Lymphatic malformations were first described by Redenbacher (1928). Cystic hygroma is one such malformation.
Two theories have been proposed.
Pathology:They consist of an aggregation of cysts lined by a single layer of flattened endothelium,filled with lymph,fetal fat and cholesterol crystals.
Classification: Landing and Farber’s (1956)
When diagnosed by prenatal ultrasound,they are frequently associated With chromosomal anomalies. Fetuses with septated cystic hygromas are more commonly associated with turner’s syndrome,more likely to develop hydrops and hence have a poorer prognosis whereas fetuses with non septated cystic hygromas are usually associated with Down’s syndrome and have a better prognosis. Other associations include congenital glaucoma, Klippel-Trenaunay syndrome, lymphangiogenic macroglossia and diaphragmatic hernia (Freyn’s syndrome). 60 % occur at birth and 90 % by 2 years. Equal sex incidence except for inguinal hygromas which are five times more common in males.
Usual sites include neck, cheek, axilla, groin, mediastinum and the retroperitoneum.Majority of those in the neck occur in the posterior triangle. Those in the anterior triangle are often associated with intraoral lymphangioma and are the ones likely to produce airway compromise. Mediastinal extension is noted in only 10 % of cases. These swellings are softly cystic, partially compressible (as they are multiloculated) and brilliantly translucent (unless intracystic haemorrhage has occurred).
Diagnosis is usually made clinically and investigations such as chest X-ray, CT-scan and MRI are required only to determine the extent of involvement.
The major differential diagnosis is branchial cyst. Treatment is generally recommended because of the risks of