What is Duplication Cyst?
Duplication cysts, sometimes referred to as alimentary tract duplications, are a type of birth defect in the digestive system. The exact cause of these cysts remains unknown, but several theories have been proposed. They are quite rare, affecting 1 in every 4500 newborns, and slightly more common in males. Most of the time, symptoms of these cysts are seen within the first two years of a child’s life. Despite advancements in pre-birth imaging, it’s only possible to diagnose 20% to 30% of these cysts through ultrasound scans before the baby is born.
The diagnosis of these cysts can be complex due to the variation in their location, size, and the presence of different types of mucous tissue. However, a gut signature sign on an ultrasound is a clear indicator of a duplication cyst. In children with this cyst, surgery is the definite treatment. After successful surgery, long-term results are generally very good.
What Causes Duplication Cyst?
The exact cause of alimentary tract duplications, or the development of duplicate parts in the digestive tract, remains unknown, but they’re believed to develop due to abnormalities during the 4th to 8th weeks of pregnancy. Several theories aim to explain how these duplications occur.
The first theory, the split notochord theory, suggests that these duplications result from improper separation of the developing central part of the embryo and its surrounding cells. This is often cited as an explanation for any spinal abnormalities that occur alongside the duplications.
The recanalization theory argues that errors in the process where the previously blocked gut opens up again during development are to blame for the duplications. However, this doesn’t account for duplications in areas that don’t undergo this reopen process as they grow.
The embryonic diverticula theory suggests that some small pouches exist in the growing embryo’s digestive system. If one remains, it grows with the rest of the digestive tract and contributes to the development of the duplications. While this gives a reasonable explanation for most duplication cases, it can’t explain why certain types of cells appear in these duplicated sections.
The partial or abortive twinning theory posits that these duplications occur due to an incomplete splitting of the digestive tract, similar to the process that results in twins. Even though this association explains some of the doubling anomalies in the urinary and reproductive tracts associated with digestive tract duplications, it can’t account for duplications that appear in other areas.
Risk Factors and Frequency for Duplication Cyst
Duplications in the alimentary tract, also known as the digestive tract, are relatively rare, occurring in 1 out of every 4500 births. These duplications are very slightly more common in males. They are usually found in children, often showing symptoms within the first two years of life. However, sometimes they may not become noticeable until adulthood.
- Duplications in the alimentary tract occur in 1 out of every 4500 births.
- They’re slightly more common in males.
- Most often, these duplications are found in children and show symptoms within the first 2 years.
- However, they can sometimes only become noticeable in adulthood.
Signs and Symptoms of Duplication Cyst
Alimentary tract duplications are common in childhood. These are extra parts of the gut (like the stomach or intestines) that are present from birth. The kind of symptoms a child experiences depend on many factors: the location of the extra part, the type (cystic or tubular), and whether there’s any extra stomach or pancreas tissue (ectopic mucosa).
Kids with cystic duplications normally show symptoms like abdominal pain, though sometimes these duplications can be discovered by accident. Children with tubular duplications that are partially connected to the rest of the bowel present different symptoms. They may have chronic constipation because the doubled part can collect, or load, intestinal contents in a dead-end loop. If the duplicated part contains extra stomach or pancreas tissue, the child might experience abdominal pain and gastrointestinal bleeding. This happens because the duplication can cause ulceration (sores) and bleeding from the healthy adjacent bowel.
Gut duplications are grouped into three categories based on their location: foregut (near the top), midgut (middle), and hindgut (near the end). Symptoms can differ for each case:
- Foregut duplication: Symptoms mostly include difficulty swallowing (dysphagia), vomiting, stomach pain, and upper gastrointestinal bleeding. The duplication can cause compression on the surrounding structures, resulting in symptoms like a large neck mass, stridor (a wheezing sound when breathing), shortness of breath, and cough. In some cases, these duplications can be detected before birth on a routine ultrasound.
