Accuracy and agreement of a large panel of endosonographers for endomicroscopy-guided virtual biopsy of pancreatic cystic lesions

Interobserver agreement in dysplasia grading of intraductal papillary mucinous neoplasms: performance of Kyoto guidelines and optimization of endomicroscopy biomarkers through pathology reclassification

BACKGROUND AND AIMS

Interobserver agreement (IOA) among pancreaticobiliary (PB) pathologists in evaluating high-grade dysplasia and/or invasive carcinoma (HGD-IC) of intraductal papillary mucinous neoplasms (IPMNs) remains understudied. EUS-guided needle-based confocal endomicroscopy (nCLE) can evaluate papillary architecture in branch duct IPMNs. We assessed IOA among PB pathologists in classifying dysplasia in resected IPMNs and compared the performance of the Kyoto guidelines' high-risk stigmata (HRS) and presurgical EUS-nCLE against reclassified pathology.

METHODS

Participants in prospective clinical trials (2015-2023) with resected IPMNs were included. Blinded PB pathologists independently reviewed histopathology, achieving a consensus diagnosis. The accuracies of cyst fluid next-generation sequencing analysis, EUS-nCLE, and Kyoto HRS in predicting HGD-IC were compared with the reclassified pathology.

RESULTS

Among 64 participants, 25 (39%) exhibited HGD-IC (17 HGD, 8 invasive carcinoma). Disagreements occurred in 14% of cases with substantial IOA (κ = 0.70; 95% confidence interval, 0.53-0.88) between 2 PB pathologists for differentiating HGD-IC versus low-grade dysplasia (LGD). To detect HGD-IC, the sensitivity, specificity, and accuracy of Kyoto HRS and EUS-nCLE were 52%, 95%, 78% and 68%, 87%, 80%, respectively. Integrating nCLE with Kyoto HRS improved sensitivity to 80%, with specificity and accuracy at 82% and 81%, respectively. The sensitivity, specificity, and accuracy of next-generation sequencing (n = 47) to detect HGD-IC were 6.3%, 100%, and 68%, respectively. A unique subset of IPMNs were identified in all (n = 8, P = .01) cases where presurgical EUS-nCLE underestimated dysplasia revealing a distinct micropapillary architecture on postsurgical histopathology.

CONCLUSIONS

Despite substantial IOA among experienced PB pathologists, a second pathologist's review may be warranted for dysplasia classification in IPMNs under certain circumstances. Incorporating an imaging biomarker such as EUS-nCLE with Kyoto HRS improves sensitivity for HGD-IC without sacrificing accuracy.

Role of Endoscopy in Clinical Management of Intraductal Papillary Mucinous Neoplasms

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a well-recognized precursor of pancreatic carcinoma. Along with cross-sectional abdominal imaging tests, endoscopic examinations remain the cornerstone in the diagnosis of pancreatic cysts, early detection of IPMN-derived carcinomas, and risk stratification of patients with IPMNs for subsequent surveillance strategies. In particular, endoscopic ultrasound (EUS) facilitates the optimal patient management by providing high-resolution morphological information, and the contrast-enhanced harmonic mode may further enhance diagnostic accuracy. EUS-guided fine-needle aspiration for solid mass and/or cyst fluid is considered for pathological and molecular examinations for the diagnosis of pancreatic cysts and malignancy. Emerging evidence suggests the usefulness of through-the-needle biopsy and confocal laser microendoscopy in this setting. In addition to the undoubtful diagnostic utility, recent studies have demonstrated the potential effect of endoscopic interventions (i.e., ablation) on the control of IPMNs. Despite the increasing role of endoscopy in the clinical management of IPMNs, there remains a gap in our understanding of how to utilize endoscopy in the personalized care for patients with IPMNs (e.g., the optimal interval of EUS) and the prevention of deaths due to pancreatic carcinomas developing concomitantly with IPMNs. This review summarizes the current evidence on the role of endoscopy in both the diagnostic and therapeutic landscapes of clinical management of IPMNs and identifies key clinical unmet needs that should be addressed in future research. Combined with emerging technologies (e.g., artificial intelligence and high-throughput molecular profiling), endoscopy would offer more effective and tailored management strategies for patients with IPMNs.

Histologic Diagnosis of Pancreatic Cystic Lesions with Endoscopic Ultrasound Fine Needle Biopsy and Impact on Management Decisions

PURPOSE

Endoscopic ultrasound with fine needle biopsy (EUS-FNB) has not been well studied in pancreatic cystic lesions (PCLs). This study evaluates the diagnostic performance of EUS-FNB for PCLs and its impact on management decisions.

