What is Pancreatic Mucinous Cystadenoma?
Mucinous cystadenoma (MCN) is a type of tumor that produces a substance called mucin and forms cysts. These cysts often begin in the pancreas. Almost half of the cystic tumors in the pancreas are MCNs, with the rest being serous cystadenoma (SCN) or intraductal papillary mucinous neoplasm (IPMN). Both MCNs and IPMNs can form cysts, produce mucin, and possibly become invasive cancer.
MCNs are most commonly found in the body and tail sections of the pancreas, and are often discovered by accident during other medical checks. Women, particularly younger ones without any previous pancreas-related issues, are most likely to have MCNs. The best way to identify an MCN is usually through an MRI or enhanced CT scan, accompanied by an endoscopic ultrasound where fluid from the cyst is collected for testing.
MCNs have a potential to develop into cancer, so doctors usually prefer to remove them surgically. If the cyst has been entirely taken out and it doesn’t show any signs of being cancerous, it’s unlikely to return, and the patient won’t need regular check-ups for it.
What Causes Pancreatic Mucinous Cystadenoma?
The exact starting point of this kind of cancer is still being discussed among scientists. It looks similar to a type of tissue found in the ovaries. There are a couple of ideas about why it happens: it might come from immature tissue being affected by female hormones, or it could happen if primary yolk cells (the most primitive form of cells) implant in the pancreas.
There is some common genetic change that often happens in this type of cancer, mainly in the KRAS gene. Other changes in the SMAD4 and TP53 genes are observed when the cancer becomes more invasive or aggressive.
Risk Factors and Frequency for Pancreatic Mucinous Cystadenoma
Mucinous cystic neoplasms (MCNs) are less common compared to pseudocysts and pancreatic ductal adenocarcinoma. While there’s not a lot of research on how common they are, it’s estimated that MCNs make up 29% of growths in the pancreas that start in cells. Mostly, women are diagnosed with MCNs, typically between the ages of 40 and 50; it’s pretty rare to see MCNs in men. Usually, these growths are found in the body and tail, or the lower parts, of the pancreas.
- Mucinous cystic neoplasms (MCNs) are somewhat rare, especially when compared to pseudocysts and pancreatic ductal adenocarcinoma.
- MCNs make up about 29% of cystic growths in the pancreas that originate from cells.
- They are typically seen in women, and are rarely found in men.
- The average age of diagnosis is between 40 and 50 years old.
- Most MCNs are located in the lower parts of the pancreas, known as the body and tail.
Signs and Symptoms of Pancreatic Mucinous Cystadenoma
Diagnosing medical conditions often requires a combination of a patient’s history and medical imaging to achieve accurate results. It’s very important to rule out conditions like pancreatitis when dealing with MCNs (mucinous cystic neoplasms), which can cause symptoms such as stomach pain, recurring pancreatitis, gastric outlet obstruction, jaundice or loss of weight. Quite often though, these cystic growths are found accidentally during other investigations.
During a physical examination, some patients may be found to have a lump in the upper part of their abdomen.
Testing for Pancreatic Mucinous Cystadenoma
Imaging
Imaging is used to help diagnose a condition called MCNs and to see if there are signs of cancerous changes. Different imaging techniques can be used for this purpose:
1. A transcutaneous ultrasound which uses sound waves to create pictures of the inside of your body, might be helpful in some cases. However, it doesn’t always provide a full picture of the pancreas, especially if it is located deep within the body.
2. A special type of MRI called a magnetic resonance cholangiopancreatography (MRCP) is often favored over a CT scan, as it’s better at showing the insides of your pancreatic ducts and showing any changes. A contrast-enhanced CT scan, which uses a special dye to make your pancreas stand out more clearly, can also provide useful information. It typically shows any changes in the pancreas, for instance, if there are sections that have turned into fluid-filled cysts.
Usually, on an MRI, MCNs will appear as areas with different sizes in the body and tail portion of the pancreas. MCNs contain fluid-filled cavities; in T2-weighted MRI images, these appear very bright. The MRI also shows whether the fluid-filled sections are connected to the pancreatic ducts.
There are certain signs that suggest MCNs might have turned cancerous, including:
1. The wall of the cyst has thickened
2. There’s a solid component or lump inside the cyst.
3. There might be hardened sections (calcification) in the cyst wall.
3. An endoscopic ultrasound (EUS) provides a better view of the cyst wall and checks for any nodules. The EUS can also be used to take some of the cyst fluid for testing. Features that make doctors suspicious include a diameter greater than 3 cm, nodules on the wall, thick and irregular walls, and a blocked pancreatic duct.
4. The usefulness of a particular type of scan called an F-18 FDG positron-emission tomography in diagnosing MCNs is still being studied.
Cystic Fluid
1. Testing the level of a protein called CEA in the cyst fluid can help doctors differentiate between mucinous and non-mucinous cystic growths with 79% accuracy. A high level of CEA in the cyst fluid might also suggest cancer.
2. The fluid that is taken out from the cyst is sent for cytology, a type of lab test that checks for abnormal cells, especially when the imaging results are unable to provide a clear picture.
