Foregut duplication cyst
Foregut duplication cysts are congenital in nature and are sometimes classified under bronchopulmonary foregut malformations. Entities that fall under foregut duplication cysts include:
- bronchogenic cysts
- neurenteric cysts
- other enteric cysts
During differentiation in the third week of fetal development the foregut undergoes dichotomy and by the fourth week a primitive diverticula arises from the ventral part of the cranial foregut. Two laryngotracheal ridges form between the diverticula and dorsal foregut and later fuse together to become laryngotracheal septum. This septum divides the primitive foregut into a dorsal esophagus and the ventral respiratory laryngotracheal tube. The dorsal tube goes on to develop esophagus, stomach, duodenum, liver, gall bladder and the pancreas. The ventral tube forms a primitive lung bud at its caudal end which differentiates by the seventh week to form bronchopulmonary buds and later the lungs by repeated bifurcation and differentiation.
Underlying basis of the foregut and bronchogenic cysts have been hypothesized to be abnormal pinching of the buds from the portion of the foregut destined for the respiratory differentiation. The formation of enteric cysts, duplication cysts and true tubular duplications have been attributed to the various theories including neurentric canals, split notochord, persistent vacoulation theory, accessory lung bud theory, presence of the mucosal diverticula or the faulty separation of the endoderm and notochord, early in the development.