Chylothorax

Chylothorax is accumulation of chyle (lymphatic fluid rich in triglycerides) in the pleural space from thoracic duct disruption or obstruction.

• Causes: trauma (surgical injury during oesophagectomy, cardiac surgery, lung resection, neck dissection, 0.5 to 4%; blunt/penetrating trauma), malignancy (lymphoma 50% of non traumatic, metastatic cancer), congenital (neonatal, most common cause of effusion in newborns), lymphangioleiomyomatosis, sarcoidosis, tuberculosis, filariasis, venous thrombosis (SVC, subclavian), yellow nail syndrome, Noonan syndrome, amyloidosis, idiopathic.
• Thoracic duct anatomy: from cisterna chyli to left subclavian-jugular junction; injury above T5 causes left effusion, below T5 right effusion.
• Complications: malnutrition, lymphopenia, immunosuppression (loss of T lymphocytes, immunoglobulins), dehydration, respiratory compromise.
• Chylous leak can reach 1 to 4 L per day; mortality up to 50% historically if untreated.

• Progressive dyspnoea and cough, chest discomfort (often painless), fatigue, weight loss; fever uncommon.
• Reduced breath sounds, dullness; post operative effusion with milky output after feeding.
• Signs of cause: lymphadenopathy, facial swelling, nail changes (yellow nail syndrome).

• Pleural fluid appearance: milky, opalescent, though may be serous in fasting patients.
• Biochemistry: triglycerides over 110 mg/dL (1.24 mmol/L) is diagnostic (below 50 mg/dL excludes); chylomicrons on lipoprotein electrophoresis; cholesterol low (below 200 mg/dL), lymphocyte predominant cell count. Pseudochylothorax (chronic effusion with cholesterol crystals, cholesterol over 200 mg/dL, triglycerides low) from rheumatoid pleurisy, tuberculosis.
• Chest radiograph and CT chest/abdomen for mediastinal mass, lymphadenopathy, thoracic duct injury or obstruction.
• Lymphangiography, lymphoscintigraphy, magnetic resonance lymphangiography to locate the leak; cytology, flow cytometry, pleural biopsy.
• Assess nutritional state, lymphocytes, immunoglobulins.

Conservative (first line for output under 1 L/day, non malignant)

• Chest drainage if symptomatic; stop oral fat: nil by mouth with total parenteral nutrition, or a fat free diet with medium chain triglycerides (absorbed by portal system), for 1 to 2 weeks.
• Octreotide 50 to 100 micrograms SC three times daily (or 0.5 to 10 micrograms/kg/h infusion), somatostatin analogues reduce lymph flow; midodrine 5 to 10 mg three times daily; etilefrine.
• Nutritional support, correct electrolytes, fluid replacement, albumin; monitor immune function.

Interventional

• Thoracic duct embolisation (percutaneous via cisterna chyli puncture with coils/glue) success 70 to 90%; thoracic duct disruption.
• Surgical ligation of the thoracic duct (VATS, with mass ligation at diaphragm; pre-operative cream or olive oil 100 mL intake to identify leak) if leak over 1 L/day for 5 days, over 500 mL/day for 7 days, or persistent beyond 2 weeks, or nutritional compromise.
• Pleurodesis (talc 4 to 5 g) or pleurectomy; pleuroperitoneal shunt for refractory cases.

Cause specific

• Malignant chylothorax: chemotherapy (lymphoma regimens), radiotherapy, indwelling pleural catheter.
• Lymphangioleiomyomatosis: sirolimus 2 mg daily (trough 5 to 15 ng/mL).
• Congenital: octreotide, fibrin glue, surgery.
• Treat infection, venous thrombosis (anticoagulation, stent).
• Follow up with nutrition and chest imaging.