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Cystic pancreatic lesions identified with increasing frequency as result of widespread use of imaging; researchers provide guidance for their diagnosis, management

Saturday, October 18 2008 | Comments

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What's This? By Courtneay Parsons

In recent years, cystic lesions of the pancreas have been encountered with increasing frequency, at least in part because of the increasingly widespread use of abdominal imaging. As a result, recent research has focused on resolving many unanswered questions regarding the diagnosis and management of pancreatic neoplasms.

Diagnosis and oncologic risk stratification should be accomplished with a patient history, radiographic imaging, and/or invasive testing, noted Dr. C. Max Schmidt with the Walther Oncology Center at Indiana University.

A patient history is an essential part of the diagnostic workup, Dr. Schmidt explained, as patient characteristics (eg, age and sex) and specific symptoms can help shape a diagnosis. Some symptoms, such as pancreatitis and diabetes, may help distinguish between intraductal papillary mucinous neoplasms (IPMNs) and other types of cysts. In addition, certain high-risk symptoms, such as obstructive jaundice, suggest a higher risk of malignancy. At the same time, factors such as age and sex have shown associations with specific types of tumors. For example, serous cystadenomas (SCAs) and solid pseudopapillary neoplasms are associated with female sex, whereas IPMNs and malignancies are more common with increasing age.

Radiographic imaging with computed tomography (CT) or magnetic resonance cholangiopancreatography (MRI-MRCP) should also play a role in the diagnosis and assessment of malignant potential, but the use of positron emission tomography in this process still requires prospective validation, Dr. Schmidt explained. Both CT and MRI-MRCP seem to reliably detect most cysts, he noted. Overall, there doesn't seem to be a benefit of MRI-MRCP over CT, except perhaps for the identification of IPMNs. CT and MRI-MRCP may also be helpful for determining malignant potential if characteristic features are present, such as mural nodules, metastasis, or main pancreatic duct dilation.

Endoscopic ultrasound (EUS) alone does not seem to improve upon results obtained with radiographic imaging, although EUS combined with cyst fluid analysis may help differentiate between mucinous and nonmucinous cysts. 

In addition to these tools, Dr. Schmidt and colleagues have begun to evaluate the potential role of novel cyst fluid markers, such as prostaglandin E2 (PGE2). Although the use of such markers requires validation with prospective studies, research has shown PGE2 levels to be lower in patients with SCAs and mucinous cystic neoplasms (MCNs) relative to those with IPMNs; findings also suggest that PGE2 levels may help identify malignancy.

When approaching the diagnostic workup, Dr. Schmidt advised, physicians should consider fit patients for surgery who have symptoms--especially high-risk symptoms--and/or concerning radiographic features. If a patient is not fit for surgery, he recommended gathering more information with invasive testing (EUS plus fine needle aspiration) to determine whether the risk of surgery outweighs the risk of cancer. In addition, invasive testing may be warranted even in patients without high-risk symptoms or suspicious radiographic findings, as a small percentage of these patients will still have a malignancy.

To help further clarify the role of surgery in the management of pancreatic neoplasms, Dr. Michael Farnell with the Mayo Clinic in Rochester, Minnesota, and Dr. Taylor Riall with the University of Texas Medical Branch in Galveston provided evidence-based recommendations to help physicians decide whether surgery is necessary or observation is appropriate in patients with serous cystic neoplasms (SCNs), MCNs, or IPMNs.

In general, Dr. Farnell noted, candidates for an observational approach include individuals who are asymptomatic, show no evidence of mural nodules in radiographic imaging, and have a cyst size of <3 cm, a main duct size of <6 mm, and negative cytology findings.

With respect to tumor type, Drs. Farnell and Riall noted that SCNs are rarely malignant and can be observed, although surgery may be warranted for larger cysts, if symptoms are present, or if there is diagnostic uncertainty. By contrast, because of their malignant potential, MCNs and main-duct IPMNs should be resected in all fit patients. Branch-duct IPMNs may be observed if none of the International Consensus Guidelines criteria are present, but surgery is warranted otherwise in fit patients.

In the case of MCNs and IPMNs, Dr. Riall emphasized, physicians who take an aggressive surgical approach have a relatively unique opportunity to remove the neoplasm before invasive cancer develops.

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