METHODS

We conducted a single-center, retrospective study of patients who had EUS-FNB between March 2016 and February 2024. We included patients with ≥ 6-month follow-up and excluded those with a solid pancreatic mass. We obtained clinical, radiologic, endoscopic, surgical, laboratory, and pathology data from chart review. We evaluated: (A) diagnostic yield; (B) predictors of diagnostic FNB; (C) diagnostic accuracy compared to surgical histopathology; (D) appropriateness of management decisions; and (E) adverse events. We compared the appropriateness of management decisions between diagnostic and non-diagnostic FNB.

RESULTS

100 subjects underwent EUS-FNB for PCLs (56% microcystic or with mural nodule). FNB yielded a histologic diagnosis in 60% of sampled lesions. Performing 2 or more needle passes was the only significant predictor of a diagnostic FNB (p = 0.02). Compared to surgical histopathology (n = 21), FNB needles highly accurately diagnosed specific cyst types (IPMN = 85.7%, MCN = 90.5%, SCA = 95.2%, NET = 95.2%, SPN = 100%) and malignant PCLs (accuracy = 81.0%; specificity = 100%; sensitivity = 72.7%). There was a 7.2-fold increase of appropriate management decisions when FNB was diagnostic vs. non-diagnostic (p < 0.001). This was due to improvement in surveillance discontinuation for benign cysts and in appropriate surgical resection for malignant PCLs (p < 0.001). Post-FNB pancreatitis occurred in 4% of patients.

CONCLUSION

EUS-FNB accurately diagnoses different PCL types and their degree of neoplasia, leading to more appropriate management decisions. Future prospective studies are needed to confirm these findings.

Endoscopic ultrasound-guided radiofrequency ablation of pancreatic tumors

PURPOSE OF REVIEW

Surgery is a cornerstone in the management of pancreatic cancer and precancerous pancreatic lesions. However, many patients are not suitable candidates for surgery at the time of diagnosis for various reasons. Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) appears to be a promising treatment option for patients who are ineligible for surgery for management of pancreatic adenocarcinoma (PDAC), and pancreatic neuroendocrine tumors (PNETs), and pancreatic cystic lesions (PCLs).

RECENT FINDINGS

EUS-RFA may serve as an adjunct to chemotherapy or palliative measures for inoperable cases of PDAC. Given its feasibility and efficacy, EUS-RFA has an evolving niche as a minimally invasive and potentially definitive treatment for PNETs and high-risk PCLs such as intraductal papillary mucinous neoplasms (IPMNs). EUS-RFA is a generally well tolerated procedure, with abdominal pain and acute pancreatitis being the most common adverse effects, though the risk can be mitigated through prophylactic measures.

SUMMARY

There is an increasing body of evidence to support the use of EUS-RFA in managing pancreatic lesions, either as definitive, adjunctive, or palliative treatment, depending on lesion type.

Endoscopic ultrasound-guided needle-based confocal laser endomicroscopy for pancreatic cystic lesions: current status and future prospects

Pancreatic cystic lesions (PCLs) have increased in prevalence due to the increased usage and advancements in cross-sectional abdominal imaging. Current diagnostic techniques cannot distinguish between PCLs requiring surgery, close surveillance, or expectant management. This has increased the morbidity and healthcare costs from inappropriately aggressive and conservative management strategies. Endoscopic ultrasound (EUS) needle-based confocal laser endomicroscopy (nCLE) allows for microscopic examination and delineation of the surface epithelium of PCLs. Landmark studies have identified characteristics distinguishing various types of PCLs, confirmed the high diagnostic yield of EUS-nCLE (especially for PCLs with an equivocal diagnosis), and shown that EUS-nCLE helps to change management and reduce healthcare costs. Refining procedure technique and reducing procedure length have improved the safety of EUS-nCLE. The utilization of artificial intelligence and its combination with other EUS-based advanced diagnostic techniques would further improve the results of EUS-based PCL diagnosis. A structured training program and device improvements to allow more complete mapping of the pancreas cyst epithelium will be crucial for the widespread adoption of this promising technology.