- Midgut duplication: Children may experience stomach pain, a palpable mass, nausea, and vomiting. They may also show signs of upper gastrointestinal bleeding if the duplication contains heterotopic mucosa (extra stomach or pancreas tissue). Acute abdominal pain due to intussusception or volvulus (twisting of the gut) can also occur.
- Hindgut duplication: Similar to small bowel duplication, hindgut duplication might involve stomach pain, a palpable mass, vomiting, gastrointestinal bleeding, or signs of intestinal obstruction. Although they are rare, malignant transformations (cancer) has been observed in these cysts. Rectal duplications can sometimes cause distinct clinical presentations, including presacral masses or an anal opening that is not formed properly resulting in a rectovaginal fistula.
Testing for Duplication Cyst
An ultrasound examination may detect certain types of developmental anomalies in unborn babies, but its effectiveness is limited with a sensitivity rate of only 20% to 30%. As these conditions can present in various ways, diagnostic imaging plays a vital role.
An abdominal ultrasound can reveal a typical five-layered cyst wall that alternates between looking lighter and darker. This pattern is called the ‘gut signature sign’ and can confirm the presence of a duplication along the digestive tract. However, ultrasound has difficulty detecting these anomalies inside the chest cavity. If necessary, a specialised type of ultrasound (transesophageal ultrasound or TEE) can be used, but this equipment isn’t readily available in all regions, particularly in developing countries. In these situations, contrast-enhanced computed tomography (CECT) can help by locating these tissue duplications. On a CECT, the duplications appear as masses that show less intensity, with a brighter rim around them.
Similar issues can arise when diagnosing duplication cysts deep within the pelvic cavity. In these cases, magnetic resonance imaging (MRI) provides clearer images of the body’s cross-sections, aiding in diagnosing the cysts.
A technetium-99m pertechnetate scan is another tool doctors use to identify whether the cyst contains misplaced stomach tissue. While this knowledge may not alter the treatment plan, it can reveal the presence of multiple related issues. It’s helpful to know that some types of duplication cysts, like those in the lungs and rectum, don’t generally show up on this specific scan, so it can be skipped in these instances.
Treatment Options for Duplication Cyst
The definite solution for treating a duplication cyst is through a surgical procedure. The type of surgery performed relies on the surgeon’s expertise, and can be either an open surgery (called a laparotomy or thoracotomy) or a less invasive process (known as laparoscopic or thoracoscopic).
How to manage lesions or abnormalities detected before birth or by chance:
These abnormalities can be spotted during prenatal ultrasounds and early surgery is advised. Surgery is not just recommended due to the risk of the abnormalities turning into a tumor, but also because several of these cases, if left unmanaged, can develop complications like intussusception, volvulus, and hemorrhage.
How to manage cases with symptoms:
Immediate surgery is suggested in all situations where symptoms are present.
Dealing with duplication cysts in the esophagus:
These require a specific operation called posterolateral thoracotomy. These cysts can be removed by a simple cut and removal. In the case of large cysts, first shrinking the cyst may make it easier to remove.
Addressing stomach and intestinal duplication cysts:
In most cases, a type of open surgery called laparotomy is used to remove the cyst. For some specific types of duplications or those deeply connected with the bowel wall, the removal and reconnection of the organ might be needed. More complex or multiple duplications in the small intestine can be treated with a procedure that strips the mucus lining or a technique known as Wrenn’s procedure. A similar approach, named Soper’s procedure, can be used for long duplications in the large intestine. To help expel waste, a communication path is created between the blind-ended duplication and the healthy bowel.
Managing rectal duplication cysts:
These cysts might appear as bubbly masses before the sacral bone or a hole between the rectum and vagina that shouldn’t be there. Hence, a posterior sagittal or abdominoperineal technique is needed to remove the cyst.
