Pediatrics

Congenital Lobar Emphysema

OVERVIEW: What every practitioner needs to know Are you sure your patient has congenital lobar emphysema? What are the typical findings for this disease?

Congenital lobar emphysema (CLE) represents an uncommon but clinically important congenital lung anomaly. It is characterized radiographically and pathologically by progressive hyperinflation of a pulmonary lobe. Most patients present with symptoms during the newborn period. The vast majority of lesions are diagnosed when the patient is less than 6 months of age. The left upper lobe is most commonly affected, followed in frequency by the right middle lobe and right upper lobe.

The most common symptoms and signs follow:

Tachypnea

Dyspnea

Emphysematous lobes visualized on chest radiograph

Additional Associated Symptoms and Signs

Additional symptoms may be encountered in a patient presenting with CLE and may include cough, wheezing, and/or hoarseness. These symptoms are highly variable and are dependent on the location and severity of airflow obstruction.

Physical examination findings may include wheezing, prolongation of the expiratory phase, and/or decreased breath sounds (on the affected side).

In laboratory analysis, variable degrees of hypoxia or hypercarbia may be evident.

Epidemiology of Congenital Lobar Emphysema

CLE is an uncommon congenital anomaly, occurring in 1/20,000-30,000 deliveries. Despite the prevalence of current ultrasonographic prenatal imaging, the majority of cases are diagnosed postnatally. The prevalence of this anomaly during pregnancy is unknown. The most common presentation is in the neonatal period, with a diagnosis at birth occurring in approximately 25% and a diagnosis by 1 month of age in approximately 50% of cases. The diagnosis of CLE is sporadic and rare after the age of 6 months.

Based on the age of diagnosis, Myers described three types of CLE. In this classification scheme, type I occurs in infants, type II in older children and type III is defined as an incidental finding in asymptomatic patients. Although both type II and type III cases have been identified, they are thought to be rare.

Patients who require surgical management for CLE are generally of a younger age at diagnosis. An association with other congenital anomalies is not uncommon. A comorbid cardiac anomaly is present in 12%-20% of cases. Less common but reported associations include those of the renal, musculoskeletal, and cutaneous systems.

CLE is more common in male patients. The anomaly does not have a familial pattern but does occur primarily in whites.

What other disease/condition shares some of these symptoms?

CLE belongs to a group of nonvascular pulmonary lesions. In this group of congenital anomalies, the formation of the lung is abnormal, but the associated vasculature is normal. Other nonvascular pulmonary malformations include congenital bronchial atresia, bronchogenic cyst, and congenital pulmonary adenomatoid malformation and the following:

Bronchogenic cyst

Congenital bronchial atresia (a rare cause of CLE)

Congenital cystic adenomatoid malformation/congenital pulmonary airway malformation

Pneumothorax

Lung cyst

Bronchopulmonary sequestration

Congenital diaphragmatic hernia

Foreign body aspiration

Interstitial lung disease

Congenital pulmonary lymphangiectasis (rare)

What caused this disease to develop at this time?

The mechanism of CLE consists of progressive pulmonary lobar hyperinflation. Overdistention of lung units generally occurs because of a "ball valve" obstruction at the bronchial level; by this mechanism, more air is allowed to enter the affected lobe on inspiration than is allowed to egress from the lobe on expiration. The total number of alveoli within the affected lobe is variable but may be normal. Airway structure and arterial blood supply are generally normal for age in size and structure. Alveolar walls are structurally normal within the lesion, but alveolar units are consistently overdistended.

The left upper lobe (~42%) is the most commonly affected area in CLS. It is also commonly seen in the right middle lobe (~35%) and right upper lobe (~21%). The lower lobes are infrequently affected (~0.9% each).

