Systematic review of challenging issues in pathology of intraductal papillary mucinous neoplasms

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.

Spatial Transcriptomics of Intraductal Papillary Mucinous Neoplasms Reveals Divergent Indolent and Malignant States

PURPOSE

Intraductal papillary mucinous neoplasms (IPMN) occur in 5% to 10% of the population, but only a small minority progress to pancreatic ductal adenocarcinoma (PDAC). The lack of accurate predictors of high-risk disease leads to both unnecessary operations for indolent neoplasms and missed diagnoses of PDAC. Digital spatial RNA profiling (DSP-RNA) provides an opportunity to define and associate transcriptomic states with cancer risk.

EXPERIMENTAL DESIGN

We performed whole-transcriptome DSP-RNA profiling on 10 IPMN specimens encompassing the spectrum of dysplastic changes from normal duct to cancer. Epithelial regions within each tissue were annotated as normal duct, low-grade dysplasia, high-grade dysplasia, or invasive carcinoma. The resulting digital gene expression data were analyzed with R/Bioconductor.

RESULTS

Our analysis uncovered three distinct epithelial transcriptomic states-"normal-like" (cNL), "low risk" (cLR), and "high risk" (cHR)-which were significantly associated with pathologic grade. Furthermore, the three states were significantly correlated with the exocrine, classical, and basal-like molecular subtypes described in PDAC. Specifically, exocrine function diminished in cHR, classical activation distinguished neoplasia (cLR and cHR) from cNL, and basal-like genes were specifically upregulated in cHR. Intriguingly, markers of cHR were detected in normal duct and low-grade dysplasia regions from specimens with PDAC but not from specimens containing only low-grade IPMN.

CONCLUSIONS

DSP-RNA of IPMN revealed low-risk (indolent) and high-risk (malignant) expression programs that correlated with the activity of exocrine and basal-like PDAC signatures, respectively, and distinguished pathologically low-grade specimens from malignant specimens. These findings contextualize IPMN pathogenesis and have the potential to improve risk stratification.

Frozen section pathology in IPMN: A systematic review

Intraductal papillary mucinous neoplasms (IPMNs) resection margins are assessed intraoperatively using frozen section (IFS) pathology. We conducted a systematic review to evaluate the concordance of IFS with permanent histopathology and the association between IFS margin status and recurrence. A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We queried PubMed, Embase, Scopus, and Google Scholar for studies reporting IFS in patients undergoing resection for IPMN. Data, including IFS margin status, recurrence rates, and final pathology, were extracted. Positive margins were defined as high-grade dysplasia or invasive cancer. Seven studies, with a total of 706 patients, met the inclusion criteria. Positive IFS margins were reported in 9.4% of cases, with a high correlation (98%) between IFS and final pathology. Recurrence occurred in 15.4% of patients. Fifty-nine of 85 (69.4%) patients with recurrence of IPMN or intraductal papillary mucinous carcinoma (IPMC) had negative IFS margins. IFS accurately predicts final pathology and is a valuable tool for guiding intraoperative decision-making. A sizeable number of patients experienced recurrence despite negative margins, highlighting the need for adjunct diagnostic modalities and continued surveillance following resection, regardless of margin status.

Spatial analysis of IPMNs defines a paradoxical KRT17-positive, low-grade epithelial population harboring malignant features

Background & Aims

Intraductal papillary mucinous neoplasms (IPMNs) are pancreatic cysts that represent one of the few radiologically identifiable precursors to pancreatic ductal adenocarcinoma (PDAC).Though the IPMN-bearing patient population represents a unique opportunity for early detection and interception, current guidelines provide insufficient accuracy in determining which patients should undergo resection versus surveillance, resulting in a sizable fraction of resected IPMNs only harboring low-grade dysplasia, suggesting that there may be overtreatment of this clinical entity.

Methods

To investigate the transcriptional changes that occur during IPMN progression, we performed spatial transcriptomics using the Nanostring GeoMx on patient samples containing the entire spectrum of IPMN disease including low-grade dysplasia, high-grade dysplasia, and IPMN-derived carcinoma. Single cell RNA sequencing was performed on side branch and main duct IPMN biospecimens.

Results

We identified a subpopulation of histologically low-grade IPMN epithelial cells that express malignant transcriptional features including KRT17 , S100A10 and CEACAM5 , markers that are enriched in PDAC. We validated and refined this high-risk gene signature by integrating our ST analysis with an external ST dataset containing a larger number of IPMN samples including non-tumor bearing IPMN (i.e. low-grade IPMN in isolation). We confirmed the presence of the KRT17+ population using immunofluorescence on a large cohort of patient tissues, revealing a widespread but patchy distribution of KRT17+ cells in histologically low-grade IPMN.

