The Netherlands Journal of Medicine
ReviewChylothorax
Introduction
Chylothorax is defined as an accumulation of chyle in the pleural space caused by disruption of the thoracic duct or one of its major divisions. Although rare, physicians should be aware of the possibility that pleural effusion can be caused by chyle.
Loss of chyle results in the loss of large amounts of fluid, electrolytes, protein, fat, fat-soluble vitamines and lymfocytes, predominantly the T-cell variety. In addition respiration and circulation will be impaired by fluid accumulation. Eventually chylothorax can lead to a life threatening state of malnutrition.
This report deals with anatomy, physiology, diagnosis, etiology, and management of chylothorax.
Three patients with different causes of chylothorax were recently seen in our hospital. They were treated in three different ways. The patient characteristics are summarized in Table 1.
Section snippets
Anatomy
The thoracic duct is formed by the lymph vessels from the peritoneal cavity and the lower parts of the body. At its origin it usually extends from a dilatation, the cisterna chyli, which lies just anterior to the first or second lumbar vertebra. Through the aortic hiatus the duct passes the diaphragm, continues upwards into the posterior mediastinum on the right side of the vertrebral column between the aorta and the azygos vein. It crosses the midline to the left between the sixth and fourth
Physiology
Chyle contains lymph, mainly from intestinal origin. It has a high content of triglycerides. The odourless fluid is turbid and milky due to the presence of spherical triglyceride containig particles, the chylomicrons.
However, not every milky pleural effusion is chyle. Exsudates that have been present in the pleural space for a long time, have the tendency to become enriched with cholesterol, especially when the pleura is fibrotic. A high content of cholesterol may also yield a thick, opalescent
Differentiation on gross appearance
In a retrospective study, the milky (‘chylous’) appearance was only found in 18 of 38 patients (47%). Chyle appeared as a bloody effusion in 26%, and was yellow turbid in 10%. Chylous effusions are hardly ever serous or serosanguinous. After starvation, the milky appearance may disappear. A chylous effusion becomes milky again 3 h after oral intake of a few spoons of cream.
Chyle can easily be differentiated from pseudochyle and empyema. After centrifugation, empyema leaves a clear supernatant
Etiology and management
Chylothorax usually is the result of leakage of the thoracic duct. This is due to rupture, extrinsic compression or obliteration of the duct. In case of compression or obliteration chylous effusion will develop after the congestion of the numerous collaterals and lymphatic-venous anastomoses by lymph.
Before it enters the pleural space, first a collection of chyle below the pleura, a chyloma, is formed. Later the pleura bursts and the chyle flows into the pleural space. A chyloma is rarely seen
Summary
Chylothorax is a rare but serious disorder that can have severe repiratory and metabolic consequences. The anatomy of the lymphatic system has many variations and, as demonstrated in our three cases, the etiology of chylous effusion is diverse. Drainage and dietary modification can be a successful treatment of chylothorax, but prolonged conservative therapy can result in malnutrition, metabolic disturbances and immunodeficiency. Appropriate timing of surgical intervention is essential. Since
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