Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Congenital Cystic Adenomatoid Malformation, Type II
- Radiologic Findings
- Brief Review
- Congenital cystic adenomatoid malformation is characterized by anomalous fetal development of terminal respiratory structures, resulting in an adenomatoid proliferation of bronchiolar elements and cyst formation. The condition is classified into three types. Type 1, the most common, is characterized by single or multiple large cysts, one to four in number, over 2 cm in diameter. In type 2, multiple small cysts less than 2 cm in diameter are characteristic. Type 3 consists of solid adenomatoid tissue.
This condition occurs with equal frequency in boys and girls; 14% of cases occur in stillborn infants, and 63% have symptoms in the first month of life.
Radiographic study shows marked expansion of what appears to be an entire lung with consequent shift of the mediastinum and compression of the contralateral lung. The involved lung is composed of opaque tissue interspersed with cysts, air-containing spaces of varying size that may contain fluid levels. Occasionally a single cyst predominates. The lesion may initially appear solid if the radiograph is obtained before the fatal lung fluid has drained; it appears cystic only where air replaces the fluid.
In type I, several large cysts fill the hemithorax and displace the heart and mediastinum. In one large cyst dominates the pathology of the process, distinction from congenital lobar emphysema may be difficult. Exceptionally, the cysts may be entirely filled with fluid simulating a type III lesion or another condition entirely. Type II lesions are not often seen radiographically since most infants with this type are stillborn. The radiographic picture is one of multiple small cysts. Type III lesions are rare and show a large solid mass displacing heart and mediastinal structures.
- References
- Keywords
- Lung, Congenital, Congenital Cystic Adenomatoid Malformation, Type II