Conclusions

Our study demonstrates that KRT17 marks a distinct transcriptional signature in a subpopulation of epithelial cells within histologically low-grade IPMN. This population of cells likely represents a transitional state of histologically low-grade epithelial cells undergoing progression to a higher grade of dysplasia and thus may represent a higher risk of progression to carcinoma.

Graphical abstract

Diagnostic Pearls and Pitfalls in the Evaluation of Biopsies of the Pancreas

CONTEXT.—

The examination of small pancreatic biopsies is a difficult task for pathologists. This is due to the scant and fragmented material often obtained from diagnostic procedures as well as the significant overlap between different neoplastic and nonneoplastic entities. In the upcoming neoadjuvant era, biopsies could become even more important, representing the only possibility to look at the real histomorphology of tumors before chemotherapy-induced modifications.

OBJECTIVES.—

To summarize and discuss the state-of-the-art diagnostic workflow for small pancreatic biopsies, including the most important morphologic and immunohistochemical features and molecular alterations. The main diagnostic pearls and pitfalls of this challenging scenario are also discussed. The most important topics of this review are represented by: (1) pancreatic ductal adenocarcinoma, along with its main differential diagnoses, including autoimmune pancreatitis; (2) solid hypercellular neoplasms, including neuroendocrine neoplasms, acinar cell carcinoma, pancreatoblastoma, and solid pseudopapillary neoplasms; and (3) cystic lesions. Real-world considerations will also be presented and discussed.

DATA SOURCES.—

Sources included a literature review of published studies and the author's own work.

CONCLUSIONS.—

The correct diagnosis of pancreatic lesions is a crucial step in the therapeutic journey of patients. It should be based on robust, standardized, and reliable hallmarks. As presented and discussed here, the integration of morphology with immunohistochemistry, and, in selected cases, with molecular analysis, represents a decisive step in this complex scenario.

Extrahepatic Biliary Mucinous Cystic Neoplasm as an Uncommon Cause of Acute Cholangitis

Biliary mucinous cystic neoplasms (BMCNs) are rare tumors that account for less than 5% of cystic lesions in the biliary tract, predominantly affecting middle-aged women and often presenting as asymptomatic or with nonspecific symptoms. The primary treatment is surgical resection with negative margins. We report a case of grade I non-invasive BMCN that was completely extrahepatic, treated with biliary resection and hepaticojejunostomy. A 42-year-old female with a history of type 2 diabetes was referred for multiple episodes of acute cholangitis. Magnetic resonance cholangiography revealed complete occupation of the common bile duct by a multilocular lesion with thin septa extending into the left main bile duct. Biliary resection with Roux-en-Y hepaticojejunostomy was performed. Histopathological examination identified a mucinous cystic neoplasm with no evidence of cellular atypia, invasion, or malignancy. BMCNs are characterized by multilocular cysts lined by mucin-producing epithelium and a subepithelial stroma resembling ovarian tissue, suggesting hormonal dependence and an embryological origin. Preoperative diagnosis relies on imaging studies, with computed tomography being crucial for identifying the distinctive "cyst-in-cyst" appearance with septa. Complete resection is the preferred treatment due to the risk of malignancy, though recurrence remains a challenge in invasive cases. Mucinous cystic neoplasms of the liver are rare lesions, especially those that are extrahepatic, presenting diagnostic and therapeutic challenges. Continued research into this pathology is essential to optimize its management, treatment, and prognosis, particularly in cases of recurrence.

Multi-omic markers of intraductal papillary mucinous neoplasms progression into pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal and common form of pancreatic cancer, it has no specific symptoms, and most of the patients are diagnosed when the disease is already at an advanced stage. Chemotherapy typically has only a modest effect, making surgery the most effective treatment option. However, only a small percentage of patients are amenable to surgery. One viable strategy to reduce PDAC death burden associated with the disease is to focus on precursor lesions and identify markers able to predict who will evolve into PDAC. While most PDACs are believed to be preceded by pancreatic intraepithelial neoplasms (PanINs), 5-10 % arise from Intraductal papillary mucinous neoplasms (IPMNs), which are mass-forming cystic lesions that are very common in the general population. IPMNs offer an invaluable model of pancreatic carcinogenesis for researchers to analyse, as well as a target population for PDAC early detection by clinicians. The evolution of IPMN into cancer is a complex and multistep process, therefore the identification of individual markers will not be the solution. In recent years, multiple omics technologies have been instrumental to identify possible biomarkers of IPMN progression and carcinogenesis. The only foreseeable strategy will be to integrate multi-omics data, alongside clinical and morphological features, into a progression score or signature using either standard epidemiologic tools or artificial intelligence. The aim of this manuscript is to review the current knowledge on genetic biomarkers and to briefly mention also additional omics, such as metabolomics, the exposome, the miRNome and epigenomics of IPMNs.

