Congenital Disorders of the Lung

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Chapter 387 Congenital Disorders of the Lung

387.1 Pulmonary Agenesis and Aplasia

387.2 Pulmonary Hypoplasia

Jonathan D. Finder

Etiology and Pathology

Pulmonary hypoplasia involves a decrease in both the number of alveoli and the number of airway generations. The hypoplasia may be bilateral in the setting of bilateral lung constraint, as in oligohydramnios or thoracic dystrophy. Pulmonary hypoplasia is usually secondary to other intrauterine disorders that produce an impairment of normal lung development (Chapter 95). Conditions such as deformities of the thoracic spine and rib cage (thoracic dystrophy), pleural effusions with fetal hydrops, cystic adenomatoid malformation, and congenital diaphragmatic hernia physically constrain the developing lung. Any condition that produces oligohydramnios (fetal renal insufficiency or prolonged premature rupture of membranes) can also lead to diminished lung growth. In these conditions, airway and arterial branching are inhibited, thereby limiting the capillary surface area. Large unilateral lesions, such as congenital diaphragmatic hernia and cystic adenomatoid malformation, can displace the mediastinum and thereby produce a contralateral hypoplasia, although usually not as severe as that seen on the ipsilateral side.

387.3 Cystic Adenomatoid Malformation

Diagnosis

Cystic adenomatoid malformations can be diagnosed in utero by ultrasonography (Fig. 387-1). Fetal cystic lung abnormalities can include cystic adenomatoid malformations (40%), pulmonary sequestration (14%) (Chapter 387.4), or both (26%); the median age at diagnosis is usually 21 wk gestation. In 1 series, only 7% had severe signs of fetal distress including hydrops, pleural effusion, polyhydramnios, ascites, or severe facial edema; 96% of the fetuses were born alive, 2 of whom died in the neonatal period. Lesions causing fetal hydrops have a poor prognosis. Large lesions, by compressing adjacent lung, can produce pulmonary hypoplasia in nonaffected lobes (Chapter 387.2). Even lesions that appear large in early gestation can regress considerably or decrease in relative size and be associated with good pulmonary function in childhood. CT allows accurate diagnosis and sizing of the lesion.

Clinical Manifestations

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