FIGURE 10-24 Transverse (A) and sagittal (8) images of a 26-week fetus with a very large left-sided microcystic congenital cystic adenomatoid malformation (CCAM). The mass () fills the thorax and has shifted the heart to the far right side of the chest, with development of ascites (asterisks). Fortunately, the mass did not continue to grow, the ascites resolved, and the neonate was delivered at term and did well following resection.
termed macrocystic, and lesions with cysts <5 mm are termed microcystic (Adzick, 1985).
In a review of 645 CCM cases, the overall survival rate exceeded 95 percent, and 30 percent of cases demonstrated apparent prenatal resolution. The other 5 percent of cases typically very large lesions with associated mediastinal shift were complicated by hydrops, and the prognosis was poor (Cavoretto, 2008). CCAMs often become less conspicuous with advancing gestation. However, a subset of CCAMs dem onstrates rapid growth between 18 and 26 weeks' gestation.
lesions to forestall growth and potentially ameliorate hydrops (Curran, 2010; Peranteau, 2016). If a large dominant cyst is present, thoracoamnionic shunt placement may lead to hydrops resolution. Fetal therapy for CCAM is discussed in Chapter 16 (p.i324).
Also called a bronchopulmonary sequestration, this abnormal ity is an accessory lung bud "sequestered" from the tracheo bronchial tree, that is, a mass of nonfunctioning lung tissue.
Most cases diagnosed prenatally are extralobar, which means they are enveloped in their own pleura. Overall, however, most sequestrations present in adulthood and are intralobar-within the pleura of another lobe. Extralobar pulmonary sequestra tion is considered significantly less common than CCAM, and no precise prevalence has been reported. Lesions have a left sided predominance and most often involve the left lower lobe.
Of cases, 10 to 20 percent are located below the diaphragm, 10 percent of cases (Yildirim, 2008).
Sonographically, pulmonary sequestration presents as a homogeneous, echogenic thoracic mass (Fig. 10-25A). Thus, it may resemble a microcystic CCAM. However, the blood supply is from the systemic circulation-from the aorta rather than the pulmonary artery (see Fig. 10-25B). In 5 to 10 percent with pulmonary sequestration, a large ipsilateral pleural efusion develops, and without treatment, this may result in pulmonary hypoplasia or hydrops (see Fig. 1 0-25C,D). Therapeutic thoracoamnionic shunting of efusions is discussed in Chapter 16 (p. 324). Hydrops may also result from mediastinal shift or high-output cardiac failure due to the left-toright shunt imposed by the mass. In the absence of a pleural efusion, the reported survival rate exceeds 95 percent, and 40 percent of cases demonstrate apparent prenatal resolution (Cavoretto, 2008).