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CHAPTER 55

Chylothorax

Jean-Martin Laberge
Kokila Lakhoo
Behrouz Banieghbal

Introduction the thoracic duct. Lymphangiomatosis or diffuse lymphangiectasia may
Chylothorax is a rare entity and is defined as an effusion of lymph in produce chylous effusion in the pleural space and peritoneal cavity.
the pleural cavity. The chyle may have its origin in the thorax or in the Extensive bouts of coughing have been reported to cause rupture of the
abdomen or in both. Leakage usually occurs from the thoracic duct or thoracic duct, which is particularly vulnerable when full following a
one of its main tributaries. fatty meal. Other causes include mediastinal inflammation, subclavian
Demographics vein or superior vena caval thrombosis, and misplaced central venous
catheters (Table 55.1).
There are no known racial, gender, age, or geographical variations to
chylothorax. This is due to its aetiology. However, it is known to occur Table 55.1: Causes of chylothorax.
in up to 4% of patients after cardiothoracic surgery.
Lymphatic malformation (nontrauma)
Pathophysiology Thoracic duct atresia/aplasia/hypoplasia/dysplasia
The thoracic duct develops from outgrowths of the jugular lymphatic Lymphangioma
sacs and the cisterna chyli. During embryonic life, bilateral thoracic Lymphangiomatosis
lymphatic channels are present, each attached in the neck to the cor- Intestinal lymphangiectasia (protein-losing enteropathy)
responding jugular sac. As development progresses, the upper third Fontan procedure
of the right duct and the lower two-thirds of the left duct involute and Thoracic duct injury (trauma)
close. The wide variation in the final anatomic structure of the main Cardiothoracic operations
ductal system attests to the multiple communications of the small ves- Oesophageal atresia
sels comprising the lymphatic system. The thoracic duct originates Diaphragmatic hernia
in the abdomen at the cisterna chyli located over the second lumbar Penetrating trauma (stab or gunshot injury)
vertebra. The duct extends into the thorax through the aortic hiatus and Malignant
then passes upward into the posterior mediastinum on the right before Lymphoma
shifting toward the left at the level of the fifth thoracic vertebra. It then Kaposi sarcoma
ascends posterior to the aortic arch and into the posterior neck to the Mediastinal teratoma
junction of the subclavian and internal jugular veins. Infectious
The chyle contained in the thoracic duct conveys ap proximately Tuberculosis
three-fourths of the ingested fat from the intestine to the systemic Filariasis
circulation. The fat content of chyle varies from 0.4 to 4.0 g/dl. The Pneumonia
large fat molecules absorbed from the intestinal lacteals flow through the Pleuritis and empyema
cisterna chyli and superiorly through the thoracic duct. The total protein
content of thoracic duct lymph is also high. The thoracic duct also carries Idiopathic (associated with)
white blood cells, primarily lymphocytes (T cells)—approximately Down syndrome
2,000 to 20,000 cells per milliliter. When chyle leaks through a thoracic Noonan syndrome
duct fistula, considerable fat and lymphocytes may be lost. Eosinophils Gorham’s disease
are also present in a higher proportion than in circulating blood. The Hydrops foetalis
chyle appears to have a bacteriostatic property, which ac counts for the Turner syndrome
rare occurrence of infection complicating chylothorax. Lymphoedema
Transudative
Aetiology Cirrhosis of the liver
Effusion of chylous fluid into the thorax may occur spontaneously in Fontan procedure
newborns and has usually been attributed to congenital abnormalities Heart failure
of the thoracic ducts or trauma from delivery. The occurrence of chylo- Nephritic syndrome
thorax in most cases cannot be related to the type of labor or delivery, Miscellaneous
and lymphatic effusions may be discovered prenatally. Sarcoidosis
Chylothorax in older children is rarely spontaneous and occurs Amyloidosis
almost invariably after trauma or cardiothoracic surgery; however,
some patients with thoracic lymphangioma may present in this older
age group. Operative injury may be in part a result of anatomic
variations of the thoracic duct. Neoplasms, particularly lymphomas and
neuroblastomas, have occasionally been noted to cause obstruction of