A 5-week-old girl was brought to the emergency department by her parents because of increased crying, irritability and stridor. Her mother had noticed a change in the character of the patient's cry, described as "hoarse." The baby wasn't drinking as much as usual and had a cough. She did not have fever or history of apnea or cyanosis. The child was born full term by normal spontaneous vaginal delivery with no complications.
Physical examination demonstrated a well-developed, crying infant. She was afebrile, heart rate 150, respiratory rate 52, and oxygen saturation of 93%. Growth parameters were normal. The lungs were clear to auscultation; cardiac examination was normal. Airway and chest radiographs were obtained. The findings prompted further evaluation by computed tomography (CT) of the thorax.
Anterioposterior chest radiograph showed hyperaeration of the right upper lobe with herniation across the midline. A leftward mediastinal shift, atelectasis of the right lower lobe, and slight widening of the interspaces of the ribs on the right were seen. CT of the thorax with lung windows confirmed an enlarged, hyperaerated right upper lobe with compressive atelectasis of the right lower lobe, as well as thinning and spreading of the pulmonary vasculature. Mediastinal shift and decreased volume of the left hemithorax were evident. No aberrant vessel or extrabronchial lesion was seen.
Figure 1. Anteroposterior chest radiograph demonstrates hyperaeration of the right upper lobe with herniation across the midline (arrows). Leftward mediastinal shift, atelectasis of the right lower lobe, and slight widening of the interspaces of the ribs on the right are also shown.
Figure 2. CT of the thorax with lung windows confirms an enlarged, hyperaerated right upper lobe with compressive atelectasis of the right lower lobe (arrows). There are thinning and spreading of the pulmonary vasculature. Mediastinal shift and decreased volume of the left hemithorax are evident. No aberrant vessel or extrabronchial lesion is seen.
Congenital lobar emphysema
Unilateral, hyperlucent, enlarged lung volume in a newborn patient with no history of previous intubation indicates one of a few diagnoses: congenital lobar emphysema (CLE), cystic adenomatoid malformation, congenital or acquired lung cyst, or pneumothorax. CLE usually can be distinguished readily from these other entities. CLE is a symptom complex that results from progressive hyperinflation, usually involving only one lobe of the lung, as air enters during inspiration and is trapped by a ball-valve mechanism on expiration. Lesions that can result in CLE can be categorized as intrinsic (eg, hypoplastic bronchial cartilages, kinked bronchus, bronchial tumors) or extrinsic bronchial obstruction. Extrinsic causes can be further characterized as cardiovascular (eg, patent ductus arteriosus, hypertensive dilated pulmonary arteries) or noncardiovascular obstructing lesions (eg, bronchogenic cyst, esophageal duplication cyst, mediastinal adenopathy, mediastinal tumor or accessory diaphragm).1
CLE most often is unilobular and occurs in the left upper lobe (40%), right middle lobe (30%), or right upper lobe (20%). Early in its course, the lobe may appear opaque radiographically due to retained fetal fluid. Over time, the fluid is removed through the lymphatics and capillaries as air moves in by collateral air drift CLE accounts for 10% to 15% of congenital lung masses, occurring more commonly in boys than in girls.2
The diagnostic evaluation of a child whose chest radiograph suggests CLE typically includes contrast-enhanced CT to define the bronchial anatomy and vascular structures (assessing for vascular rings or aberrant vessels) and to exclude extrabronchial obstructing lesions. Echocardiogram also is indicated because associated cardiovascular anomalies occur in 12% to 14% of patients.2
The treatment of CLE depends upon the severity of respiratory distress. In the majority of cases, the patient will undergo surgical resection of the affected lobe.3 Observational management can be considered if the infant only has mild respiratory distress or if the CLE is an incidental finding in an asymptomatic patient. As the child grows, the lesion generally stays similar in size, while the remaining lung tissue grows at the normal rate. No increased incidence of infection has been noted.
1. Kuhn J, Slovis T, Haller J. Caffey's Pediatric Diagnostic Imaging. 10th ed. Philadelphia, PA: Elsevier, 2004.
2. Berrocal T, Madrid C, Novo S, et al. Congenital anomalies of the trachee - bronchial tree, lung, and mediastinum: embryology, radiology, and pathology. Radiographies. 2004;24(l):el7.
3. Paterson A. Imaging evaluation of congenital lung abnormalities in infants and children. Radiol Clin North Am. 2005 Mar,43(2):303-323.