Pancreatic Cysts

Neoplastic Cysts

Papillary neoplastic cysts, which are rare in childhood, should be assumed to cause cancer. Only by looking at the cyst under the microscope after surgery can doctors tell if the cyst is cancerous. They are easily ruptured, and the fluid inside the cyst is extremely irritating to the inside of the belly.

Pancreatic Pseudocysts

Pancreatic pseudocysts are abnormal swellings that look like cysts (Figure 1).

They usually happen after new inflammation of the pancreas or injury. Pancreatic pseudocysts make up more than 75% of cystic problems of the pancreas; they are located most often behind the stomach. The wall of the cyst is made of inflammatory tissue which can be flimsy or tough, and the lining lacks the normal cells present in true cysts.

A pseudocyst may or may not connect with the pancreatic drainage system, but when it does, pancreatic enzyme (amylase) levels frequently exceed 3000 U/L.

These cysts are usually one big cyst, and they can hold more than 1 liter of fluid. 70% of these cysts may result from injuries. Pseudocysts occasionally occur after pancreatitis caused by unknown factors, and rarely a stone stuck in the main bile tube, a duplication cyst, or mumps may cause a pseudocyst to form.

Patients with pancreatic pseudocysts often were injured by a blow to the belly or had an illness resembling pancreatitis weeks to months earlier. Upper belly pain and loss of appetite progressing to nausea, vomiting, and weight loss often follow. Eventually one is able to feel a round mass in the upper part of the belly.

The growing pseudocyst may push the stomach up and forward and the colon down and forward. A portion of the first part of the small intestine may be narrowed or blocked. Increased fluid inside the belly may develop with large increases in pancreatic enzyme levels. Abdominal ultrasound and CT are generally diagnostic (Figure 1).

Small cysts not interfering with bowel function often can be followed with repeated ultrasound or CT until they ultimately disappear. For acute pseudocysts resulting from injuries, needle drainage through the skin sometimes is effective. Complications from untreated large pseudocysts may include bleeding, infection, rupture with severe belly pain, and blockage of bowel, pancreatic, or bile tube function.

Proper treatment depends mainly on the age of the cyst and the strength and thickness of the cyst wall on CT. Of the patients with moderately severe acute pancreatitis, including pancreatitis caused by injuries, who get pseudocysts, 50% go away on their own within 3 to 4 weeks when treated without surgery, unless infection occurs.

When a pseudocyst has achieved chronic status, it is not likely to go away on its own, and continued medical treatment without surgery may lead to complications. Cysts only in the tail (left side) of the pancreas may be removed by removing that end of the pancreas without removing the spleen.

A large pseudocyst in the middle part (body) of the pancreas, pushing against the stomach, is best treated by draining the cyst into the stomach either by using telescopic equipment placed through the patient’s mouth into their stomach or by surgery. The opening through the back wall of the stomach into the cyst should be made big enough so that it will not close before the cyst has collapsed completely. Bleeding after surgery can occur.

For pseudocysts of the head of the pancreas or for cysts in the body that are not right next to the stomach, drainage into the intestine is better. X-ray dye studies after surgery may show the cyst filled with dye for weeks or months until the cyst cavity is no longer present. There are some reports of successful needle drainage through the skin of chronic pseudocysts, especially for pancreatitis caused by injuries when the pseudocyst does not have a known connection with the pancreatic duct (tube) system.

A pancreatic pseudocyst that goes into the chest is a rare problem that may show up as an upper belly mass with either (1) fluid in the chest outside of the lung with a high enzyme (amylase) level or (2) a chest mass. CT scan may show the whole pseudocyst above and below the diaphragm.

The most successful surgery in these patients has been drainage of the major pseudocyst into the intestine. Drainage inside the chest of these pseudocysts commonly leads to the same problem again. Occasionally a cyst that is only inside the chest that has been there since birth may contain pancreas tissue. In these cases, the cyst should be removed through the chest.

SUGGESTED READING

Nealon WH, Walser E: Main pancreatic ductal anatomy can direct choice of modality for treating pancreatic pseudocysts (surgery versus percutaneous drainage). Ann Surg 235: 751-758, 2002.
This article shows how pancreatic ductal anatomy in patients with complicated pancreatitis should guide the selection of treatment.

Article and graphics adapted from O'Neill: Principles of Pediatric Surgery. © 2003, Elsevier.