Chapter 401. Duplications and Cysts

Enteric duplications and mesenteric, omental, and retroperitoneal cysts are rare congenital anomalies. Most are recognized by the age of 2 years. Enteric duplications can occur anywhere in the gastrointestinal tract. Duplications and cysts can present in various fashions from being asymptomatic and an incidental finding causing obstruction, bleeding, or inflammation. Surgery is indicated in all instances to prevent or treat these complications. The surgical management can vary significantly depending on the location as well as the degree of involvement of adjacent structure, in particular the intestine.

Epidemiology

Enteric duplications occur sporadically without any apparent genetic predisposition. The reported incidence of enteric duplications is 0.02%.1 Enteric duplications are commonly associated with vertebral anomalies such as bifid, fused, or missing vertebrae.2 When associated with vertebral anomalies, enteric duplications may communicate with the spinal canal and are termed neuroenteric cysts. Thoracic duplications are more common in the presence of esophageal anomalies, and duplications of the small intestine are commonly identified in association with jejunoileal atresia. Colonic duplications are frequently associated with genitourinary anomalies.3 Multiple duplications are present in 10% to 20% of cases.

Pathophysiology

Enteric duplications are defined by the following three characteristics: (1) the presence of smooth muscle coat, (2) an intimate association with the alimentary tract (often sharing a common wall), and (3) an inner lining of intestinal epithelium. The incidence of enteric duplications by anatomic location is shown in Table 401-1. While a duplication may be identified anywhere from the mouth to the anus, the most common location is in the distal ileum. Duplications can by cystic or tubular (eFig. 401.1). Some traverse the diaphragm from the chest into the abdomen. Ectopic mucosa, most commonly gastric, is identified in up to a third of duplication cysts. Less commonly, the duplication may communicate with adjacent bowel.4 The abnormal embryogenesis that leads to an intestinal duplication is controversial. Because of the frequent association with the spinal canal the split notochord syndrome was proposed to explain neuroenteric cysts (eFig. 401.2). Others have postulated duplications arise as a consequence of failed regression of embryonic diverticula or aberrant recanalization of the solid stage. Environmental stressors such as hypoxia, trauma, and vascular insufficiency have all been proposed as causative factors. Lastly, the development of colorectal duplications in association with urogenital duplications has been attributed to partial or abortive twinning.4

Clinical Features and Diagnosis

The presentation of enteric duplications depends on its location and type. Increasingly, duplications are identified on prenatal ultrasonography.5 Regardless of location, the most common presenting symptoms are attributable to obstruction, inflammation, or bleeding.

Cervical Duplications

Cervical duplications are rare. The majority present before the age of 1, and the most common presenting symptom is obstruction with a mass effect on adjacent structure. Both respiratory distress and dysphagia have been described with cervical duplications. Endotracheal intubation on occasion may be necessary to provide an adequate airway. Cervical duplications tend to be cystic and do not communicate with the esophagus. A palpable mass may be obvious on exam. Computed tomography (CT), magnetic resonance imaging (MRI), or ultrasonography are often useful to differentiate an enteric duplication from other neck masses. The classic appearance of an enteric cyst on diagnostic imaging is that of a fluid-filled cystic structure with a 2-layered wall corresponding to the inner layer of mucosa and outer layer of smooth muscle. Axial imaging with CT or MRI is often helpful in determining the cyst’s relationship to adjacent structures.

Thoracic Duplications

Thoracic duplications, although more common than cervical, represent less than 20% of duplications.6 Thoracic duplications are more commonly associated with and communicate with the spinal column, the aforementioned neuorenteric cyst. In addition, thoracic enteric duplications may extend down through the diaphragm and truly be thoracoabdominal. Both cystic and tubular duplications are found in the chest. Lastly, thoracic duplications are associated with abdominal enteric duplications in as many as one third of cases.4 Presenting symptoms can vary with age. Respiratory distress occurs more often in newborns and infants as the duplication compresses the adjacent airway. Older children may present with bleeding or inflammation from ulceration. Often, thoracic duplications are first recognized incidentally on plain chest radiography as an asymptomatic posterior mediastinal mass. After plain chest radiography, chest and possibly abdominal CT scan is useful to define the anatomy. If a question of communication with the spinal column exists, MRI is superior to CT in defining this relationship.

