++
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.
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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.
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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
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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.
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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 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 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.
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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.