What is a Pancreatic Pseudocyst
A pancreatic pseudocyst, is a collection of tissue and fluid that forms either in or beside the pancreas. Most often, a pancreatic pseudocyst will develop as a result of pancreatitis (inflammation of the pancreas).
Pancreatic pseudocysts account for approximately 75% of all pancreatic masses.
What Differentiates a Pancreatic Pseudocyst from a True Pancreatic Cyst
A pancreatic pseudocyst is not the same as a true pancreatic cyst. While it looks very similar to a true cyst, it is made from different kinds of tissue – hence the name “pseudo”, which means false.
Both pancreatic pseudocysts and true cysts are made primarily of fluid; however, a true pancreatic cyst is a closed structure with a lining of epithelial cells that separates it from other tissue. A pseudocyst is not closed.
This difference is important because the course of treatment often differs for each condition. Also, some true cysts have a high tendency to develop into cancer. Pancreatic pseudocysts are rarely cancer.
A correct diagnosis relies on the expertise of a subspeciality radiologist with extensive experience in managing pancreatic lesions.
How is a Pancreatic Pseudocyst Cyst Detected?
Some pancreatic pseudocysts are asymptomatic, and are found incidentally during an imaging test for another issue. Others are detected during routine testing for pancreatitis patients. Or, if a pseudocyst grows large, it may cause significant abdominal pain or bloating that leads to an examination.
While an ultrasound or CT are typically good for detecting cysts in the pancreas, further testing is often necessary to distinguish the type of cyst.
It can be particularly difficult to differentiate pseudocysts from cystic neoplasms. Image interpretation from an experienced subspeciality radiologist is crucial for an accurate diagnosis.
Diagnosing a Pancreatic Pseudocyst
Diagnosing a pancreatic pseudocyst can be tricky because they look very similar to other pancreatic lesions. In some cases, especially when a patient has already been diagnosed with pancreatitis, a diagnosis may be confirmed with just a CT scan. In other patients, an MRI may be necessary. If the diagnosis is still unclear, an endoscopic ultrasound may be performed to take a sample of the fluid inside the cyst. This also helps determine malignancy.
Imaging studies that may be helpful in diagnosing a pancreatic pseudocyst include the following:
Ultrasound – Not the study of choice for establishing a diagnosis, but a helpful tool in identifying a cyst or lesion on the pancreas.
CT – A step up from ultrasound, a CT can help further distinguish the type and exact location of the cyst. Follow up imaging may be necessary to determine if the lesion is a true cyst or pseudocyst.
MRI – Helpful in providing a sharper image of the fluid in a pancreatic pseudocyst. Can also be useful in detecting solid components. Good for differentiating between true cysts and a pseudocyst.
Endoscopic Ultrasound – Usually performed as a supplementary test to other imaging exams to help distinguish the type of pancreatic cyst. Helpful in obtaining fluid from the cyst via a fine needle to determine whether or not it’s cancerous. May also play an important role in planning therapy.
Treatment of a Pancreatic Pseudocyst
Many pancreatic pseudocysts will go away on their own. Some, however, may grow too large and cause persistent symptoms, or develop complications, such as infection, that require intervention.
Even if a patient is not experiencing any symptoms, a pseudocyst that becomes larger than six centimeters in size will need to be drained to prevent rupture. A ruptured pancreatic cyst can be life-threatening and requires immediate medical attention.
There are three methods to drain a cyst:
- Endoscopic drainage
- Surgical drainage
- Catheter drainage
Endoscopic drainage is the least invasive option and has the lowest risk of complications.
While, pancreatic pseudocysts are rarely cancer, it is important they are continuously monitored for changes and growth.
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Not sure what a subspecialist is? Learn more with our in-depth article on the importance of getting a second opinion from a subspecialty radiologist.
Dr. Richard Semelka, leading expert in abdominal imaging, has been practicing radiology for over 28 years. He’s written over 16 text-books, 370 peer-reviewed papers, and has over 21,000 research citations in Abdominal Imaging.