Gastric Duplications

Gastric duplications most commonly present in infancy with bleeding, perforation, or failure to thrive due to obstructive symptoms. Gastric duplications tend to be cystic, are located along the greater curvature, and do not communicate with the stomach. An upper gastrointestinal examination with contrast will often show obstruction or extrinsic compression of the stomach. If located at the pylorus, this may be confused with pyloric stenosis or pyloric atresia. The classic appearance on abdominal ultrasonography and CT is a cystic mass with a 2-layered wall.

Duodenal Duplications

Duodenal duplications are most often cystic and located in the second and third portions of the duodenum along the posterior medial aspect of the duodenum. Only occasionally will duodenal duplications communicate with the adjacent duodenum. Symptoms are typically obstructive in nature and are often intermittent. Diagnosis can be difficult given the intermittent nature of the symptoms. Therefore, duodenal duplications are often not diagnosed until childhood. However, prenatal diagnosis of cystic abdominal masses is increasingly more common. Duodenal duplication must be differentiated from other cystic upper abdominal masses, in particular, choledochal cysts, hepatic cysts, pancreatic cysts, and pseudocysts. An upper gastrointestinal examination may be helpful in suggesting external compression and partial obstruction of the duodenum. Most often an ultrasound and/or contrast-enhanced computed tomography scan is necessary to demonstrate a cystic, thick-walled mass and provide anatomic relationships to other adjacent organs.

Small Intestinal Duplications

Small intestine duplications represent the majority of duplications. The ileocecal region is the most common location. Duplications of the small intestine can be either cystic or tubular and vary significantly in size; occasionally, tubular duplications extend over a long length of the small intestine. Duplications are most commonly located on the mesenteric side of the bowel wall, in contrast to a diverticulum. Symptoms are most commonly obstructive, often leading to intussusception. Less commonly, duplications of the small intestine are associated with gastric epithelium promoting ulcerations and intestinal bleeding (its mesenteric location differentiates it from a Meckel diverticulum).

Colon and Rectal Duplications

Large intestine and rectal duplications represent the second most common site for duplications. Similar to duplications of the small intestine, duplications of the large intestine are extremely heterogeneous. Both cystic and tubular duplications occur, and duplications can be either quite small or extend over the entire length of the large intestine. Often, duplications of the large intestine are associated with anomalous development of the lower spine, pelvis, and urogenital system. The most common presenting symptoms are obstructive, although this can be acute or chronic. Similar to duplications elsewhere, gastric mucosa within the duplications can lead to ulceration and bleeding. Rectal duplications can often be felt as a mass on rectal exam, performed in the setting of chronic constipation.

Abdominal Cysts

Abdominal cysts include cysts arising from the intestinal mesentery, omentum, and retroperitoneum. While abdominal cysts are uncommon, their true incidence may be underreported due to the fact that many can be asymptomatic and therefore undiscovered. True congenital cysts are benign and can be unilocular or multilocular. They can be confused with pseudocysts of the pancreas or from previous ventriculoperitoneal shunts. Radiographically, they can appear to be similar to cysts of the ovary; intestinal duplications; and renal, hepatic, or biliary cysts. The cyst wall is thin and is lined with endothelial cells. Most often the cyst is filled with serous fluid, although it may occasionally contain lymph. As a consequence of more routine prenatal imaging and the increased use of the computed tomography scan, many abdominal cysts are discovered incidentally.

Treatment

Optimal treatment of an enteric duplications cyst includes complete resection. Occasionally, complete resection would require unacceptable removal of adjacent organs. In such instances ablation or striping of the mucosal surface on the common wall of the duplication can be performed. For long, tubular duplications of the small intestine, resection will require removal of an unacceptable length of normal intestine. In these instances, drainage of the duplication into adjacent normal bowel through an opening in the common wall is the treatment of choice. If gastric mucosa is present within the duplication, it should be stripped as well to prevent bleeding. Complications from surgical resection are infrequent. The long-term outcome following resection of duplications and abdominal cysts is generally excellent.