Chylothorax

A chylothorax (or chyle leak) is a type of pleural effusion. It results from lymph formed in the digestive system called chyle accumulating in the pleural cavity due to either disruption or obstruction of the thoracic duct.

In people on a normal diet, this effusion can be identified by its turbid, milky white appearance, since chyle contains high levels of triglycercides. It is important to distinguish chylothorax from pseudochylothorax (pleural effusions high in cholesterol), which has a similar appearance, but is caused by more chronic inflammatory processes, and has a different treatment.

Causes

The condition is rare but serious, and appears in all mammals. It results from leakage of lymph fluid from the thoracic duct (or one of its tributaries). This can result from direct laceration (e.g., from surgery) or from nontraumatic causes. The most common nontraumatic cause is malignancy, especially lymphoma. Less common is left-heart failure, infections, and developmental abnormalities such as Down syndrome and Noonan syndrome.