Endoscopic Ultrasound-Guided Needle-Based Confocal Endomicroscopy as a Diagnostic Imaging Biomarker for Intraductal Papillary Mucinous Neoplasms

Pancreatic cancer is on track to become the second leading cause of cancer-related deaths by 2030, yet there is a lack of accurate diagnostic tests for early detection. Intraductal papillary mucinous neoplasms (IPMNs) are precursors to pancreatic cancer and are increasingly being detected. Despite the development and refinement of multiple guidelines, diagnosing high-grade dysplasia or cancer in IPMNs using clinical, radiologic, endosonographic, and cyst fluid features still falls short in terms of accuracy, leading to both under- and overtreatment. EUS-guided needle-based confocal laser endomicroscopy (nCLE) is a novel technology that allows real-time optical biopsies of pancreatic cystic lesions. Emerging data has demonstrated that EUS-nCLE can diagnose and risk stratify IPMNs more accurately than conventional diagnostic tools. Implementing EUS-nCLE in clinical practice can potentially improve early diagnosis of pancreatic cancer, reduce unnecessary surgeries of IPMNs with low-grade dysplasia, and advance the field of digital pathomics. In this review, we summarize the current evidence that supports using EUS-nCLE as a diagnostic imaging biomarker for diagnosing IPMNs and for risk stratifying their degree of neoplasia. Moreover, we will present emerging data on the role of adding artificial intelligence (AI) algorithms to nCLE and integrating novel fluid biomarkers into nCLE.

Molecular Pathology of Pancreatic Cystic Lesions with a Focus on Malignant Progression

The malignant progression of pancreatic cystic lesions (PCLs) remains understudied with a knowledge gap, yet its exploration is pivotal for effectively stratifying patient risk and detecting cancer at its earliest stages. Within this review, we delve into the latest discoveries on the molecular level, revealing insights into the IPMN molecular landscape and revised progression model, associated histologic subtypes, and the role of inflammation in the pathogenesis and malignant progression of IPMN. Low-grade PCLs, particularly IPMNs, can develop into high-grade lesions or invasive carcinoma, underscoring the need for long-term surveillance of these lesions if they are not resected. Although KRAS and GNAS remain the primary oncogenic drivers of neoplastic development in IPMNs, additional genes that are important in tumorigenesis have been recently identified by whole exome sequencing. A more complete understanding of the genes involved in the molecular progression of IPMN is critical for effective monitoring to minimize the risk of malignant progression. Complicating these strategies, IPMNs are also frequently multifocal and multiclonal, as demonstrated by comparative molecular analysis. Algorithms for preoperative cyst sampling and improved radiomic techniques are emerging to model this spatial and temporal genetic heterogeneity better. Here, we review the molecular pathology of PCLs, focusing on changes associated with malignant progression. Developing models of molecular risk stratification in PCLs which can complement radiologic and clinical features, facilitate the early detection of pancreatic cancer, and enable the development of more personalized surveillance and management strategies are summarized.

Unraveling the enigma: A comprehensive review of solid pseudopapillary tumor of the pancreas

Solid pseudopapillary tumor of the pancreas (SPTP) is a rare neoplasm predominantly observed in young females. Pathologically, CTNNB1 mutations, β-catenin nuclear accumulation, and subsequent Wnt-signaling pathway activation are the leading molecular features. Accurate preoperative diagnosis often relies on imaging techniques and endoscopic biopsies. Surgical resection remains the mainstay treatment. Risk models, such as the Fudan Prognostic Index, show promise as predictive tools for assessing the prognosis of SPTP. Establishing three types of metachronous liver metastasis can be beneficial in tailoring individualized treatment and follow-up strategies. Despite advancements, challenges persist in understanding its etiology, establishing standardized treatments for unresectable or metastatic diseases, and developing a widely recognized grading system. This comprehensive review aims to elucidate the enigma by consolidating current knowledge on the epidemiology, clinical presentation, pathology, molecular characteristics, diagnostic methods, treatment options, and prognostic factors.

Endoscopic Ultrasound-Guided Ablation of Premalignant Pancreatic Cysts and Pancreatic Cancer

Pancreatic cancer is on the rise and expected to become the second leading cause of cancer-related death by 2030. Up to a one-fifth of pancreatic cancers may arise from mucinous pancreatic cysts, which are frequently present in the general population. Currently, surgical resection is the only curative approach for pancreatic cancer and its cystic precursors. However, only a dismal proportion of patients are eligible for surgery. Therefore, novel treatment approaches to treat pancreatic cancer and precancerous pancreatic cysts are needed. Endoscopic ultrasound (EUS)-guided ablation is an emerging minimally invasive method to treat pancreatic cancer and premalignant pancreatic cysts. Different ablative modalities have been used including alcohol, chemotherapy agents, and radiofrequency ablation. Cumulative data over the past two decades have shown that endoscopic ablation of mucinous pancreatic cysts can lead to cyst resolution in a significant proportion of the treated cysts. Furthermore, novel data are emerging about the ability to endoscopically ablate early and locally advanced pancreatic cancer. In this review, we aim to summarize the available data on the efficacy and safety of the different EUS-ablation modalities for the management of premalignant pancreatic cysts and pancreatic cancer.

