chylothorax

Chylothorax occurs when the thoracic duct is disrupted (traumatic causes: thoracic surgery, especially esophagectomy or cardiac surgery, blunt/penetrating trauma) or obstructed (non-traumatic causes: lymphoma is the most common malignant cause, other cancers, lymphangioleiomyomatosis, tuberculosis, or congenital lymphatic abnormalities in neonates). The thoracic duct carries chyle—lymphatic fluid rich in triglycerides absorbed from the intestine via lacteals—from the cisterna chyli up through the thorax to drain into the junction of the left subclavian and internal jugular veins. Disruption causes leakage of this lipid-rich fluid into the pleural space. Diagnosis is confirmed by pleural fluid analysis showing a milky, turbid appearance and triglyceride level >110 mg/dL (with levels <50 mg/dL essentially ruling it out); lipoprotein electrophoresis showing chylomicrons is definitive if triglyceride level is equivocal (50-110 mg/dL). Clinically, patients present with dyspnea, cough, and dullness to percussion; chylothorax is exudative but does not typically cause the inflammatory response of empyema (fluid is usually not foul-smelling). Complications from chronic chylothorax include malnutrition, immunosuppression (loss of lymphocytes and immunoglobulins), and electrolyte disturbances due to loss of proteins and fat-soluble vitamins. Management includes dietary modification (medium-chain triglyceride diet or total parenteral nutrition to reduce chyle flow), pleurodesis, octreotide, or surgical thoracic duct ligation for persistent cases. It's important to differentiate chylothorax from pseudochylothorax (cholesterol effusion), which occurs in chronic conditions like rheumatoid arthritis or tuberculosis and has high cholesterol but low triglycerides.