a cyst formed by failure of separation of the gastrointestinal tract from the primitive neural crest because of the neural connection with the spinal canal, which may be via a sinus tract or a fibrous band. Neurenteric cysts have a high incidence of associated vertebral anomalies or anterior vertebral defects. Scoliosis is frequent if the vertebral malformations are severe. The cyst may have a dumbell configuration, the differential diagnosis being an anterior meningocele. Complications of neurenteric cysts include sudden increase in size due to haemorrhage from ectopic gastricmucosa, or meningitis. Neurenteric cysts are in the posterior mediastinum. Occasionally they may be transdiaphragmatic.
When the cyst has no communication with the neural tract they are called enteric cysts or duplication cyst. In the chest they are associated with the oesophagus but very rarely communicate with it. Communication with the gastrointestinal tract is more frequent with abdominal duplication cysts.
Neurenteric, enteric cysts and duplications are lined with intestinal epithelium. In the chest it is often oesophageal epithelium. Ectopic gastric mucosa may be present in any site of a duplication. They can bleed suddenly, cause expansion of the cyst and death may occur either from pressure effect on the airways in the chest, or exsanguination. The ectopic mucosa may show increased uptake of technetium pertechnetate. The wall of the cyst contains smooth muscle with a myenteric plexus.
Radiologically, a thoracic cyst is seen as a smooth posterior mediastinal mass which may displace the trachea anteriorly. CT or MRI is required to map them accurately. Rarely, if large enough to displace lung from them, they can be seen on ultrasound. The typical ultrasonic appearance of a duplication cyst anywhere is that of a smooth-walled unilocular cyst with transsonic fluid and an identifiable double layered wall. See duplication cyst, mediastinal mass posterior. On MRI there is high signal on T2
From Medcyclopedia.com
