First described by Wernher in 1843, cystic hygroma (CH) is a cystic lymphatic lesion that can affect any anatomic subsite in the human body. Currently, this lesion is more commonly referred to as a lymphatic malformation (LM). LMs usually affects the head and neck (~75%), with a predilection for the left side. Within the neck, the posterior triangle tends to be most frequently affected. Approximately 20% of LMs occur in the axilla; less common subsites include the mediastinum, groin, and retroperitoneum.
LM is synonymous with cystic lymphangioma, which is also known as a macrocystic lymphatic malformation and was first described in 1828 by Redenbacker.
LMs are thought to arise from a combination of the following:
Failure of lymphatics to connect to the venous system
Abnormal budding of lymphatic tissue
Sequestered lymphatic rests that retain their embryonic growth potential
These lymphatic rests can penetrate adjacent structures or dissect along fascial planes and eventually become canalized. These spaces retain their secretions and develop cystic components because of the lack of a venous outflow tract. The nature of the surrounding tissue determines whether the lymphangioma is capillary, cavernous, or cystic.
LMs tend to form in loose areolar tissue, whereas capillary and cavernous forms of lymphangiomas tend to form in muscle. Studies using cell proliferation markers have demonstrated that lymphangioma enlargement is related more to engorgement than to actual cell proliferation. Molecular studies suggest that vascular endothelial growth factor C (VEGF-C) and its receptors may play an important role in the development of LMs. 
In addition to congenital development, LMs can be acquired. They can arise from trauma (including surgery), inflammation, or obstruction of a lymphatic drainage pathway.
Karyotypic abnormalities are present in 25-70% of children with LM. LM has been noted to be more common in persons with Turner syndrome, Down syndrome, Klinefelter syndrome, and trisomy 18 and 13, though these are not considered to be causative.
In addition, several nonchromosomal disorders, including Noonan syndrome, Fryns syndrome, multiple pterygium syndrome, and achondroplasia, are associated with an increased incidence of LM. Intrauterine alcohol exposure has been associated with the development of LM. Dissolution of bone caused by either LM or hemangiomas is termed Gorham-Stout syndrome.
The incidence of LM is estimated to be one case per 6000-16,000 live births.
Most LMs (50-65%) are evident at birth, and 80-90% of them present by age 2 years. Some authors believe that all LMs are present at birth, even though they may not have fully manifested at that time. LM can be visualized by means of abdominal ultrasonography by 10 weeks' gestation, though transvaginal ultrasonography provides superior detail. Fast-spin magnetic resonance imaging (MRI) can also be used to determine the extent of fetal LM. Elevated alpha fetoprotein levels in amniocentesis fluid has been reported in pregnancies with LM.
The sex distribution is equal. Most series report no racial predominance, though a decreased incidence in African Americans has been described.
In some series, the reported mortality has been as high as 2-6%, usually secondary to pneumonia, bronchiectasis, and airway compromise. Obviously, this figure is pertinent in the larger-sized lesions.
As would be expected, morbidity depends on the anatomic location of the LM. In general, morbidity is related to cosmetic disfigurement and impingement on other critical structures, such as nerves, vessels, lymphatics, and the airway.
Unlike hemangiomas, LMs do not commonly resolve spontaneously. Recurrence is rare when all gross disease is removed. If residual tissue is left behind, the expected recurrence rate is approximately 15%.
In prenatal CH, diagnosis after 30 weeks' gestation is considered a positive prognosticator. A study by Lejeunesse et al involving 69 fetuses with LMs diagnosed in the first trimester suggested that the following were predictors of a poor outcome  :
Nuchal thickness greater than 6.0-6.5 mm
Presence of hydrops fetalis, ultrasonographic abnormalities, or both
Fetal karyotypic abnormalities, ultrasonographic evolution of LM, or both
A study by Sanhal et al found that fetuses with septated LMs had with poor perinatal outcomes. 
What would you like to print?