Foregut Duplications

Abstract

Foregut duplications are cystic or tubular malformations that arise from the cephalic segment of the primitive gastrointestinal tube. The foregut is an embryonic structure from which several respiratory and digestive structures originate: trachea, lungs, pharynx, esophagus, stomach, proximal duodenum, the parenchyma of the liver and pancreas. Most of these structures arise from the original tube as simple buds that then branch repeatedly. Foregut duplications are thought to be the result of abnormal additional buds that do not undergo a branching process and remain as simple blind cysts. They can occur at any level of the foregut, from the pharynx to the duodenum, but the vast majority develops from the tracheobronchial tree and the esophagus.

Appendices

Summary Points

Foregut duplications are aberrant cystic or tubular malformations that arise from the cephalic segment of the primitive gastrointestinal tube. The majority are located in the thorax.

The primitive gastrointestinal tube, or foregut, is an embryonic structure from which several respiratory and digestive structures originate: trachea, lungs, pharynx, esophagus, stomach, proximal duodenum, and the parenchyma of the liver and pancreas.

The term “foregut duplication” comprises a wide group of entities that share a common embryologic pathophysiology. The most common ones are esophageal duplications, duodenal duplications, gastric duplications and bronchogenic cysts.

The organ of origin (usually determined by the type of mucosa lining the inner surface of the duplication) does not always correlate with the location of the malformation.

The majority is asymptomatic, and found on imaging studies obtained for other reasons. Symptoms are generally associated with a space-occupying effect and the compression of adjacent organs.

All foregut duplications must be resected. If they produce symptoms, the resection is intended to relieve them. If they are asymptomatic, they must be resected due to the high likelihood of becoming symptomatic, due to the potential for infections, to allow for compensatory lung growth, and due to the potential for malignant degeneration.

Editor’s Comment

In clinical practice, foregut duplications include bronchogenic cysts and esophageal duplications. Nearly all can and should be excised thoracoscopically. Exceptions include some that communicate with or involve a long segment of the esophagus or airway, and those that were infected at one time and therefore likely to be extremely difficult to excise easily. As with all operations performed in the mediastinum, careful attention to avoid injury to adjacent structures (especially the phrenic and vagus nerves and the thoracic duct) is paramount, though fortunately these lesions typically separate from all important structures by gentle blunt dissection, until, of course, you reach the organ of origin, when patience and meticulous technique are critical. Spillage of the sterile contents of the cyst does not appear to increase the risk of recurrence or infection and is often performed deliberately to aid in the dissection of a large cyst or to remove it from the chest. When dealing with an especially adherent or fibrotic cyst wall, it is acceptable to enter the lumen and to strip the mucosa completely, leaving the fibrotic wall behind, but it is especially important to identify and repair communication with the lumen in these cases. Except when a lumen has been breached or frank infection is present, routine placement of a drains or chest tube is generally unnecessary.

Long, tubular thoraco-abdominal esophageal duplications can also be approached thoracoscopically, by mobilizing the thoracic portion first and then completing the dissection in the abdomen by laparoscopy or laparotomy. Extensive preoperative imaging with three-dimensional reconstruction is very useful in planning these challenging operations.

Differential Diagnosis

• Pericardial cyst

• Lymphatic malformations

• Anterior myelomeningocele

• Neuroenteric cyst

• Cystic congenital adenomatoid malformation

• Cystic teratoma

• Hydatid cyst

Diagnostic Studies

• Plain chest radiograph

• Esophagogram

• Computed tomography scan

• Echocardiogram

• Magnetic resonance imaging

Parental Preparation

• Possible opening of the esophagus

• Possible opening of the major airway

• In general, satisfactory outcome

Preoperative Preparation

• NPO/IV hydration

• Type and screen

• Blood on hold

• Informed consent

Technical Points

• Open or minimally invasive approach are feasible

• Thorough examination of the thoracic cavity

• Gentle blunt dissection of the duplication

• Careful dissection of the plane between the duplication and then organ of origin

• Careful search for a patent communication with the esophagus or airway