Enteric duplication cysts in children: varied presentations, varied imaging findings

Enteric duplication cysts (EDCs) are rare congenital anomalies found anywhere along the gastrointestinal tract (GT) from the mouth to the rectum; most commonly in the ileum (33%), followed by the oesophagus (20%), colon (13%), jejunum (10%), stomach (7%) and duodenum (5%) [1‐4].

The incidence is 1:4,500 births, found in 0.2% of all children, with a slight male predominance [3, 5‐7].

EDCs are believed to occur between the 4th and 8th weeks of embryonic development. Their aetiology is still unknown; several theories have been proposed to explain their pathophysiology, but no single hypothesis can justify all duplications, locations and associated anomalies. Split notochord theory is often postulated [8]. The luminal recanalisation theory explains duplications in those portions of the GT that have a solid stage, including the oesophagus, small bowel and colon; nevertheless, it does not explain duplications at other levels. Incomplete or partial twinning theory could explain the colorectal duplications that are associated with duplication of genital and urinary structures. Persistent embryonic diverticula theory suggests that small diverticula, usually transient along the antimesenteric border of the intestinal wall, persist and develop intestinal duplications, although most ECDs are in the mesenteric border. The intrauterine vascular accident theory suggests that gastrointestinal duplications arise from an intrauterine vascular accident during early fetal development and may be a valid explanation for isolated duplication. These different theories lead to think that the origin of EDCs can be multifactorial [1, 2, 4, 9, 10].

Associated anomalies such as spinal defects, cardiac or urinary malformations, are reported with an incidence rate of 16–26%. Other digestive anomalies are present in about 10% of cases. Therefore, once an EDC is found, a search for other anomalies is needed [6, 10‐12].

EDCs must have three characteristics: an epithelial lining containing the mucosa of the alimentary tract, an envelope of smooth muscle, and the cyst must be closely attached to the GT by sharing a common wall (Fig. 1). The mucosal lining does not always correlate with the adjacent gastrointestinal tissue, but the duplications are named according to the part of the GT to which these are intimately attached. Ectopic gastric mucosa is found in 20–30% of these cysts, more frequently in oesophageal and small bowel duplications [13, 14]. Prominent gastric mucosa can also be seen as a polypoid mass covering the base of the cyst, being transmural (Fig. 2) [6]. Ectopic pancreatic mucosa is most common in gastric duplications [2].

Structurally, EDCs can be either cystic or tubular. Spherical cysts are the most common duplications (80%) and typically do not communicate with the adjacent lumen. Tubular duplication cysts (20%) run parallel to the GT, being communicated with it (Fig. 3) [4, 12, 15, 16]. Then, when a duplication cyst is tubular, the connection with GT must be demonstrated for surgical planning [17].

Multiple duplication cysts are rather uncommon (1–7%) [4, 16]. These include multiple EDCs within one segment of the GT or less frequently in two or more segments (Fig. 4) [11, 16, 18, 19].

Atypical EDC is a non-communicating isolated duplication cyst completely separated from the bowel with no communication or shared wall. A vascular insult could have led to the isolation. They are extremely rare [19, 20], especially multiple isolated EDCs, which are even rarer [19].

The size, location, type, mucosal pattern and presence of complications produce different clinical presentations and several imaging findings of the EDCs. Ultrasonography (US) is the most used imaging method for diagnosis of abdominal EDCs. Magnetic resonance (MR) and computed tomography (CT) are utilised for oesophageal EDCs and for helping in difficult surgical approaches.

We review the different forms of presentation of EDCs, showing both typical and atypical image findings with the different imaging techniques. We correlate the imaging findings with the surgical results and the final pathological features.

The intrauterine presentation is increasing, mostly due to the improvement in prenatal screening US, routine second-trimester screening and improved imaging resolution. However, prenatal diagnosis of EDCs is often difficult, and US identifies only 20–30% of them, and sometimes they are discovered by chance (Fig. 5) [21, 22].

The natural history of EDCs is quite variable. The clinical presentation or onset symptoms of these malformations range from infancy and early childhood to adulthood. Almost 70% of EDCs present symptoms within the first year of life and 85% in the second one [3, 10, 14].

The signs and symptoms depend on the type and location of the duplication.

Oral and oesophageal cysts may cause respiratory distress or dysphagia. Retrosternal pain, haemoptysis and infection can occur in case of large cysts with rapid growth (Fig. 6) [6, 23].

Gastric and intestinal duplications may produce nausea, vomiting, abdominal distention or palpable abdominal mass (Fig. 7). Recurrent abdominal pain is one of the most frequent forms of presentation and is usually attributed to high pressure inside the duplication cyst because of the accumulation of secretions. Intussusception is another complication in which the cyst serves as a head point and pain, obstruction or bleeding are possible forms of manifestation. Extrinsic compression of the adjacent bowel is also possible, which causes obstruction. However, the most serious complications are produced if gastric mucosa is present within the cyst, leading to inflammation, bleeding, ulceration and even perforation [6, 9, 13, 14, 24, 25].

Nonetheless, EDCs can sometimes be detected incidentally (Fig. 8).

US is the imaging method of choice in the diagnosis of EDCs; only limited in the evaluation of oesophageal EDCs. Transoesophageal ultrasound might be useful but is not routinely used [26, 27].

