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KEY POINTS
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Key Points

  • CCAM is cystic malformation of pulmonary tissue and, unlike BPS, typically has a pulmonary blood supply.

  • CCAM has been subdivided into five types, depending on the number and size of cystic changes; additionally hybrid lesions in which features of BPS coexist have been described.

  • Prenatal ultrasound can detect either cystic or solid mass in the chest without a systemic vascular supply.

  • Differential diagnosis includes BPS, diaphragmatic hernia, and bronchogenic cyst.

  • Cases of CCAM with a dominant large cyst, or with a CCAM volume ratio greater than 1.6, appear to be at most risk of developing hydrops in utero, which is associated with very poor prognosis; in contrast, some cases of CCAM also regress spontaneously in utero.

  • Fetal intervention is possible by means of thoracoamniotic shunting for cases of hydrops with a dominant cyst, or by means of open fetal surgical resection for cases of hydrops with a microcystic appearance; additionally a course of antenatal corticosteroids may also be beneficial.

  • Delivery should occur electively, at term, in a tertiary care center with adequate pediatric surgical facilities available.

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CONDITION
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Congenital cystic adenomatoid malformation (CCAM) of the lung is a lesion characterized by a multicystic mass of pulmonary tissue with a proliferation of bronchial structures (Stocker et al., 1977; Miller et al., 1980). It may represent a failure of maturation of bronchiolar structures, occurring at approximately the 5th or 6th week of gestation during the pseudoglandular stage of lung development (Stocker et al., 1977; Miller et al., 1980; Shanji et al., 1988). Alternatively, it may represent focal pulmonary dysplasia, since skeletal muscle has been identified within the cyst walls (Leninger and Haight, 1973). Others have suggested that it may be the result of airway obstruction (Demos and Teresi, 1975; Cochia and Sobonya, 1981; Moerman et al., 1992; Langston, 2003). The gestational age and location of the airway obstruction may determine whether CCAM, bronchopulmonary sequestration, or lobar emphysema results (Keswani et al., 2005; Kunisaki et al., 2006).

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CCAM is slightly more common in males and may affect any lobe of the lung (Hernanz-Schulman, 1993). The lesion is unilobar in 80% to 95% of cases and bilateral in fewer than 2% (Stocker et al., 1977). Unlike bronchopulmonary sequestration (BPS), CCAMs have a communication with the tracheobronchial tree, albeit via a minute tortuous passage. In contrast to BPS, CCAMs derive their arterial blood supply and venous drainage from normal pulmonary circulation, but anomalous arterial and venous drainage of CCAM have also been reported (Rashad et al., 1988) as well as the so-called “hybrid” CCAMs that have a systemic blood supply (Cass et al., 1997).

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Stocker et al., (1977) originally subdivided CCAM into three types based on their pathologic characteristics (Figure 35-1). More recently, Stocker revised this classification to ...

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