bronchogenic cyst
description
this is a form of intrathoracic foregut malformation which results from abnormal budding of the ventral diverticulum of the foregut between day 26 and day 40 of intrauterine life. it may either be mediastinal or intrapulmonary in location and is lined by ciliated columnar epithelium which is commonly connected to the tracheobronchial tree.
diagnosis
the diagnosis is suspected when an anechoic, unilocular, simple intrapulmonary or mediastinal mass is seen. bronchogenic cysts typically occur as isolated abnormalities without associated anomalies and not in association with any recognised chromosomal or genetic conditions. there have been 2 case reports of associated truncus arteriosus, oesophageal atresia, myelomeningocele and multicystic kidneys in one fetus, and another with associated diaphragmatic hernia. in one series (ramenofsky), 25% of cases had associated anomalies, including one case with isolated dextrocardia, another with down syndrome and congenital heart disease and another with an accessory lung lobe.
differential diagnosis
- oesophageal cyst duplication – this is also a simple unilocular cyst which is always extrapulmonary and usually lies either within or close to the oesophageal wall.
- sonographic differentiation from the mediastinal form of bronchogenic cyst is difficult.
sonographic features
well defined, unilocular, simple, anechoic intrapulmonary or mediastinal cyst intrapleural cyst commonly seen in the left lower lobe and may be adjacent to the mediastinum mediastinal shift may be present.
associated syndromes