Chylothorax

Chylothorax
Three bottles of chyle drained from a chylothorax
Specialty	Respiratory medicine
Symptoms	None, breathlessness
Complications	Dehydration, malnutrition, abnormal electrolyte levels, weakened immune system
Types	Low output, high output
Causes	Complication of surgery, trauma, cancer, infections, lymph vessel abnormalities
Diagnostic method	X-ray, CT scan, thoracic MRI, fluid sampling
Treatment	Removing fat from the diet, decreasing lymph flow, chest tube, surgery
Medication	Octreotide, midodrine, and sirolimus
Prognosis	~10% risk of death

A chylothorax is an abnormal accumulation of chyle, a type of lipid-rich lymph, in the pleural space surrounding the lung. The lymphatic vessels of the digestive system normally return 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.^[1] About 2–3% of all fluid collections surrounding the lungs (pleural effusions) are chylothoraces.^[2] 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.^[3]