Cystic Neoplasms of the Pancreas

There are several types of cystic tumors or neoplasms of the pancreas, each with malignant potential that varies from nearly zero to up to 70% depending on the type. Distinguishing a neoplasm from a pseudocyst and distinguishing among the different types of neoplasm is often straightforward, but at times can be challenging.

Serous Cystadenoma

Although this type of cystic neoplasm is usually asymptomatic, it can cause pain. They can grow to be quite large, and some patients will have an abdominal mass easily observed upon physical examination. CT scan will reveal a cystic mass with a central scar and often with calcification. On endoscopic ultrasound, the tumor will be described as 'microcystic' or as having a 'honeycomb' appearance. Often it is difficult to remove the fluid from these cysts, because each individual compartment of the honeycomb is small. However, if fluid is sent for analysis, the CEA and amylase levels should be close to zero. Biopsy sent for cytology is generally non-diagnostic for these lesions.

Serous cystadenomas are benign tumors that harbor little if any potential to develop into a malignancy. For this reason, most centers (ours included) recommend observation. Surgery is indicated if these cysts become symptomatic or very large. Also, some patients opt to undergo surgical removal because of diagnostic uncertainty.

Mucinous Cystadenoma

Most mucinous cystadenomas are asymptomatic, but they can cause pain. These tumors are most often seen in the tail of the pancreas of young women. Imaging will reveal a unilocular cyst (a cysts containing only one compartment), or one with a few septations (divisions causing multiple compartments within the cyst). If fluid is removed and sent for biochemical analysis (obtained by endoscopic ultrasound), the CEA will be high (over 192 ng/mL) and the amylase level will be low, because these cysts do not communicate with the pancreatic ductal system. Theses cysts do have the potential to become malignant (mucinous cystadenocarcinoma). Because these cysts are generally identified in young and otherwise healthy women and because of their malignant potential, the recommendation is for surgical removal. Because most of these cysts are found in the tail of the pancreas, most of these patients will need a distal pancreatectomy, which can be performed by a variety of techniques.

Intraductal Papillary Mucinous Neoplasm of the Pancreas (IPMN)

First described in the mid 1980's, IPMN is a cystic neoplasm of the pancreas that is being diagnosed with increasing frequency as an incidental finding on an MRI or CT scan of the abdomen done for some other indication. IPMN is a slow growing tumor that has malignant potential. Two distinct variants have been described: Main duct and Branch duct.

Main Duct IPMN

This variant of the disease may be asymptomatic, but often mirrors signs and symptoms of acute pancreatitis. On endoscopic evaluation, the ampulla of Vater (where the pancreatic duct meets the bile duct) is often described as having a "fishmouth" appearance, which is mucinous material being extruded from the pancreatic duct into the small intestine. It is the high viscosity of this mucinous fluid that obstructs the pancreatic duct and causes pancreatitis. A segment of the main pancreatic duct may be affected, or the disease may involve the entire main pancreatic duct. The rate of malignancy is very high (up to 70% in reported surgical series). For this reason, in medically fit patients, the recommendation is for surgical removal of the affected portion of the pancreas. If the entire duct is involved, the patient will need to have the entire pancreas removed (total pancreatectomy).

Branch Duct IPMN

Branch duct IPMN's are cystic neoplasms of the pancreas that have malignant potential. Many are asymptomatic and are identified on imaging studies done for another indication. However, these cysts can cause pancreatitis or jaundice. These cysts may be found in various locations throughout the gland and are seen with equal frequency in both genders. Great efforts are taken to distinguish branch duct IPMN's from serous and mucinous cystadenomas.

The management of branch duct IPMN's is challenging. The lifetime risk of one of these cysts becoming malignant is not entirely known and is difficult to determine. There is no medication to treat these cysts. Patients and their doctors are forced to choose between surveillance and surgical removal. Factors that contribute to this decision include the patient's age, presence or absence of symptoms, the size of the cyst, and whether or not there is a solid component or mural nodule. While surgical removal of these cysts will prevent the patient from developing pancreatic cancer from that cyst, pancreatic surgery is not without risk. The risk of the surgery must be carefully weighed against the risk of malignancy in making a determination about surgical removal versus surveillance.

Patients with the branch duct variant of IPMN generally can be safely observed if:

  1. The cyst is asymptomatic
  2. The cyst is less than 3 cm
  3. The cyst has no solid component or mural nodule