What are concerning findings for Intraductal Papillary Mucinous Neoplasm (IPMN)?

From the Guidelines

Intraductal papillary mucinous neoplasms (IPMNs) with concerning findings, such as jaundice, an enhancing mural nodule ≥5 mm, or a main pancreatic duct (MPD) measuring ≥10 mm, should be evaluated for surgical resection, as these features are highly predictive of malignancy 1.

Concerning Features of IPMNs

The following features are associated with an increased risk of high-grade dysplasia or cancer in IPMNs:

• Jaundice
• Enhancing mural nodule ≥5 mm
• MPD dilatation ≥10 mm
• Positive cytology
• Cystic growth-rate ≥5 mm/year
• Increased level of serum CA 19.9 (>37 U/mL)
• Symptoms
• Enhancing mural nodules <5 mm
• Cyst diameter ≥40 mm These features should be evaluated in all patients fit for surgery, as they have a strong association with malignancy 1.

Management of IPMNs

For patients with high-risk features, surgical resection is typically recommended for patients who are suitable surgical candidates. For patients with less concerning features, surveillance with MRI or endoscopic ultrasound every 3-6 months initially, then annually if stable, is appropriate 1. Endoscopic ultrasound with fine needle aspiration may be performed to analyze cyst fluid for CEA levels, amylase, and cytology to better characterize the lesion.

Risk of Malignant Transformation

The risk of malignant transformation in IPMNs varies depending on the type of IPMN. Main duct IPMNs carry a higher risk of malignancy (approximately 40-60%) compared to branch duct IPMNs (15-20%) 1. Early identification of concerning features and appropriate management can prevent progression to pancreatic adenocarcinoma, which has a poor prognosis.

Recent Guidelines

Recent guidelines from the European group and the international group of experts recommend resection in fit patients with main duct IPMNs and certain high-risk features, and surveillance for branch-duct IPMNs without high-risk stigmata 1. The American Gastroenterological Association (AGA) also recommends surgery for patients with both a solid component and a dilated pancreatic duct and/or concerning features on EUS and FNA 1.

From the Research

Findings for IPMN

• The overall accuracy of differentiation between benign and malignant IPMNs using CT and MRI is 86/92% and 83/90%, respectively 2.
• The presence of mural nodules and ductal lesion size ≥30 mm are significant indicators of malignancy (p = 0.02 and p < 0.001, respectively) 2.
• CT and MRI can differentiate benign from malignant forms of IPMN, but identifying (pre)malignant histological IPMN subtypes by CT and MRI is difficult 2.
• The reported incidence of malignancy varies from 57% to 92% in the main duct-IPMN (MD-IPMN) and from 6% to 46% in the branch duct-IPMN (BD-IPMN) 3.
• Features of high-risk malignant lesions include obstructive jaundice, mass lesion of >30 mm, enhanced solid component, and main pancreatic duct (MPD) of size ≥10 mm 3.
• Multidetector-row computed tomography detected a component of invasive carcinoma in IC-IPMC with 86% sensitivity and 100% specificity 4.
• IPMN size (>40 mm), IPMN duct type (main pancreatic duct or mixed type), and the presence of a mural nodule or thick septum are significant predictive factors of malignancy 4.
• EUS-FNA-based cytology has good specificity but poor sensitivity in differentiating benign from malignant IPMNs, with a pooled sensitivity and specificity of 64.8% and 90.6%, respectively 5.
• The Society of Abdominal Radiology (SAR) recommends standardized imaging and reporting for IPMN, including uniform measurement and reporting terminology, to improve patient care and research 6.

Diagnostic Techniques

• CT and MRI are commonly used for diagnosing and differentiating IPMNs 2, 3, 4.
• EUS-FNA is used to diagnose pancreatic cystic lesions, but its diagnostic yield for distinguishing malignant and benign IPMNs is limited 5.
• Multidetector-row computed tomography is useful for detecting invasive carcinoma in IC-IPMC 4.
• Magnetic resonance imaging (MRI) and endoscopic ultrasound (EUS) are primary investigations in diagnosing and following up on IPMN patients 3.

Risk Factors and Prognosis

• The 5-year survival of patients after surgical resection for noninvasive IPMN is reported to be at 77-100%, while for those with invasive carcinoma, it is significantly lower at 27-60% 3.
• The presence of mural nodules, ductal lesion size ≥30 mm, and main pancreatic duct (MPD) of size ≥10 mm are associated with an increased risk of malignancy 2, 3, 4.