Congenital Lung Anomalies

CHAPTER 14 Congenital Lung Anomalies



Elizabeth A. Beierle, Mike K. Chen



Step 1: Surgical Anatomy



♦ Congenital malformations of the lungs in neonates and infants are uncommon. The three conditions most commonly encountered are discussed herein: congenital lobar emphysema, cystic adenomatoid malformations (CCAMs), and pulmonary sequestrations (both extralobar and intralobar).

♦ Many of these lesions are asymptomatic and are discovered on routine prenatal ultrasound or postnatal imaging studies. Occasionally they cause acute respiratory distress in the neonate and require immediate surgical intervention.

♦ Eventually, many CCAMs and intralobar pulmonary sequestrations become symptomatic with recurrent pneumonia, pulmonary abscess, pneumothorax, or hemoptysis, leading to the need for surgical intervention.


Step 2: Preoperative Considerations



♦ Congenital lobar emphysema is the overdistention of one or more lobes of the lung. It usually results from an absence of bronchial cartilage but may occur from mucus plugging and progressive air trapping in ventilated patients. Associated anomalies of the heart and great vessels are common.
image Infants may present with respiratory distress, diminished breath sounds, hyperresonance over the involved thorax, and evidence of mediastinal shift.

image Chest radiographs are usually diagnostic, with hyperlucency of the involved lobe, collapse or atelectasis of the other lobes, and shift of the heart toward the opposite thorax. Fig. 14-1 is a chest radiograph demonstrating overexpanded congenital lobar emphysema of the right middle lobe and significant compression of the right upper and lower lobes.

image If the infant is in severe respiratory distress, the surgeon should urgently proceed to operation; however, asymptomatic congenital lobar emphysema may regress, and observation of those infants is warranted.

♦ CCAMs derive from the abnormal branching of the immature bronchioles during lung development. They are commonly seen in the lower lobes and derive their blood supply from the pulmonary vessels; most have a communication with the tracheobronchial tree.
image CCAMs are commonly diagnosed on prenatal ultrasound. Large lesions may result in fetal nonimmune hydrops caused by compression of the mediastinum and vena cava obstruction. Spontaneous regression may occur in 40% to 80% of prenatally detected lesions.

image The most common presenting symptom is respiratory distress. Initial imaging studies include chest radiographs.

image Lesions seen on ultrasound might not be detected by plain films, and computed tomography (CT) or magnetic resonance imaging (MRI) may be helpful. Common radiologic findings include large cystic spaces in the hemithorax with mediastinal shift, or multiple cysts may be seen.

image Figures 14-2 and 14-3 are of a neonate with a congenital cystic adenomatoid malformation of the left lower lobe. The left lung is overexpanded with multiple cystic areas present. There is significant shift of the mediastinum to the right hemithorax. The stomach bubble and nasogastric tube are situated below the diaphragm, aiding in the differential diagnosis of congenital diaphragmatic hernia.

image Symptomatic neonates should undergo urgent surgical excision. Infants who remain asymptomatic should undergo elective resection at around 6 to 12 months of age to avoid the risks of neonatal anesthesia. All CCAMs that do not spontaneously involute in the first few months of life should be removed because of the risk of recurrent pneumonias and the potential for malignant transformation.

♦ Pulmonary sequestrations are cystic masses of nonfunctioning lung tissue with no connection to the tracheobronchial tree. They typically derive their blood supply from a systemic artery originating from the thoracic or abdominal aorta and may have systemic venous connection to the superior vena cava or azygos or hemiazygos veins. They exist in two forms: extralobar and intralobar. An extralobar sequestration is covered by separate visceral pleura, is completely discrete from the normal lung, and is most commonly seen in the left lower chest. Associated anomalies are common and include chest wall deformities, congential heart defects, and congenital diaphragmatic hernia.
image Neonates may be asymptomatic or have respiratory distress, pneumonia, feeding difficulties, or congestive heart failure resulting from arteriovenous shunting. Intralobar sequestrations are found within the surrounding normal lung tissue, most commonly in the left lower lobe. These also have a systemic arterial supply but commonly drain through the pulmonary veins. The most common presenting symptom in a neonate is respiratory distress.

image Initial imaging studies include chest radiographs that commonly show a left-sided lower lobe mass or consolidation. Additional imaging, including CT and MRI, may be helpful for definitive diagnosis and to outline the large systemic artery arising from the subdiaphragmatic aorta (Fig. 14-4, arrow).

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Jun 18, 2016 | Posted by in PEDIATRICS | Comments Off on Congenital Lung Anomalies

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