CONGENITAL LOBAR EMPHYSEMA
This is a rare case of respiratory distress in the neonatal period. The overdistended lobe or lobes cause compression of the remaining normal ipsilateral lung and a marked shift of the mediastinum to the opposite side, so that a ventilatory crisis results with dyspnea, cyanosis, and sometimes circulatory failure.
The pathogenesis of congenital lobar emphysema falls into three categories. In the ﬁrst group, there are defects in the bronchial cartilage with absent or incomplete rings; the abnormality has also been described in chondroectodermal dysplasia or Ellis-Van Creveld syndrome. In the second group, there is an obvious mechanical cause of bronchial obstruction such as a fold of mucous membrane acting as a ball valve, an aberrant artery or ﬁbrous band, tumors, or a tenacious mucous plug. In the third and largest group, no local pathologic lesions other than overdistension of the lobe can be seen, but unrecognized bronchiolitis has been thought to be a possible cause. In each instance, the lobe inﬂates normally as the bronchus widens during inspiration, but the obstruction to it during expiration results in air trapping and overdistension.
The upper lobes are most commonly involved (80% of cases), particularly on the left side (43% of cases); the right middle lobe (32%) is second in order of frequency. Multilobar bilateral involvement rarely occurs. Differential diagnosis from endobronchial pneumothorax, diaphragmatic hernias, tension cysts, and endobronchial foreign bodies must be made.
One-third of patients are symptomatic at birth, and approximately half are symptomatic in the ﬁrst few days after birth. Affected infants may have severe respiratory symptoms and a rapid deterioration, resulting in death. Infants present with increasing dyspnea and recession; cyanosis occurs in 50% of cases and is more obvious on crying. Only 5% of patients are presented after 6 months of age. Physical examination reveals hyperresonance and bulging of the affected hemithorax with a contralateral displacement of the trachea and mediastinum. Hyperlucency of the diseased side is seen on radiography; the ribs are spread farther apart, the diaphragm is lower than normal and ﬂattened, and the uninvolved lobe or lobes may be atelectatic. There is displacement of the mediastinum to the opposite side where the lung appears relatively radiopaque, but the diaphragm is not elevated as seen in atelectasis. In the involved lung, vascular markings may distinguish the abnormality from a pneumothorax.
Lobectomy is indicated for patients who have persistent or progressive respiratory failure, and early lobectomy is required for infants who have signiﬁcant respiratory distress in the neonatal period. Patients presenting with relatively mild symptoms or diagnosed on chest radiographic examination may be treated conservatively.