A chylothorax is an abnormal accumulation of chyle, a type of lipid-rich lymph, in the space surrounding the lung. The lymphatics of the digestive system normally returns lipids absorbed from the small bowel via the thoracic duct, which ascends behind the esophagus to drain into the left brachiocephalic vein. If normal thoracic duct drainage is disrupted, either due to obstruction or rupture, chyle can leak and accumulate within the negative-pressured pleural space. In people on a normal diet, this fluid collection can sometimes be identified by its turbid, milky white appearance, since chyle contains emulsified triglycerides. Chylothorax is a rare but serious condition, as it signals leakage of the thoracic duct or one of its tributaries. There are many treatments, both surgical and conservative. About 2–3% of all fluid collections surrounding the lungs (pleural effusions) are chylothoraces. It is important to distinguish a chylothorax from a pseudochylothorax (a pleural effusion that happens to be high in cholesterol), which has a similar appearance visually but is caused by more chronic inflammatory processes and requires a different treatment. Signs and symptoms
The symptoms of a chylothorax depend its size and the underlying cause. A small chylothorax may not cause any symptoms and only be detected on a chest X-ray performed for another reason.
Infectious causes are also observed, most often in developing countries. The most common cause of an infectious chylothorax is a complication of tuberculous lymphadenitis. Other possible causative infections include aortitis, histoplasmosis, and filariasis. Chylothorax can also be congenital, and may co-occur with other lymphatic malformations like lymphangiectasis and lymphangiomatosis. Other conditions like tuberous sclerosis, congenital heart disease, trisomy 21 (Down syndrome), Noonan syndrome, or Turner syndrome (missing X chromosome) are also possible causes of congenital chylothorax. Other, more rare causes of congenital chylothorax include Castlemans disease, yellow nail syndrome, Waldenströms macroglobulinemia, sarcoidosis, venous thrombosis, thoracic radiation, macroglobulinemia, amyloidosis, and a goiter. These diseases cause chylothorax by obstructing or destroying the thoracic duct. Also, parenteral nutrition has been a possible cause; a quick dose of total parenteral nutrition can overwhelm the thoracic duct, causing the chyle to leak into the surrounding pleural space. Traumatic
Iatrogenic chylothorax after surgery is the most common variety of chylothorax. It is a common and serious complication of a pneumonectomy. It is especially common in surgeries requiring mediastinal dissection. The probability of chylothorax depends on the type of surgery. The surgery with the highest risk of chylothorax is an esophagostomy, with a 5-10% risk of chylothorax. Lung resection and mediastinal node dissection have the second highest risk, with 3-7% risk. Other operations like mediastinal tumor resection, thoracic aneurysm repair, sympathectomy, and any other surgeries that take place in the lower neck or the mediastinum can lead to chylothorax.