateral decubitus position.

Chest fluoroscopy shows fixed lung and hemidiaphragm on the involved side.

Degree of Confidence

Radiographic appearance is characteristic of CLE and usually is not suggestive of other diagnoses.

False Positives/Negatives

Be certain a mucous plug is not present, which can obstruct a bronchus, creating a "check valve" phenomenon that partially obstructs an airway.

Similarly, extrinsic masses, such as a congenitally large pulmonary artery (as in the absence of the pulmonary valve), can create emphysema from partial bronchial obstruction.

Usually, with careful image analysis, cystic lung disease does not mimic CLE; however, hypoplasia or agenesis of the contralateral lung may result in marked compensatory hyperexpansion of the lung, which can closely resemble CLE.

CT SCAN

Section 5 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Findings

CT scan shows a hyperlucent, hyperexpanded lobe (attenuated but intact pattern of organized vascularity) with midline substernal lobar herniation and compression of the remaining lung. Usually, the mediastinum is significantly shifted away from the side of the abnormal lobe (see Image 2, Image 6).

MRI

Section 6 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Findings

MRI can be used to evaluate vascular supply to the involved lobe but is not routinely employed. In CLE, the abnormal lobe usually has a normal vascular supply.

ULTRASOUND

Section 7 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Findings

In utero sonography may show a large, fluid-filled lobe; mediastinal herniation can be seen. A prenatal diagnosis of CLE is not made as frequently as in other intrapleural fetal masses.

False Positives/Negatives

Variants include other causes of uneven lung expansion. In the neonate, a large pulmonary artery or mediastinal mass can compress the bronchus with overinflation of a lobe. Even the presence of a bronchial mucus plug can result in overinflation of a lobe. Infants with bronchopulmonary dysplasia often have uneven inflation of the pulmonary lobes related to bronchial cellular plugs or bronchial fibrosis, rendering the bronchus noncompliant.

NUCLEAR MEDICINE

Section 8 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Findings

Ventilation-perfusion scanning demonstrates characteristic results. Ventilation is initially diminished in the affected lobe, but ultimately, isotope retention is seen because of delayed emptying of alveoli in the emphysematous lobe. The markedly attenuated vascularity of the involved lobe results in decreased perfusion of the enlarged lobe (see Image 7).

INTERVENTION

Section 9 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Do not mistake CLE for a tension pneumothorax. Placement of a chest tube could result in lung puncture and bronchopleural fistula or persistent air leak.

Medical/Legal Pitfalls

• Failure to schedule regular follow-up visits to ensure that pulmonary status does not worsen (if the decision is made to monitor CLE).
• Failure to carefully follow up with children with lower respiratory infection. This is important, as repeated infection may cause damage in an already overexpanded lobe of the lung.
• Failure to inform parents of the presence and potential complications of CLE. The presenting lobe may be the worst of a group of malacic bronchi, so even after definitive surgery, some children may continue with wheezing and prolonged expiratory phase with symptomatic additional small airway disease.

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

Media file 1:  A frontal radiograph of the chest in a neonate shows marked overdistention of the left upper lobe with mediastinal shift to the right.
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Media file 2:  Computed tomography scan of the patient shows marked hyperaeration of the left upper lobe and mediastinal shift to the right.
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Media file 3:  Histopathology of congenital lobar emphysema with marked overdistention of all alveoli.
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Media file 4:  Anteroposterior chest radiograph shows overexpansion of the right middle lobe in a patient aged 18 months with suspected asthma.
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Media file 5:  Lateral chest radiograph shows anterior herniation of the right middle lobe.
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Media file 6:  Computed tomography scan indicates moderate hyperaeration of the right middle lobe.
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Media type:  CT

Media file 7:  Perfusion scan in right posterior oblique (RPO) projection shows virtually no perfusion of the right middle lobe.
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Media file 8:  Resected lobe is overexpanded and shows no other intrinsic abnormality.
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Media file 9:  Two-year-old patient with respiratory distress shows left upper lobe hyperaeration.
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Media type:  X-RAY

Media file 10:  Lateral chest radiograph with mild midline herniation of the left upper lobe.
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REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Intervention
• Multimedia
• References

• Congenital Lobar Emphysema. Virtual Children's Hospital, University of Iowa. http://indy.radiology.uiowa.edu/Providers. May 13, 1998.
• Doull IJ, Connett GJ, Warner JO. Bronchoscopic appearances of congenital lobar emphysema. Pediatr Pulmonol. Mar 1996;21(3):195-7. [Medline].
• Koontz CS, Oliva V, Gow KW, Wulkan ML. Video-assisted thoracoscopic surgical excision of cystic lung disease in children. J Pediatr Surg. May 2005;40(5):835-7. [Medline].
• Lacy DE, Shaw NJ, Pilling DW, Walkinshaw S. Outcome of congenital lung abnormalities detected antenatally. Acta Paediatr. Apr 1999;88(4):454-8. [Medline].
• Schwartz MZ, Ramachandran P. Congenital malformations of the lung and mediastinum--a quarter century of experience from a single institution. J Pediatr Surg. Jan 1997;32(1):44-7. [Medline].

Article Last Updated: Oct 26, 2006