Treatment Options for Pancreatic Mucinous Cystadenoma
Mucinous cystic neoplasms (MCNs) carry a substantial risk for cancer. The standard treatment for MCNs is surgical removal. The removal of the MCNs is recommended under specific conditions:
– If the MCNs are causing noticeable symptoms, regardless of their size
– If the MCNs are larger than 4.0 cm (almost 1.6 inches)
– If the MCNs show worrying features, irrespective of their size
If the MCN doesn’t show signs of cancer, a special type of operation that spares the spleen or nearby tissue (non-cancer removal) can be performed. This can use minimally invasive techniques such as laparoscopic and robotic-assisted removal of the end portion of the pancreas. These methods are just as effective as traditional surgery in terms of cancer outcomes, but have the extra benefits associated with minimally invasive surgery.
In cases where the MCNs show worrying features that might suggest cancer, a more rigorous cancer removal surgery is necessary. This often involves the removal of the end portion of the pancreas, the spleen, and the nearby lymph nodes.
For people without symptoms whose MCNs are between 3 and 4 cm (about 1.2 to 1.6 inches), treatment should be decided on a case-by-case basis. Doctors will take into account the patient’s age, their surgical risk, and their personal preference. For MCNs smaller than 3 cm, it can be hard to determine their nature, so doctors often recommend continued monitoring.
This monitoring typically involves magnetic resonance imaging (MRI), endoscopic ultrasound (EUS), or a combination of both every six months for the first year. If no changes are detected, imaging can be done every year for as long as the person is deemed fit for surgery.
The American College of Gastroenterology provides guidelines for imaging based on the size of the cyst:
– Less than 1 cm (about 0.4 inches) – MRI in 2 years.
– Between 1-2 cm (about 0.4 to 0.8 inches) – MRI in 1 year.
– Between 2-3 cm (about 0.8 to 1.2 inches) – MRI or EUS in 6 to 12 months.
If during the monitoring period a patient starts showing symptoms like jaundice, acute pancreatitis, an increase in a specific protein in the blood (serum CA 19-9), lumps in the wall of the cyst, or an increase in the cyst’s size, doctors might recommend endoscopic ultrasound with fine-needle aspiration (FNA). FNA is a type of biopsy where a very thin needle is used to gather cells for testing. In these cases, the patient should be also referred to a team of different healthcare professionals for further assessment.
Some treatments, like injecting ethanol or a chemotherapy drug (paclitaxel) into the cyst or radiofrequency ablation (a procedure that uses heat to destroy tissue) have been studied but are not standard care at the moment.
In conclusion, the risk of a patient developing cancer needs to be balanced against the risks of surgery.
What else can Pancreatic Mucinous Cystadenoma be?
When diagnosing MCNs (mucinous cystic neoplasms), doctors need to rule out similar conditions that affect the pancreas. These conditions can also cause cystic lesions which can be confused with MCNs:
- Intraductal papillary mucinous neoplasm (IPMN)
- Serous cystadenoma
- Pancreatic pseudocyst
- Solid pseudopapillary tumor
- Retention cyst
- Simple mucinous cyst
What to expect with Pancreatic Mucinous Cystadenoma
Once the affected area has been entirely removed and no invasive elements are detected under microscopic examination, the outlook is very positive. In fact, the overall chance of survival is 100%, which means that patients generally don’t need any additional check-ups or treatments.
Possible Complications When Diagnosed with Pancreatic Mucinous Cystadenoma
According to various studies, about half of the people who undergo surgery experience some form of health issues. A common problem is the development of pancreatic fistulas that require prolonged drainage. Pancreatic fistulas are tubes formed between the pancreas and the skin to help drain fluid. Most of these fistulas can be managed with surgical drains placed during the operation, although if they linger for over two weeks, an imaging scan of the pancreas using an endoscope might be required. In some cases, a stent may be placed to reduce the draining fluid.
There’s also a risk of bleeding, which depending on the severity, might require either the help of an interventional radiologist or another surgery.
It’s also worth noting that after a distal pancreatectomy, a surgical procedure involving the removal of the body and the tail of the pancreas, up to 20% of patients may develop new-onset diabetes. Additionally, up to 10% of people might develop new-onset diabetes after a pancreaticoduodenectomy, a complex operation to remove the head of the pancreas.
Common Complications:
- Pancreatic fistulas requiring prolonged drainage
- Persistent fistulas needing more complex procedures
- Severe bleeding necessitating intervention
- New-onset diabetes after distal pancreatectomy
- New-onset diabetes after pancreaticoduodenectomy
Preventing Pancreatic Mucinous Cystadenoma
Patients who are having a surgery known as a distal pancreatectomy or pancreaticoduodenectomy to remove an MCN – a type of cyst in the pancreas – may have a 20% chance of developing diabetes afterwards. It’s really important for patients to understand this risk and learn about managing it. However, the good news is that if the cyst removed is confirmed to be benign, or non-cancerous, it’s unlikely to come back and there’s usually no need for ongoing check-ups. On the other hand, if the cyst has some suspicious features that make doctors uncertain, these patients will need regular imaging tests as a follow-up after the surgery.
