Wiktionary
chylothorax
n. An accumulation of chyle in the pleural cavity.
Wikipedia
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.