Laboratory Studies
Hemoglobin testing is always valuable in respiratory illness because the result is an important factor in oxygen delivery and in planning surgery, which often involves major vessels.
Renal function tests to measure BUN, serum creatinine, and electrolyte levels are important because of the frequent association of renal anomalies with pulmonary anomalies (usually pulmonary hypoplasia).
Imaging Studies
Chest radiography
Bronchogenic cysts: Bronchogenic cysts are usually fluid-filled lesions and are well circumscribed in the mediastinum. Solid masses may be difficult to differentiate from fluid. Intrapulmonic cysts appear as solitary nodules unless they contain air. Large cysts may be difficult to differentiate from macrocystic cystic adenomatoid malformation (CAM).
Pulmonary hypoplasia: In pulmonary hypoplasia, a mediastinal shift to the side of a homogenous density may be depicted, with compensatory herniation of the uninvolved lung. The associated anomalies (cardiac, skeletal, gut) may be seen.
Pulmonary sequestration: In pulmonary sequestration, an opaque or cystic lesion is seen, depending on the presence of infection.
Congenital lobar emphysema (CLE)
In congenital lobar emphysema, the involved lobe crossing the midline and the compressed normal lung can be seen. This appearance does not change during expiration or in the decubitus position. Vascularity of the involved site is attenuated. The intercostal spaces in the involved site appear widened, and the hemidiaphragm is flattened. Lucent, anteriorly herniated lung pushes the lung posteriorly, as seen on the lateral view. The lesion must be differentiated from contralateral lung hypoplasia and ipsilateral pneumothorax.
Cystic adenomatoid malformation (CAM)
Cystic adenomatoid malformation is seen as a mass of air-filled cystic spaces with mediastinal shift. In a newborn, the lung fluid may not have been absorbed, and the mass may appear fluid filled and homogenous. In an older child, pneumatoceles may be confused with cystic adenomatoid malformation. Pneumatoceles are postinfectious pulmonary cysts. They occur after Staphylococcus aureus infection. However, they are unlikely to recur in the same area of the lung as where cystic adenomatoid malformation occurs. Bronchogenic cysts are central or mediastinal (relatively early embryologic origin) and peripheral or intrapulmonary (late origin). The latter are rare (15%) and tend to be multiple. Congenital lobar emphysema is exceedingly rare in the lower lobes (< 5% of patients). It is associated with respiratory distress and mediastinal shift.
Chest computed tomography (CT) scanning
Bronchogenic cysts
In patients with bronchogenic cysts, CT findings are characteristic. The lesions are sharply marginated and nonenhancing. If the lesions are seen as soft-tissue attenuation instead of water attenuation, differentiating from lymph nodes may be difficult.
Pulmonary hypoplasia
In lung hypoplasia, loss of lung volume and associated anomalies can be seen.
Pulmonary sequestration
In pulmonary sequestration, the findings may be only an unusual solid attenuation. Therefore, CT may have little to add to sonographic and plain radiographic results unless the anomalous vascular supply can be visualized with vascular contrast enhancement.
CLE
In congenital lobar emphysema, the involved lobe and its vascularity can be easily outlined as compared to normal lung parenchyma.
CAM
Different types of cystic adenomatoid malformation can be differentiated more accurately with CT than with chest radiography. Lesions that may appear to have resolved on radiography can still be identified on the chest CT scan.
Magnetic resonance imaging (MRI)
MRI is particularly useful when delineation of blood vessels is important. It is the study of choice in difficult cases of bronchogenic cysts. The cysts appear bright on T2-weighted images and do not enhance after the administration of gadolinium-based contrast material.
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Pulmonary sequestration: MRI and magnetic resonance angiography (MRA) can be performed to identify pulmonary pathology, and aberrant systemic vessels. MRI and MRA have been suggested as the diagnostic procedures of choice for evaluating sequestration of the lung.
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Congenital lobar emphysema: In congenital lobar emphysema, MRI is used to depict the involved lung and its vascular supply.
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Cystic adenomatoid malformation: In cases of hydrops fetalis in a fetus with a prenatal, MRI may be beneficial for planning surgery. Cysts larger than 3 mm are depicted as areas of increased signal intensity on T2-weighted images.
Ultrasonography
Prenatal sonograms
Lesions on prenatal sonograms may shrink or disappear with advancing gestational age. Most pulmonary parenchymal lesions appear as echogenic fetal chest masses. The masses may be unilateral (eg, in cystic adenomatoid malformation, congenital diaphragmatic hernia, pulmonary sequestration) or bilateral (eg, in tracheal atresia). A cystic component is seen in cystic adenomatoid malformation and congenital diaphragmatic hernia (CDH) and can make differentiation of these lesions difficult.
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Pulmonary hypoplasia: In lung hypoplasia, renal malformations, oligohydramnios, decreased fetal movements in neuromuscular disease, dysmorphisms in trisomies, and skeletal dysplasias may be identified. The thoracic-to-abdomen ratio and lung area are useful parameters. Pulmonary arterial flow can be measured by using Doppler studies.
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Congenital lobar emphysema: In congenital lobar emphysema, a large fluid-filled lobe may be seen.
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Cystic adenomatoid malformation: In cystic adenomatoid malformation, a unilateral cystic mass is seen. However, the patient's postnatal clinical course and chest radiographic findings may be normal, and CT, MRI, and/or MRA may be indicated.
Echocardiography
Cardiac anomalies are associated with pulmonary hypoplasia in many patients. In addition, some cardiac malformations (eg, tetralogy of Fallot, and scimitar syndrome) may lead to pulmonary hypoplasia.
