Cytology adds value to imaging studies for risk assessment of malignancy in pancreatic mucinous cysts

International consensus guidelines 2012 for the management of IPMN and MCN of the pancreas

The international consensus guidelines for management of intraductal papillary mucinous neoplasm and mucinous cystic neoplasm of the pancreas established in 2006 have increased awareness and improved the management of these entities. During the subsequent 5 years, a considerable amount of information has been added to the literature. Based on a consensus symposium held during the 14th meeting of the International Association of Pancreatology in Fukuoka, Japan, in 2010, the working group has generated new guidelines. Since the levels of evidence for all items addressed in these guidelines are low, being 4 or 5, we still have to designate them "consensus", rather than "evidence-based", guidelines. To simplify the entire guidelines, we have adopted a statement format that differs from the 2006 guidelines, although the headings are similar to the previous guidelines, i.e., classification, investigation, indications for and methods of resection and other treatments, histological aspects, and methods of follow-up. The present guidelines include recent information and recommendations based on our current understanding, and highlight issues that remain controversial and areas where further research is required.

Cytological analysis of small branch-duct intraductal papillary mucinous neoplasms provides a more accurate risk assessment of malignancy than symptoms

OBJECTIVES

The Sendai guidelines for management of patients with clinically suspected intraductal papillary mucinous neoplasms (IPMN) recommend resection of cysts > 30 mm, a dilated main pancreatic duct (MPD) > 6 mm, a mural nodule (MN), symptoms or positive cytology. Although sensitive, asymptomatic cysts, nonspecific symptoms, and a high threshold for positive cytology limit the specificity of the guidelines. We have assessed the value of cytology relative to symptom for predicting malignancy in IPMNs without high-risk imaging features.

MATERIALS AND METHODS

We retrospectively reviewed the clinical, radiological, and cytological data of 31 small branch-duct IPMNs without a MN. The cytological presence of high-grade atypical epithelial cells (HGA) was considered true positive, with a corresponding histology of high-grade dysplasia or invasive carcinoma. The performance of cytology versus symptoms was evaluated by calculating the sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and accuracy.

RESULTS

The sensitivity (0.80), specificity (0.85), and accuracy (0.84) of HGA were higher than the corresponding performance characteristics of symptoms (0.60, 0.45, and 0.48, respectively). The NPV of no HGA on cytology was > 95%.

CONCLUSIONS

Cytology is a better predictor of malignancy than symptoms, for the conservative management of small branch-duct IPMNs. Cytology contributes to a highly accurate triple negative test for malignancy in small IPMN: No dilated MPD, MN or HGA.