Structured training program on confocal laser endomicroscopy for pancreatic cystic lesions: a multicenter prospective study among early-career endosonographers (with video)

BACKGROUND AND AIMS

Data on how to teach endosonographers needle-based confocal laser endomicroscopy (nCLE)-guided histologic diagnosis of pancreatic cystic lesions (PCLs) are limited. Hence, we developed and tested a structured educational program to train early-career endosonographers in nCLE-guided diagnosis of PCLs.

METHODS

Twenty-one early-career nCLE-naïve endosonographers watched a teaching module outlining nCLE criteria for diagnosing PCLs. Participants then reviewed 80 high-yield nCLE videos, recorded diagnoses, and received expert feedback (phase 1). Observers were then randomized to a refresher feedback session or self-learning at 4 weeks. Eight weeks after training, participants independently assessed the same 80 nCLE videos without feedback and provided histologic predictions (phase 2). Diagnostic performance of nCLE to differentiate mucinous versus nonmucinous PCLs and to diagnose specific subtypes were analyzed using histopathology as the criterion standard. Learning curves were determined using cumulative sum analysis.

RESULTS

Accuracy and diagnostic confidence for differentiating mucinous versus nonmucinous PCLs improved as endosonographers progressed through nCLE videos in phase 1 (P < .001). Similar trends were observed with the diagnosis of PCL subtypes. Most participants achieved competency interpreting nCLE, requiring a median of 38 assessments (range, 9-67). During phase 2, participants independently differentiated PCLs with high accuracy (89%), high confidence (83%), and substantial interobserver agreement (κ = .63). Accuracy for nCLE-guided PCL subtype diagnoses ranged from 82% to 96%. The learned nCLE skills did not deteriorate at 8 weeks and were not impacted by a refresher session.

CONCLUSIONS

We developed a practical, effective, and durable educational intervention to train early-career endosonographers in nCLE-guided diagnosis of PCLs.

The Hong Kong consensus recommendations on the diagnosis and management of pancreatic cystic lesions

Background

The finding of pancreatic cystic lesions (PCL) on incidental imaging is becoming increasingly common. International studies report a prevalence of 2.2-44.7% depending on the population, imaging modality and indication for imaging, and the prevalence increases with age. Patients with PCL are at risk of developing pancreatic cancer, a disease with a poor prognosis. This publication summarizes recommendations for the diagnosis and management of PCL and post-operative pancreatic exocrine insufficiency (PEI) from a group of local specialists.

Methods

Clinical evidence was consolidated from narrative reviews and consensus statements formulated during two online meetings in March 2022. The expert panel included gastroenterologists, hepatobiliary surgeons, oncologists, radiologists, and endocrinologists.

Results

Patients with PCL require careful investigation and follow-up due to the risk of malignant transformation of these lesions. They should undergo clinical investigation and pancreas-specific imaging to classify lesions and understand the risk profile of the patient. Where indicated, patients should undergo pancreatectomy to excise PCL. Following pancreatectomy, patients are at risk of PEI, leading to gastrointestinal dysfunction and malnutrition. Therefore, such patients should be monitored for symptoms of PEI, and promptly treated with pancreatic enzyme replacement therapy (PERT). Patients with poor response to PERT may require increases in dose, addition of a proton pump inhibitor, and/or further investigation, including tests for pancreatic function. Patients are also at risk of new-onset diabetes mellitus after pancreatectomy; they should be screened and treated with insulin if indicated.

Conclusions

These statements are an accurate summary of our approach to the diagnosis and management of patients with PCL and will be of assistance to clinicians treating these patients in a similar clinical landscape.

