**2. Congenital cystic adenomatoid malformation of the lung (CCAM)**

#### **2.1. Definition and incidence**

Congenital cystic adenomatoid malformation of the lung (CCAM) is a lesion that is characterized by the presence of a mass of multicystic pulmonary tissue and is accompanied by bronchial proliferation. Its occurrence can be explained by:

• The lack of maturation of the bronchial tissue during the pseudoglandular stage of pulmonary development, which is between the 5th and 6th week of gestation [2]

It is possible to highlight the vascular flow of the lesion that comes from a branch of the pulmonary artery. The use of color Doppler is mandatory to highlight the absence of systemic vasculature and the presence of pulmonary vasculature for CCAM. From the ultrasound

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Both the macrocystic form and the microcystic form can cause fetal hydrops and mediastinal

The macrocystic types are rarely accompanied by fetal hydrops. The size of the lesion determines whether a fetus will develop hydrops or not [9]. Large scale macrocystic lesions cause mediastinal shift and cardiac decompensation, accompanied by increased venous central

What is important to emphasize, is that the degree of the mediastinal shift has no predictive

It should be underlined that there are CCAM hybrid lesions which refer to the presence of both pulmonary and systemic circulation that originates directly from the descending aorta [10].

The ultrasound differential diagnosis will consider the following: congenital diaphragmatic hernia (CDH), bronchopulmonary sequestration (BS), pericardial teratoma, enteric or bronchogenic cysts, bronchial atresia, esophageal duplication, neuroblastoma, brain heterotopia. The differential diagnosis from CDH is not easy. The macrocystic form of CCAM can be confused with CDH left-sided; the intrathoracic stomach may resemble the macrocystic form. Highlighting intestinal peristalsis or emptying the herniated stomach can yield the diagnosis in favor of CDH. In addition, the size of the abdomen is normal, and the abdominal organs

point of view, CCAM will be classified in macrocystic and microcystic (**Figures 2**–**4**).

pressure, followed by the appearance of the fetal hydrops (**Figure 6**).

are in the normal position in case of CCAM (**Figures 7** and **8**).

value for the appearance of the hydrops.

**Figure 2.** CCAM macrocystic: white arrow—lung cyst.

shift (**Figure 5**).


The estimated incidence is of 1 in 25,000 births, up to 1 in 30,000 births [4]. Most ultrasound detected CCAM lesions are unilateral and only 2–3% of them are bilateral and they are more frequently encountered in male fetuses [5]. In the case of unilateral lesions, a single lobe is usually involved and in rare situation it is the whole lung. Vascularization of the multicystic mass comes from a branch of the pulmonary artery. Recently, Stocker has classified CCAM in 5 types, depending on the group of airways involved: Type 0, the lesion is bronchial. Type 1, the lesion is bronchial/bronchiolar. Type 2, the lesion is bronchiolar. Type 3, the lesion is bronchiolar/alveolar. Type 4, the lesion is peripheral [6, 7]. A more practical classification is that which considers the ultrasound antenatal aspect, proposed by Adzick [8] and which describes the lesions as macrocystic or microcystic. Thus, CCAM has the following classification: Macrocystic type I with single or multiple cysts larger than 2 cm in diameter, CCAM type 2 with multiple cysts smaller than 2 cm and larger than 0.5 cm in diameter and type 3 with multiple cysts, less than 5 mm in size and with a hyperechogenic aspect. By advancing Adzick's classification, a simpler ultrasound classification was established by Wilson [9]. Thus, the ultrasound appearance is a cystic variant and a solid (or microcystic) variant. The cystic variant is multilocular lesions with cysts of various sizes from a few millimeters to 10 cm. The solid microcystic variant comprises a hyperechogenic mass.
