Congenital malformations of the cervicothoracic lymphatic system: embryology and pathogenesis.

Abstract

Familiarity with the embryology of the lymphatic system is helpful in understanding the pathogenesis and radiologic appearance of lymphangiomas of the cervicothoracic region. By considering anatomic location and radiologic appearance, one can predict the type of lymphangioma present, the primordial lymph sac from which the malformation arose, and when it formed in embryonic life. Cystic hygromas are composed of large, dilated lymphatic spaces. They form when a primordial lymph sac fails to reestablish communication with the central venous system from which it arose. These lesions may also resuit from an aberrant bud arising from a primordial lymph sac. Cayernous and capillary lymphangiomas are composed of smaller lymphatic channels. They form from abnormally sequestered buds of the developing lymphatic mesenchyme responsible for the fine meshwork of terminal branches in the periphery of the embryo. Their growth may be inhibited by the relatively tougher tissues in the periphery (eg, skin and muscle) compared with the relatively loose fatty connective tissue in which cystic hygromas form. Not only can all types of lymphangioma occur in one lesion, but lymphatic and vascular malformations may also coexist.

Expression of the fms-like tyrosine kinase 4 gene becomes restricted to lymphatic endothelium during development.

“…However, lymphatic vessels were difficult to identify, because no specific markers are available for them. Since the beginning of the 20th century, three different theories concerning the origin of the lymphatic system have been presented (11,35,36). The most widely accepted theory was proposed by Florence Sabin (10), who suggested that during the fetal period lymphatic structures sprout from large central veins in certain locations to form the primordial lymph sacs.…”

“…The most widely accepted theory was proposed by Florence Sabin (10), who suggested that during the fetal period lymphatic structures sprout from large central veins in certain locations to form the primordial lymph sacs. Subsequently, the sacs enlarge, coalesce, and form new sprouts, which grow into the periphery of the embryo (11,12,35,36).…”

Thoracic lymphangioma in adults: CT and MR imaging features.

“…The origin of lymphangiomas is controversial; they may be developmental [9,10], hamartomatous [ii], or neoplastic [12]. At least 90% of lymphangiomas manifest as a mass in the neck or axilla in patients less than 2 years old [9], with a reported male predominance [1 3].…”

The ultrasonographic diagnosis of cystic cervical lesions: a pictorial essay

“…Uncommonly, they are also described in other sites, such as the mediastinum (5%), axilla (20%), abdominal cavity (in the colon, liver and spleen), retroperitoneum (in the kidneys), scrotum and, very rarely, in the skeletal system [25,26].…”