Chylothorax. A review of the literature and report of 3 cases.

Lymph vessels develop during the 9th week of fetal life. During the 14th week they form wide lymph trunks in the connective tissue through the tissue planes of least resistance, which divide the parenchyma of the lung into distinct lobules. By the 20th week this lobulation is less distinctive, the connective tissu decreases, and the lymph vessels become thinner in relation to the parenchyma of the lung.,6 Van Pernis7 studied the thoracic duct in 1081 cadavers. The duct arises from the cisterna chyli, which overlies the anterior surface of the 2nd lumba~vertebra and lies posterior to and to the right of the aorta. The duct then ascends through the aortic hiatus on 'the anterior surface of the vertebral bodies between the aorta and azygos vein. Between the 7th and 5th thoracic vertebrae it crosses to the left and ascends behind the arch ofthe aorta and subclavian artery into the base of the neck, where it empties at or near th~ junction of the left subclavian and internal jugular veins. The duct is always a single structure between T8 and T5. The thoracic duct receives all the lymph of the body except that from the right hemithorax, right upper limb and right side of the head and neck. Lymph from the parietal ple~ra reaches the thoracic duct via posterior intercostal lymphaocs. The lymph from the visceral pleura and lungs drains into the bronchomediastinal trunk on each side. This in turn may join the thoracic duct or the innominate vein. The lymphographic anatomy of chylothorax is described by Schulman er al. 8 Simple obstruction or ligation of the thoracic duct hardly ever causes chylothorax because a rich collateral system allows chyle