intrathoracic cystic hygroma
description
cystic hygroma is a multiseptated cystic complex which is primarily located in the neck but may extend into the upper thorax. it represents a series of dilated and obstructed jugular lymph sacs which are the product of a failure of the jugular lymphatic systems to drain into the internal jugular vein. it is believed that this condition may also be the result of an abnormal sequestration of lymphatic tissue in early embryonic life and its failure to join the normal lymphatic channels.
diagnosis
the distinctive features of cystic hygroma as evidenced by the presence of a multiseptated cystic neck lesion with intrathoracic extension simplifies the diagnosis. anomalies including congenital heart defects, cleft lip, and neural tube defects have rarely been described in association with lymphangioma but there are no recognised associated chromosomal or genetic syndromes.
differential diagnosis
several congenital thoracic malformations present with cystic intrathoracic lesions. these include diaphragmatic hernia, cystic adenomatoid malformations, bronchogenic cyst and mediastinal teratoma. the feature that distinguishes a cystic hygroma/congenital lymphangiectasia from each of these is the presence of the multiseptated cystic mass extending into the neck. other specific differentiating features of these conditions are: diaphragmatic hernia – the presence of abdominal contents in the thorax and the demonstration of a diaphragmatic defect. cystic adenomatoid malformation – the cysts are present in lung tissue as opposed to their extrapulmonary origin in cystic hygroma. intrathoracic teratoma – solid and cystic areas are usually present in this intrathoracic lesion. bronchogenic cysts – usually a simple intrapulmonary or mediastinal cyst with no extrapulmonary cystic lesion.
sonographic features
multiseptated cystic mass in the region of the posterior neck with extension into the chest growth of cysts in the chest may compress the lung, oesophagus and vascular structures fetal chest may appear smaller than expected pleural effusions, pericardial effusion, ascites and polyhydromnios may be present.