Differential diagnosis: Bronchogenic cysts, herniated stomach (diaphragmatic hernia, hiatal hernia), gastrointestinal duplication cysts, pericardial, mesothelial, thoracic duct and parathyroid cysts, anterior meningocele, cystic adenomatoid malformation of the lung type 1 (macrocystic), pleuropulmonary blastoma (Type I) and intrathoracic solitary cyst of the liver
Associated anomalies: Include vertebral anomalies, abnormal gastrointestinal connections, and esophageal atresia.
Macroscopic findings: Unilocular or septated thin-walled sacs filled with clear, gray-white, yellow or green viscous or mucoid material, located in the posterior mediastinum close to the esophagus, typically in a retrocardiac position.
Microscopic findings: The most common form of endodermal cyst consists of a simple epithelium resting on a delicate fibrovascular capsule. Microscopically a thick smooth muscle wall with two or three layers is characteristic. Columnar (native state) or low cuboidal epithelium (due to chronic pressure) is evident. Ciliation is a variable feature but many cells contain globules of mucus. Duodenal glands may be present and pancreatic and salivary gland tissues have been described. Enteric cysts have been classified into three groups, according to histological features.
Group A is the simplest type, lined by a single layer of cuboidal or columnar epithelial cells with or without cilia.
Group B cysts include more complex elements of the gastrointestinal tract or tracheobronchial tree, including mucus glands and smooth muscle in their wall.
Group C cysts have ependymal or glial tissue in addition to the elements seen in group B cysts.
Most neurenteric cysts belong to group A. Squamous metaplasia is occasionally encountered.
Treatment: There are reports of intrauterine treatment by thoracentesis or placement of a thoracoamniotic shunt if the cyst appears to cause lung hypoplasia.
Postnatal evolution: Symptoms of respiratory distress become obvious at birth or during the first months of life, neurological symptoms can develop later. The therapy of choice is complete resection of the cyst.,
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