Isotope ventilation scanning
Although specific changes occur on isotope ventilation scanning, this modality seldom adds clinically useful information. In congenital lobar emphysema, decreased ventilation initially occurs, followed by isotope retention. Attenuated vascularity results in decreased perfusion. Sequestration does not fill up at all during the early pulmonary phase, but it does during the systemic (late) phase. The value of radionuclide imaging is limited because of the lack of anatomic details.
Aortography and angiography
Aortographic and angiographic findings are often definitive in sequestration and arteriovenous malformations (AVMs), yet MRI usually makes these studies unnecessary. In pulmonary hypoplasia, aortography and angiography (cardiac catherization) may be performed to evaluate for reduced pulmonary flow, aberrant pulmonary vessels, and scimitar syndrome. In pulmonary sequestration, arterial supply and venous drainage can be outlined.
Pulmonary hypoplasia
In lung hypoplasia, aortography and angiography (cardiac catheterization) may be performed to evaluate for reduced pulmonary flow, aberrant pulmonary vessels, and scimitar syndrome.
Pulmonary sequestration
In pulmonary sequestration, the arterial supply and venous drainage can be outlined. However, MRA has replaced interventional angiography as the diagnostic modality of choice for identifying sequestration vasculature in many centers.
Barium esophagraphy
This test can assist in defining mediastinal masses and blood vessels. The images also outline communication between a pulmonary sequestration and the gut. However, with the availability of CT scanning, barium esophagraphy is no longer necessary.
Other Tests
Pulmonary function tests
Residual volume, vital capacity, total lung capacity, forced expiratory volume in 1 second (FEV1), and midexpiratory flow can be used to compare volumes in selected lung lesions before and after surgical resection.
Monoclonal antibody testing
The ultimate usefulness of testing for elevated levels of cancer antigen (CA) 19-9 in intralobar sequestrations must be established.
Electrocardiography (ECG)
ECG may be performed to evaluate for associated cardiac lesions or pulmonary hypertension.
Diagnostic Procedures
Bronchoscopy
Bronchoscopy can be performed to detect airway malacia, which is present in patients with congenital lobar emphysema, abnormal bronchial branching (eg, eparterial bronchus suis, in which the right upper lobe bronchus arises directly from the trachea). The study can also be performed to detect purulent material, which indicates infection complicating a congenital malformation of the lung, or to diagnose an acquired lesion, such as bronchiectasis.
Bronchography
Bronchography is seldom indicated any longer because computed tomography (CT) scanning can demonstrate most (but not all) cases of bronchiectasis. Bronchography is useful if a bronchial anomaly is suspected. These anomalies are rare but include bronchial agenesis, which leaves a poorly aerated lobe receiving only collateral ventilation, and bridging bronchus, in which the left mainstem bronchus originates from the right side.
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Congenital Lung Malformations. The radiograph depicts an azygous fissure in the upper lobe of the right lung in a 15-year-old male. This finding is seen in up to 0.5% of the population.
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Congenital Lung Malformations. Congenital lobar emphysema on the right side of the chest in a neonate. The image shows marked lucency and hyperexpansion in the middle lobe of the right lung; this finding is consistent with lobar emphysema. The possibility of tension pneumothorax is unlikely because lung markings are seen in this region, with splaying of the pulmonary vessels. Compressive atelectasis is present in the left upper and right lower areas of the lungs. The mediastinum and heart are shifted to the left. The osseous structures are intact.
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Congenital Lung Malformations. Congenital lobar emphysema. Lateral view in the same patient as in the previous image.
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Congenital Lung Malformations. Same patient as in the previous two images. After surgery, the left lung is expanded. A thoracotomy tube is on the right, with a small right-sided pneumothorax.
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Congenital Lung Malformations. Hypovascularity of the entire left lung in a 16-year-old patient with mild exercise intolerance. This patient had hypoplasia of the left lung.
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Congenital Lung Malformations. Bronchogenic cyst. This image shows a right paratracheal mass.
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Congenital Lung Malformations. Bronchogenic cyst. These conventional radiographs demonstrate a subcarinal mass.
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Congenital Lung Malformations. Bronchogenic cyst. The computed tomograph (CT) scan demonstrates a thin-walled cyst in the right upper lobe.
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Congenital Lung Malformations. Cystic adenomatoid malformation.
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Congenital Lung Malformations. The image is an initial radiograph in a patient with congenital cystic adenomatoid malformation on the first day of life. Note the opaque lungs and a suggestion that the right lung is slightly more voluminous than the left lung.
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Congenital Lung Malformations. This radiograph was obtained in the same patient as in the previous image, on the second day of life. Note that the physiologic fluid has been resorbed and replaced with an air-containing cystic area occupying the right upper lung.
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Congenital Lung Malformations. Congenital lobar emphysema.
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Congenital Lung Malformations. The computed tomography (CT) scan shows marked hyperaeration of the left upper lobe and a mediastinal shift to the right.
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Congenital Lung Malformations. Histopathology of congenital lobar emphysema with marked overdistention of all alveoli.
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Congenital Lung Malformations. Congenital lobar emphysema in a 20-day-old patient.
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Congenital Lung Malformations. Congenital lobar emphysema in an 11-month-old patient.
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Congenital Lung Malformations. Lateral position for thoracotomy. Strap and immobilize the chest. The incision should avoid the breast tissue and scapula.
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Congenital Lung Malformations. Division of subcutaneous tissues and muscles.
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Congenital Lung Malformations. Exposure of lung tissue.
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Congenital Lung Malformations. Wound closure. After the chest drain is removed, pericostal sutures are applied.
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Congenital Lung Malformations. Closure of subcutaneous tissues and muscles in layers.
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Congenital Lung Malformations. Lesion triangulation technique. Image A: Port sites are defined to facilitate inspection and manipulation of the lesion. Image B: Trocars are inserted accordingly.