The cause of CLE is unknown in approximately half of documented cases; in these instances, the bronchus appears anatomically normal, and no offending obstructive lesion can be found. In 25% of cases, CLE may be attributed to a congenital defect of cartilage. Here, dysplastic bronchial cartilage leads to bronchomalacia, with resultant airway obstruction and air trapping. In the remaining 25% of cases, CLE is due to bronchial obstruction. Obstruction may be endobronchial (inspissated mucus or tissue infolding/proliferation) or due to external compression (vascular ring, mediastinal mass, bronchogenic cyst) or a diffuse bronchial pathologic condition (tuberculosis, cytomegalovirus).

Bronchial Atresia as a rare cause of Congenital Lobar Emphysema

Bronchial atresia is a rare cause of CLE, as involvement of a lobar bronchus is a relatively unusual finding. Bronchial atresia may be congenital or acquired.

In congenital bronchial atresia, the most commonly affected bronchus is that supplying the left upper lobe. The defect is postulated to be secondary to developmental abnormalities in bronchial cartilage or, alternatively, to a localized interruption of blood flow to a bronchus. Postnatally acquired atresia may be related to the postinflammatory change associated with trauma or infection. In the case of lobar involvement, the affected emphysematous lobe is typically very large, with adjacent normal lung tissue being compressed and mediastinal shift being a commonly associated finding. Herniation of the enlarged lobe across the anterior mediastinum into the contralateral side of the chest may be visualized on radiographic imaging.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

There are no laboratory studies that are specific or sensitive for the diagnosis of CLE.

Would imaging studies be helpful? If so, which ones?

Imaging Studies: Prenatal Imaging

Prenatal Ultrasonography

The routine use of prenatal ultrasonography has allowed for earlier identification of many congenital lung lesions

Ultrasonographic examinations carry no risk of radiation exposure to mother or fetus, and serial examinations may be safely performed to evaluate for changes in quality or growth of the lesion.

In the prenatal period, CLE may appear as a bright echogenic mass as a results of the presence of fetal lung fluid. Other findings on ultrasonography may include cystic regions, mediastinal shift, and compression of contralateral lung tissue.

Because of these relatively nonspecific findings, differentiation of CLE from other congenital lung lesions, including microcystic congenital airway malformation, may be challenging.

Over time and with repeated imaging, spontaneous regression in the size and changes in the quality of the lesion are commonly seen. These changes may ultimately result in an inability to successfully distinguish the congenital anomaly from normal surrounding lung tissue. Alternatively, a progressive increase in the size of the anomaly may also be visualized; growth of the lesion and associated mediastinal shift may create abnormalities in fetal blood flow as well as hydrops fetalis and polyhydramnios. The finding of hydrops fetalis on ultrasonography represents a major negative antenatal prognostic factor.

Prenatal Ultrafast Magnetic Resonance Imaging

With the use of magnetic resonance imaging (MRI), radiation exposure to mother and fetus is avoided. Prenatal ultrafast MRI offers a potential adjunctive study to prenatal ultrasonography when further imaging sensitivity is desired. Additional diagnostic clarity may be provided with improved ability to differentiate between common causes of fetal lung echogenicity.

When a prenatal imaging study has revealed a congenital lung lesion, postnatal follow-up imaging is mandatory. Even if undetectable on third-trimester imaging, pulmonary lesions have the potential to cause severe respiratory compromise in the neonatal period. Symptoms may arise from direct mass effect and airway compression or from pulmonary hypoplasia resulting from chronic prenatal compression of the developing lung tissue.

Because of the potential for neonatal respiratory failure, delivery of the infant should be planned at a center capable of managing respiratory emergencies. Even if not significantly symptomatic at birth, the infant may benefit from a longer than usual stay in the neonatal nursery so that he/she can be observed for symptoms or signs of respiratory compromise. Further evaluations for cardiac anomalies may also be considered given the association of congenital cardiac defects with CLE.

Imaging Studies: Postnatal Imaging

Chest Radiography of the Chest

On a neonatal radiograph of a child with CLE ( Figure 1), the affected lobe may be homogeneously opaque because of retained fetal lung fluid. Alternatively, the radiograph may reveal a diffuse reticular pattern caused by distention of the pulmonary lymphatic vessels. Later, as fluid is absorbed, the affected area will become filled with air and be hyperlucent.

