Chylothorax: pathophysiology, diagnosis, and management-a comprehensive review

Abstract

Chylothorax is a rare condition characterized by the accumulation of chyle in the pleural space. While it accounts for a small percentage of pleural effusions, chylothorax can lead to significant morbidity and mortality. This article provides a comprehensive overview of chylothorax, covering its relevant anatomy, aetiology, pathophysiology, clinical features, diagnosis, and management. Injury or disruption to the thoracic duct (which is responsible for chyle transport) leads to the development of chylothorax. This may result from trauma, such as iatrogenic injury during surgery, or non-traumatic causes, including malignancy, lymphatic disorders, and heart failure. Recognition of the underlying cause is essential to tailor management. Clinical presentation varies, with symptoms linked to rate of chyle accumulation and the causative condition. Diagnosis relies on pleural fluid analysis, with demonstration of elevated triglyceride levels (>110 mg/dL) and reduced cholesterol levels (<200 mg/dL) being the key diagnostic criteria employed in clinical practice. Various imaging modalities, including computed tomography (CT) scans and lymphatic-specific investigations, may be utilised to aid identification of the site of chyle leak, as well as determine the likely underlying cause. Chylothorax management is multifaceted, with conservative approaches such as dietary modification and pharmacological interventions often initiated as first-line treatment. Drainage of chylous effusion may be necessary for symptom relief. When conservative methods fail, interventional procedures like thoracic duct ligation or embolization can be considered. Due to the diverse aetiological factors and patient characteristics associated with chylothorax, individualized management strategies are recommended. Nonetheless, management of chylothorax is an evolving field with a paucity of high-quality evidence or standardized guidelines, highlighting the importance of ongoing research and a multidisciplinary approach to optimize individual patient care.

Keywords: Chylothorax; effusion; pleural disease.

Figure 1

Diagrammatic representation of the course of the thoracic duct (pale green) in relation to its surrounding structures. The thoracic duct arises at the cisterna crista in the abdomen and enters the thorax through the diaphragm (shown as a black curvilinear band) at the aortic hiatus. The thoracic duct ascends superiorly and crosses to the left of the midline at the level of the thoracic plane (between T4 and T6 vertebrae) before terminating at the junction of the left internal jugular and subclavian veins.

Figure 2

Proposed mechanisms (boxes 1 to 4) underpinning the development of non-traumatic chylothorax. The pleural cavity is depicted in blue, while the peritoneal cavity is depicted in orange, separated by the diaphragm (represented as a black curvilinear band). The thoracic duct and associated lymphatic structures are shown in green. Increased hydrostatic pressure, lymphatic dysfunction, and direct invasion by malignant cells may occur at any level of the thoracic duct. Examples relating to each of these pathophysiological mechanisms are summarised in Table 1.

Figure 3

Proposed approach to the management of chylothorax, highlighting the various invasive and non-invasive treatment options available. Initial management is usually focused on conservative therapies, particularly in the case of non-traumatic chylothorax, where early surgical/invasive procedures are less critical compared to traumatic chylothorax. In cases of persistent chyle leak, a multi-disciplinary approach is advocated to ensure individualized patient care is optimized. This may involve radiologically-guided interventions (e.g., thoracic duct embolization) or surgical intervention (e.g., thoracic duct ligation) depending on patient suitability and local resources. ICD, intercostal drain; MCTs, medium-chain triglycerides; IPC, indwelling pleural catheter.