Developmental lymphatic disorders of the thorax.

Developmental disorders that involve the lymphatic channels of the thorax, although rare, are important and must be distinguished from the more common causes of chest masses or diffuse lung disease. There are four major types of developmental lymphatic disorders that affect the thorax: lymphangiectasis, characterized by congenital anomalous dilatation of pulmonary lymph vessels; localized lymphangioma, a rare and benign, usually cystic, lesion characterized by masslike proliferation of lymph vessels; diffuse lymphangioma, a proliferation of vascular, mainly lymphatic, spaces in which visceral and skeletal involvement are common; and lymphangioleiomyoma, which involves a haphazard proliferation of smooth muscle in the lungs and dilatation of lymphatic spaces. These characteristic findings can be seen with radiographic studies as well as with histologic evaluation. The discovery of one of these lymphatic disorders may prompt an investigation for associated congenital anomalies, including Noonan syndrome, asplenia, Gorham syndrome, and tuberous sclerosis.