Deep-Learning-Enabled Computer-Aided Diagnosis in the Classification of Pancreatic Cystic Lesions on Confocal Laser Endomicroscopy

Accurate classification of pancreatic cystic lesions (PCLs) is important to facilitate proper treatment and to improve patient outcomes. We utilized the convolutional neural network (CNN) of VGG19 to develop a computer-aided diagnosis (CAD) system in the classification of subtypes of PCLs in endoscopic ultrasound-guided needle-based confocal laser endomicroscopy (nCLE). From a retrospectively collected 22,424 nCLE video frames (50 videos) as the training/validation set and 11,047 nCLE video frames (18 videos) as the test set, we developed and compared the diagnostic performance of three CNNs with distinct methods of designating the region of interest. The diagnostic accuracy for subtypes of PCLs by CNNs with manual, maximal rectangular, and U-Net algorithm-designated ROIs was 100%, 38.9%, and 66.7% on a per-video basis and 88.99%, 73.94%, and 76.12% on a per-frame basis, respectively. Our per-frame analysis suggested differential levels of diagnostic accuracy among the five subtypes of PCLs, where non-mucinous PCLs (serous cystic neoplasm: 93.11%, cystic neuroendocrine tumor: 84.31%, and pseudocyst: 98%) had higher diagnostic accuracy than mucinous PCLs (intraductal papillary mucinous neoplasm: 84.43% and mucinous cystic neoplasm: 86.1%). Our CNN demonstrated superior specificity compared to the state-of-the-art for the classification of mucinous PCLs (IPMN and MCN), with high specificity (94.3% and 92.8%, respectively) but low sensitivity (46% and 45.2%, respectively). This suggests the complimentary role of CNN-enabled CAD systems, especially for clinically suspected mucinous PCLs.

The Role of Genetic, Metabolic, Inflammatory, and Immunologic Mediators in the Progression of Intraductal Papillary Mucinous Neoplasms to Pancreatic Adenocarcinoma

Intraductal papillary mucinous neoplasms (IPMN) have the potential to progress to pancreatic ductal adenocarcinoma (PDAC). As with any progression to malignancy, there are a variety of genetic and metabolic changes, as well as other disruptions to the cellular microenvironment including immune alterations and inflammation, that can contribute to tumorigenesis. Previous studies further characterized these alterations, revealing changes in lipid and glucose metabolism, and signaling pathways that mediate the progression of IPMN to PDAC. With the increased diagnosis of IPMNs and pancreatic cysts on imaging, the opportunity to attenuate risk with the removal of high-risk lesions is possible with the understanding of what factors accelerate malignant progression and how they can be clinically utilized to determine the level of dysplasia and stratify the risk of progression. Here, we reviewed the genetic, metabolic, inflammatory, and immunologic pathways regulating the progression of IPMN to PDAC.

Pancreatic Cystic Neoplasms: Translating Guidelines into Clinical Practice

A combination of several factors, including the increasing use of cross-sectional imaging and an aging population, has led to pancreatic cystic lesions (PCLs) becoming the most detected incidental pancreatic lesions. Accurate diagnosis and risk stratification of PCLs is challenging. In the last decade, several evidence-based guidelines have been published addressing the diagnosis and management of PCLs. However, these guidelines cover different subsets of patients with PCLs and offer varying recommendations regarding diagnostic assessment, surveillance, and surgical resection. Further, recent studies comparing the accuracy of various guidelines have reported significant variations in the rate of missed cancer versus unnecessary surgical resections. In clinical practice, it is challenging to decide which guideline to follow specifically. This article reviews the varying recommendations of the major guidelines and results of comparative studies, provides an overview of newer modalities not included in the guidelines, and offers perspectives on translating the guidelines into clinical practice.

The Role of Magnetic Resonance Imaging (MRI) in the Diagnosis of Pancreatic Cystic Lesions (PCLs)

Pancreatic cystic lesions (PCLs) are a common incidental finding on cross-sectional imaging. Given the high signal to noise and contrast resolution, multi-parametric capability and lack of ionizing radiation, magnetic resonance imaging (MRI) has become the non-invasive method of choice to predict cyst type, risk stratify the presence of neoplasia, and monitor changes during surveillance. In many patients with PCLs, the combination of MRI and the patient's history and demographics will suffice to stratify lesions and guide treatment decisions. In other patients, especially those with worrisome or high-risk features, a multimodal diagnostic approach that includes endoscopic ultrasound (EUS) with fluid analysis, digital pathomics, and/or molecular analysis is often necessary to decide on management options. The application of radiomics and artificial intelligence in MRI may improve the ability to non-invasively stratify PCLs and better guide treatment decisions. This review will summarize the evidence on the evolution of MRI for PCLs, the prevalence of PCLs using MRI, and the MRI features to diagnose specific PCL types and early malignancy. We will also describe topics such as the utility of gadolinium and secretin in MRIs of PCLs, the limitations of MRI for PCLs, and future directions.