Effectiveness of contrast-enhanced endoscopic ultrasound for detecting mural nodules in intraductal papillary mucinous neoplasm of the pancreas and for making therapeutic decisions.

BACKGROUND AND

objectivesThere have been few studies to date evaluating the effectiveness of contrast-enhanced endoscopic ultrasound (CE-EUS) for detecting mural nodules in patients with branch duct-type intraductal papillary mucinous neoplasm (BD-IPMN) of the pancreas. We aim to evaluate the effectiveness of CE-EUS for detecting mural nodules in BD-IPMN. PATIENTS AND

methodsOf the 427 BD-IPMN patients, 21 patients (4.9%) in whom the presence of mural nodules was suggested by CE computed tomography (CT) or magnetic resonance imaging (MRI), or in whom the presence of nodule-like lesions as shown by fundamental EUS, were examined by CE-EUS.

resultsThe mean diameter of cystic lesions was 29.8 ± 12.8 mm. The mean diameter of mural nodules was 9.5 ± 5.7 mm. BD-IPMN was detected in the pancreatic head in 16 cases, pancreatic body in 2 cases, and pancreatic tail in 3 cases. The mean follow-up period was 17.2 ± 11.9 months. The detection rates of mural nodule-like lesions in BD-IPMN patients on CT, MRI, and fundamental EUS were 36.8%, 63.2%, and 100%, respectively. The detection rates of true mural nodules in BD-IPMN patients on CT, MRI, and fundamental EUS were 85.7%, 71.4%, and 100%, respectively. The echo levels of mural nodule-like lesions on fundamental EUS were hyperechoic in 6 patients, isoechoic in 9 patients, and hypoechoic in 6 patients. The final diagnosis was mucus lumps in 14 patients and mural nodules in 7 patients. The contrast patterns observed were avascular, isovascular, and hypervascular in 14, 3, and 4 patients, respectively. No patients showed a hypovascular pattern. Fourteen patients showing an avascular pattern were diagnosed as having mucus lumps, and they were able to avoid surgical resection. Of the 7 patients who were diagnosed as having mural nodules, 5 underwent surgical resection. The pathological findings were adenocarcinoma in 2 patients and adenoma in 3 patients. Of the 3 adenoma patients, fundamental EUS demonstrated a hypoechoic area in 1 patient and an isoechoic area in 2 patients. Of the 2 adenocarcinoma patients, 1 each showed a hypoechoic area and a hyperechoic area. It was difficult to distinguish between patients with adenoma and patients with adenocarcinoma using the echo levels obtained from fundamental EUS.

conclusionsCE-EUS may be useful for avoiding the overdiagnosis of BD-IPMN with mural nodule-like lesions. However, it has difficulty in distinguishing between clearly benign and malignant lesions in BD-IPMN.