Figure 1.

Radiograph of congenital lobar emphysema.

Hyperinflation of the segment or lobe affected is seen in all affected individuals

Other radiographic findings may be visualized and may include the following:

Ipsilateral and contralateral atelectasis or volume loss

Attenuated bronchovascular markings in the affected lobe

Spreading of ipsilateral ribs

Flattening of diaphragm

Mediastinal shift

Computed Tomography of the Chest

All findings on radiography can be further characterized with the use of computed tomography (CT) (Figure 2). CT with three-dimensional reconstruction is often indicated for confirmation of the lesion, further anatomic characterization, and surgical planning. An intravenous contrast study is indicated to confirm the absence of an aberrant systemic blood supply and thereby make an alternative diagnosis of pulmonary sequestration unlikely.

Figure 2.

Chest CT of congenital lobar emphysema.

Early on in the neonatal course, CT may simply show hyperinflation of a segment or lobe with thickening of interlobular septa and ground glass opacities. This can be readily confused with interstitial lung disease. Because of the potential for this early diagnostic confusion, CT may be best used and interpreted after resorption of fetal lung fluid, presuming that the stability of the infant will allow a delay in diagnostic imaging.

Risks associated with CT imaging include radiation exposure. In addition, conscious sedation will generally be required for children undergoing CT imaging, and anesthetic risks may apply.

Scintigraphy

A ventilation-perfusion scan will reveal decreased perfusion in the affected lobe of a patient with CLE.

If you are able to confirm that the patient has congenital lobar emphysema, what treatment should be initiated?

Intrapartum thoracoamniotic shunting is an option for large lesions and lesions that threaten fetal viability.

After delivery of the infant, resuscitative efforts may be required. During resuscitation with larger and more symptomatic lesions, positive pressure ventilation may result in worsening of air trapping; tension emphysema of the affected lobe and vascular compromise are potential complications. Options during resuscitation include high-frequency ventilation, selective bronchial intubation, or endoscopic decompression of the emphysematous lobe.

Bronchoscopic visualization of the affected bronchus is warranted to evaluate for malacia, compression, and other causes of obstruction.

After stabilization of the infant has been achieved, resection of the affected lobe has been the traditional and standard recommendation for postnatal management. Recently, there has been a postulated role for conservative management. Surgical resection of the affected lobe has been recommended in all infants less than 2 months of age and in those greater than 2 months of age with severe respiratory symptoms. Conservative treatment with close follow-up may be considered in infants greater than 2 months of age with mild to moderate respiratory symptoms and normal bronchoscopic findings.

What are the adverse effects associated with each treatment option?

Disadvantages of Surgery

Lobectomy is associated with a chronic decrease in lung volume, despite some compensatory growth of remaining lung tissue. In addition, some patients with CLE may show clinical and radiographic improvement with time; it is not known whether these cases represent some reversibility of the disease process or, alternatively, overgrowth of normal lung and compensation for the nonfunctional and emphysematous lobe. Of note, in long-term follow-up studies, outcomes have been shown to be similar in conservative and surgical treatment groups.

Advantages of Surgery

Any patient, including those with initially minimal symptoms, can deteriorate and present with life-threatening symptoms with rapid growth of the lesion. Although not possible in all cases, the increasing use and applicability of the minimally invasive thoracoscopic approach offers less morbidity compared with open chest surgery. In addition, pleuropulmonary blastoma represents just less than 1% of all primary pediatric malignant lung tumors but has been reported in association with a previously asymptomatic CLE that was noted incidentally on radiography and was removed because of increasing size.

What are the possible outcomes of congenital lobar emphysema?

The fetal complications of CLE include fetal compromise requiring fetal intervention. Fetal compromise may also cause hydrops fetalis and fetal death. Postnatal complications include life-threatening respiratory compromise or failure requiring early support and surgical intervention.

