Non-traumatic chylothorax: diagnostic and therapeutic strategies

Abstract

Non-traumatic chylothorax refers to accumulation of chyle in the pleural space in the absence of any traumatic disruption to the thoracic duct. Chyle originates from the intestines and is transported via the thoracic duct into systemic circulation. The anatomical course of the thoracic duct is complex with considerable variation; therefore, development of chylothorax is dependent on the site and level of the thoracic duct defect. Non-traumatic chylothorax is associated with a wide range of medical disorders, but malignancy accounts for three-quarters of cases. In up to 9% of cases, the aetiology remains unknown (termed idiopathic chylothorax). Gross appearance of pleural fluid is neither sensitive nor specific enough to diagnose chylothorax; therefore, biochemical analysis of the pleural fluid is required. Pleural fluid triglyceride level >1.24 mmol·L−1 (110 mg·dL−1) with a cholesterol level <5.18 mmol·L−1 (200 mg·dL−1) is diagnostic of chylothorax. In borderline cases, lipoprotein electrophoresis can help confirm the diagnosis by detecting chylomicrons in the pleural fluid.Once the diagnosis of chylothorax is confirmed, the next step is to find the cause and identify the leakage point, for which various lymphatic specific radiological investigations may have an important role. There is paucity of data on the most suitable approach to manage non-traumatic chylothoraces and treatment often depends on the underlying cause. In general, conservative treatment is tried first, usually for a limited time, before considering more invasive measures. A multidisciplinary approach is recommended with close liaison among the respiratory physicians, thoracic surgeons, oncologists, interventional radiologists, dietitians and pharmacists.Educational aimsTo review the pathophysiology, aetiology, and epidemiology of non-traumatic chylothorax.To discuss diagnostic and therapeutic strategies in the management of non-traumatic chylothorax.

Pleural fluid milkshakes: three cases with different aetiologies

“…Although currently there is no clear consensus on the most suitable approach to manage chylothorax, efforts should be aimed at identifying and correcting the underlying cause 1 . In our first 2 cases, commencement of disease‐specific therapy led to resolution of chylothorax with no recurrence.…”

“…CT chest can identify mediastinal lesions and lymphadenopathy secondary to lymphoproliferative disorders, tuberculosis and malignancy. Benign conditions such as misplaced central catheters and pacemaker wires leading to chylothorax can be identified on CT chest as well 1,6 . Lymphangioscintigraphy, computed tomography lymphangiography and magnetic resonance lymphangiography are being increasingly used instead of invasive lymphangiography to locate the exact site of chyle leak, which can inform subsequent duct repair surgeries 10 …”

“…Non‐invasive measures such as low‐fat diet with medium chain triglyceride supplementation to replace nutrients lost in chyle and to reduce chyle formation is successful in up to 50% of cases 1 . Octreotide may be considered either in conjunction with dietary regimens or when chyle loss persists despite other measures 1 . In cases with large, rapidly recurring, or refractory chylous effusions, more invasive interventions to provide symptomatic relief and to minimize nutritional loss may be required.…”

“…Malignancy is the leading cause of non-traumatic chylothorax while thoracic surgery is the major cause of traumatic chylothorax. 1,5 Lymphoma, being the most common malignant cause, is responsible for up to 75% of cases of malignant chylothorax. 6 Lymphomatous infiltration of the thoracic duct or duct compression by enlarged lymph nodes is responsible for chylothorax among lymphoma patients.…”

“…Chyle (from the Greek word ‘chylos’ which means ‘juice’) is a milky fluid composed of lymph and fatty acids absorbed from the intestinal system. Chylothorax refers to pathological accumulation of chyle in the pleural space 1 . Diagnosis of chylothorax was (and still commonly is till today) initially based on milky appearance of pleural fluid 2 .…”