Understanding special cases:
Simultaneous cysts in the chest and abdomen:
In 10-15% of cases, cysts might appear at the same time in both areas. If this happens, it is best to remove the cyst that is causing symptoms first. But if both are causing problems, the one in the chest is typically removed first to minimize issues related to anesthesia. However, remember that with modern anesthesia, both cysts can be removed in one single operation. But, this could mean more side effects, the need for a breathing machine after surgery, a longer need for pain relief, and an extensive hospital stay, etc.
Dealing with Neurenteric cysts:
It’s crucial to perform a proper evaluation using a spine MRI and plan the surgery with a neurosurgery team. If the cyst significantly involves the spinal column, it should be removed first.
What else can Duplication Cyst be?
When trying to diagnose a duplication cyst, doctors might consider other conditions that have similar symptoms such as:
- Meckel’s diverticulum: This condition affects the same age group and shows similar symptoms as a duplication cyst, like stomach pain and bleeding from the upper digestive tract. A specific scan can show positive results for both conditions, but a definitive diagnosis is only possible through further exploration. The main difference is the location. Duplication cysts are found on the mesenteric side (towards the middle of the abdomen), while Meckel’s diverticulum is on the anti-mesenteric (opposite) side.
- Congenital segmental intestinal dilatation: This condition causes the small or large intestine to dilate or expand 3 to 4 times in certain sections. Both this condition and duplication cysts can show dilation, but the difference is that segmental dilatation doesn’t have any cystic structure near the normal bowel. The treatment for both conditions, however, is similar.
- Other intraabdominal cystic lesions: These include cysts in the mesenteric area, the omental area (a fatty sheet of tissue), the choledochal area (in the bile duct), and the ovaries.
- Presacral masses: Rectal duplication cysts can show similar signs as other masses located in front of the sacrum (presacral) area, including sacrococcygeal teratoma, anterior meningocele (a bulge of the membrane that covers the spinal cord), and dermoid cysts. An MRI scan and specific biochemical tests such as alpha-fetoprotein assay usually help confirm the diagnosis.
- Other intrathoracic cysts: These cysts, including pericardial and thymic cysts, can be considered as possible diagnoses when dealing with duplication cysts. The major difference is their location: while duplication cysts are found in the rear of the mediastinum (the space between the lungs), pericardial cysts and thymic cysts are found in the middle and front of the mediastinum, respectively.
It’s important for doctors to be aware of these possible conditions and to carry out the necessary tests to accurately diagnose the issue.
What to expect with Duplication Cyst
Cysts in the digestive tract are often found in children. In most cases, these cysts need to be removed with surgery. However, some cases may demand more complicated surgeries. On a positive note, after the best-suited surgery, long-term outcomes are generally very good.
Possible Complications When Diagnosed with Duplication Cyst
If a diagnosis or surgery is delayed, complications can occur. These include issues such as volvulus (a twisting of the intestine causing a blockage), intussusception (when one part of the intestine slides into another part), frequent bleeding, and an increased risk of developing cancerous changes. Cases have also been reported where large duplication cysts (cystic masses that resemble a normal organ) have ruptured.
Post-surgery complications are common to most abdominal operations. These can range from a local wound infection to an anastomotic leak (a leak between two sewn fragments of intestine) and adhesive obstruction (blockage caused by scarring after surgery).
Key Complications:
- Volvulus – twisting of the intestine
- Intussusception – one part of the intestine slides into another
- Frequent bleeding
- Risk of developing cancerous changes
- Rupture of large duplication cysts
- Local wound infection
- Anastomotic leak – a leak from the site where intestine was stitched together
- Adhesive obstruction – blockage caused by scarring after surgery
Preventing Duplication Cyst
It’s important to educate parents about the different methods of surgical treatment. In situations where a problem is identified before birth, the couple needs to be informed about the symptoms their baby might experience after birth, the various ways of diagnosing these symptoms, and how they can be managed. Parents also need to be made aware of the potential complications that might arise from surgery.