Classical findings of uncomplicated EDC include: presence of a cyst in relation to the gut with double-wall or muscular rim sign (gut signature sign), which is caused by inner hyperechoic mucosa and outer hypoechoic smooth muscle layer (muscularis propia) (Figs. 1 and 7). However, the double-wall sign in other cystic lesions (mesenteric cyst, Meckel’s diverticulum or torsioned ovarian cyst) may be seen [1, 2, 11, 24, 28‐30].

New US signs are described according to the characteristics of the EDCs:

US is a dynamic study and allows to visualise the peristalsis of the cyst wall. It appears as a transient change of the shape and contour of the cyst because of a concentric contraction of the cyst wall (Fig. 10) when the transductor stays still on the cyst for a while [2, 27].

Although EDCs are frequently anechoic or hypoechoic, mucinous material or septations can be present without being complicated (Fig. 11) [27].

Complicated EDCs rarely present the classic five layers or double-wall sign. Ectopic rest of pancreatic tissue can produce enzymatic destruction of the mucosa with inflammation, as well as loss of the wall layers showing a hyperaemic thick wall. In such cases, the “Y configuration” sign helps in establishing the correct diagnosis of EDC (Fig. 12) [3, 29, 30]. If ectopic gastric mucosa produces haemorrhage and bleeding, fluid levels or echogenic debris can be seen. When infection occurs, ulceration of mucosa can appear, and internal debris may be seen. The transmural extension can produce important inflammatory changes in the surrounding mesentery fat (Figs. 13 and 14) [3, 7, 24]. Ileal EDC, near the ileocecal valve, can act as intussusception head, showing on US a cystic mass inside the intussusception requiring emergency treatment (Fig. 15) [2].

In case of atypical or isolated EDC, the pseudokidney sign is described when there is a complete loss of typical wall layers because of severe congestion, thus producing a thick hypoechoic rim with a hyperechoic central layer [32].

US prenatal diagnosis of EDCs includes the same signs as postnatal cyst: the double–wall sign and the presence of peristalsis. However, on the prenatal US, the “double wall” is not always seen or can be partial [10, 33, 34], and it may require the differential diagnosis with other cystic lesions such as mesenteric, omental, ovarian and choledochal cysts. If it is possible to demonstrate the presence of peristalsis in the cyst wall, an intestinal origin is probed. MR imaging is suggested to have a supplemental value in the assessment of fetal abdominal cysts (Fig. 16) [10, 35, 36].

CT is not typically performed for evaluation of EDCs due to radiation. CT may depict the location and extension of the cyst, as well as complications, the associated anomalies and anatomical relationship with surrounding structures. At CT, an EDC manifests as a cystic mass with a thin and slightly enhancing wall adjacent to the gastrointestinal wall. A high attenuation inside the cyst may be seen due to haemorrhage or proteinaceous material. A thick enhancing wall, air bubbles inside and cyst-surrounding inflammation may indicate an EDC complicated by infection (Fig. 17) [1, 11, 12, 15].

Like CT, MR is not routinely used as a diagnostic method for EDCs, especially due to sedation requirement. On MR imaging, most duplications have low signal intensity on T1-weighed images and very high intensity on T2-weighted images (Fig. 18). Both CT and MR play a major role prior to surgery in establishing the relationship between the cyst and its adjacent structures [12], and in locations where US presents a limited use, particularly in oesophageal and rectal duplications [1, 2, 6, 12].

The main considerations in the management of EDCs are: the condition of the patient, the location of the cyst, whether it involves one or more anatomic locations, whether its structure is cystic or tubular, and if it is communicated with the true intestinal lumen.

With the widespread availability of antenatal diagnosis, EDCs are often diagnosed prenatally. The optimal time to perform the resection in children with antenatal diagnosis is not defined. These patients should undergo early investigation, followed by early resection even within the first 6 months of life [3, 37, 38].

Treatment of asymptomatic EDCs remains controversial. The clinical behaviour of EDCs is unpredictable. EDCs tend to increase in size gradually and can cause symptoms and important complications that might be fatal, such as obstruction, massive bleeding or even a potential risk for malignant transformation in the adulthood [13, 14, 17, 39].

Early excision is associated with less morbidity and a shorter length of stay compared to excision in symptomatic patients. There are significant post-operative morbidities after resection of complicated EDCs, compared with its elective surgery. Cyst excision alone could be considered, but if there is a communication, sometimes a resection of the adjacent bowel is necessary. It is important to ensure that the cyst is entirely resected because recurrence or malignant changes may occur [40].

Currently, minimally invasive surgery is becoming the elective approach, and most of the cysts can be resected successfully, either thoracoscopically or laparoscopically, as long as an exhaustive imaging diagnosis is available [41].

EDCs are uncommon congenital abnormalities arising anywhere along the GT. Their clinical presentations vary according to the site of duplication; ileum appears as the most commonly involved. Nowadays, antenatal diagnosis is becoming more frequent. US is the method of choice to diagnose gastrointestinal EDCs. Although double-wall US sign in a cyst is the most typical for diagnosis of EDCs, the findings of the five layers sign or the “Y configuration” of the muscular layer are more specific features. Complicated cysts present atypical imaging findings. CT and MR imaging can be required in oesophageal or rectal EDCs for planning complicated surgical approach. Surgery is necessary because of the severe complications they can develop. The diagnosis is confirmed by histological examination.