**5.2. Ultrasound diagnosis**

The diagnosis of bronchogenic cysts can be established on the axial section of the four chambers of the heart. It appears as a unilateral, circumscribed, thin wall lesion (**Figure 13**).

They may rarely be multilocular. The bronchogenic mediastinal cyst can compress the trachea or bronchi so that the distal lung becomes dense and expansive, in this way lending the specific echographic aspect for the cystic adenomatoid malformation [26]. The differential diagnosis includes: CCAM, esophageal duplication cyst, pericardial cyst, duplication cyst and lymphangioma. In CCAM, the tissue surrounding the cyst is hyperechogenic.

**Figure 13.** Bronchogenic cyst: star—lung mass.
