Morphologic analysis of foregut cysts in the thorax

Eighty six cases of thoracic foregut cysts were histologically selected and classified as either respiratory (bronchogenic or bronchial) or enteric. Most are homogeneous water density masses which are located in the mediastinum and frequently based around the carina. There is a tendency for the carina based group to extend either posteriorly or inferiorly into the retrocardiac area. These masses tend to be right sided and partially obscured by surrounding normal structures. The simple enteric cysts are not always distinguishable from the respiratory cysts, but tend to be larger and more posterior. In contrast with the simple enteric cysts, the neurenteric cysts should be very characteristic because of their associated vertebral body anomalies. The intrapulmonary cysts may present as either a mass or cavity and such an appearance may be nonspecific. However, when the diagnosis is considered either preoperatively or on histologic grounds, signs of an underlying inflammatory process, such as surrounding infiltrate, bronchiectasis, pleural scarring or pleural effusion are good evidence for seriously questioning the diagnosis of a congenital cyst.