Chylothorax.

Chylothorax or chylous pleural effusion occurs when chyle accumulates in the pleural space usually secondary to disruption of thoracic lymphatics. Chyle is a milky, white, opalescent fluid that is formed when long-chain triglycerides in the diet are transformed into chylomicrons and very-low-density lipoproteins, which are then secreted into intestinal lacteals. These lymphatic channels coalesce to form the thoracic duct, which transports chyle and ultimately drains it into the left subclavian vein. Any injury to the duct (or its major tributaries) as it courses through the thoracic cavity can lead to a chylous effusion. Diagnosis depends on direct analysis of the fluid by assaying the triglyceride content and, at times, lipid electrophoretic pattern (chylomicrons). Management depends on the underlying cause and the individual clinical circumstances. Nonoperative options include observation, treatment of the underlying disease, dietary modification employing strict medium-chain triglyceride diet or total parenteral nutrition, therapeutic thoracentesis, tube thoracostomy with chemical pleurodesis, and embolization of the thoracic duct. Surgical management may include pleurectomy, talc poudrage, pleuroperitoneal shunting, and repair or ligation of the thoracic duct via thoracoscopy or thoracotomy.