Regression in the size of CLE lesions and improvement in symptoms with conservative treatment have been documented.

Lastly, initial regression in the size of a lesion with minimal clinical symptoms may be seen, only to be followed by growth of the lesion and progressive symptoms necessitating surgical removal.

What is the evidence?

Chao, MC, Karamzadeh, AM, Ahuja, G. "Congenital lobar emphysema: an otolaryngologic perspective". Int J Pediatr Otorhinolaryngol. vol. 69. 2005. pp. 549-54.

(A review of the diagnostic approach to CLE from the otolaryngologist's perspective. The roles of bronchoscopy and imaging are included.)

Horak, E, Bodner, J, Gassner, I. "Congenital cystic lung disease: diagnostic and therapeutic considerations". Clin Pediatr. vol. 42. 2003. pp. 251-61.

(Highlights clinical case reports, pathologic considerations, and diagnostic and treatment options for the congenital cystic lung disorders.)

Berrocal, T, Madrid, C, Novo, S. "Congenital anomalies of the tracheobronchial tree, lung and mediastinum: embryology, radiology and pathology". Radiographics. vol. 24. 2004. pp. e17.

(A comprehensive review of the embryologic origins, pathologic mechanisms, and clinical and radiographic features of various congenital anomalies affecting the airway, mediastinum, and pulmonary parenchyma.)

Olutoye, OO, Coleman, BG, Hubbard, AM. "Prenatal diagnosis and management of congenital lobar emphysema". J Pediatr Surg. vol. 35. 2000. pp. 792-5.

(Case reports representing the prenatal and immediate postnatal course of CLE. Considerations in neonatal management are included.)

Karnak, I, Senocak, E, Ceftci, AO. "Congenital lobar emphysema: diagnostic and therapeutic considerations". J Pediat Surg. vol. 34. 1999. pp. 1347-51.

(Retrospective review of patients with CLE. Diagostic and therapeutic approach to the patient with CLE.)

Mei-Zahav, M, Konen, O, Manson, D. "Is congenital lobar emphysema a surgical disease?". J Pediatr Surg. vol. 41. 2006. pp. 1058-61.

(Retrospective review of outcomes in patients treated surgically and conservatively for CLE.)

Walsh, S, Wood, AE, Greally, P. "Pleuropulmonary blastoma type I following resection of incidentally found congenital lobar emphysema". Ir Med J. vol. 102. 2009. pp. 230.

(Individual case report of patient with pleuropulmonary blastoma diagnosed after growth of CLE noted incidentally .)

Ozelik, U, Gocmen, A, Kiper, N. "Congenital lobar emphysema: evaluation and long term follow up of thirty cases at a single center". Pediatr Pulmonol. vol. 35. 2003. pp. 384-91.

(Retrospective review of patients with CLE. Includes clinicopathologic correlation.)

Ankermann, T, Oppermann, HC, Engler, S. "Congenital masses of the lung, cystic adenomatoid malformation versus congenital lobar emphysema: postnatal diagnosis and implications for postnatal treatment". J Ultrasound Med. vol. 23. 2004. pp. 1379-84.

Guide to the diagnosis of congenital pulmonary lesions with special consideration given to the differentiation of CLE from congenital pulmonary artery malformation.)

Seo, R, Ando, H, Kaneko, K. "Two cases of prenatally diagnosed congenital lobar emphysema caused by lobar bronchial atresia". J Pediatr Surg. vol. 41. 2006. pp. E17-20.

(Review of a case report of CLE resulting from lobar bronchial atresia.)

Lee, EY, Boiselle, PM, Cleveland, RH. "Multidetector CT evaluation of congenital lung anomalies". Radiology. vol. 247. 2008. pp. 632-48.

(Outlines the role of CT imaging in patients with CLE and other congenital lung anomalies.)

Ongoing controversies regarding etiology, diagnosis, treatment

The primary controversy is regarding surgical versus conservative management, as outlined above.

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