Unraveling the Long-term Natural History of Branch Duct Intraductal Papillary Mucinous Neoplasm: Beyond 10 years

OBJECTIVE

To describe the long-term natural history of branch duct intraductal papillary mucinous neoplasm (BD-IPMN).

BACKGROUND

The BD-IPMN is a known precursor of pancreatic cancer, yet its long-term natural history is largely unknown.

METHODS

We retrospectively reviewed patients with BD-IPMN who were followed at the Massachusetts General Hospital for at least 10 years without surgical intervention. Patient and cyst characteristics, development of worrisome features (WF), need for surgery, and malignancy were recorded. The risk of pancreatic cancer in this cohort was compared with the general population by determining the standardized incidence ratio.

RESULTS

Three hundred sixteen patients with BD-IPMN who were followed for at least 10 years without intervention were identified. The median age was 63 years, and the median follow-up was 13.5 years (range: 10-28.8 years). Median cyst size at diagnosis was 1.2 cm (IQR: 0.8-1.7), was 1.8 cm (IQR: 1.2-2.6) at 10 years, and increased to 2.0 cm (IQR: 1.3-3.0) by the end of surveillance. At the 10-year mark, 24% of patients had WF, and by the end of surveillance, an additional 20% had developed WF or high-risk stigmata. 8.2% of patients developed pancreatic malignancy (high-grade dysplasia or invasive cancer). The standardized incidence ratio for pancreatic cancer was 9.28 (95% CI: 5.82-14.06), with almost two-thirds of invasive cancers occurring within the pancreatic cyst.

CONCLUSIONS

After 10 years of surveillance for BD-IPMN without intervention, the disease continues to progress, and 1 of every 12 patients will develop malignancy. The risk of pancreatic cancer appears to be 9 times higher than in the comparable age-matched population.

An Overview for Clinicians on Intraductal Papillary Mucinous Neoplasms (IPMNs) of the Pancreas

Currently, there is no reliable method of discerning between low-risk and high-risk intraductal papillary mucinous neoplasms (IPMNs). Operative resection is utilized in an effort to resect those lesions with high-grade dysplasia (HGD) prior to the development of invasive disease. The current guidelines recommend resection for IPMN that involve the main pancreatic duct. Resecting lesions with HGD before their progression to invasive disease and the avoidance of resection in those patients with low-grade dysplasia is the optimal clinical scenario. Therefore, the importance of developing preoperative models able to discern HGD in IPMN patients cannot be overstated. Low-risk patients should be managed with nonsurgical treatment options (typically MRI surveillance), while high-risk patients would undergo resection, hopefully prior to the formation of invasive disease. Current research is evolving in multiple directions. First, there is an ongoing effort to identify reliable markers for predicting malignant transformation of IPMN, mainly focusing on genomic and transcriptomic data from blood, tissue, and cystic fluid. Also, multimodal models of combining biomarkers with clinical and radiographic data seem promising for providing robust and accurate answers of risk levels for IPMN patients.

Spatial Transcriptomics of IPMN Reveals Divergent Indolent and Malignant Lineages

Purpose

Intraductal papillary mucinous neoplasms (IPMN) occur in 5-10% of the population, but only a small minority progress to pancreatic ductal adenocarcinoma (PDAC). The lack of accurate predictors of high-risk disease leads both to unnecessary operations for indolent neoplasms as well as missed diagnoses of PDAC. Digital spatial RNA profiling (DSP-RNA) provides an opportunity to define and associate transcriptomic states with cancer risk.

Experimental Design

Whole-transcriptome DSP-RNA profiling was performed on 10 IPMN specimens encompassing the spectrum of dysplastic changes from normal duct to cancer. Ductal epithelial regions within each tissue were annotated as normal duct (NL), low-grade dysplasia (LGD), high-grade dysplasia (HGD), or invasive carcinoma (INV). Gene expression count data was generated by Illumina sequencing and analyzed with R/Bioconductor.

Results

Dimension reduction analysis exposed three clusters reflecting IPMN transcriptomic states denoted "normal-like" ( cNL ), "low-risk" ( cLR ) and "high-risk" ( cHR ). In addition to specific marker genes, the three states exhibited significant enrichment for the exocrine, classical, and basal-like programs in PDAC. Specifically, exocrine function diminished in cHR , classical activation distinguished neoplasia from cNL , and basal-like genes were specifically upregulated in cHR . Intriguingly, markers of cHR were detected in NL and LGD regions from specimens with PDAC but not low-grade IPMN.

Conclusions

DSP-RNA of IPMN revealed low-risk (indolent) and high-risk (malignant) expression programs that correlated with the activity of exocrine and basal-like PDAC signatures, respectively, and distinguished pathologically low-grade from malignant specimens. These findings contextualize IPMN pathogenesis and have the potential to transform existing risk stratification models.

Statement of translational relevance

Current consensus guidelines for management of intraductal papillary mucinous neoplasms (IPMN) of the pancreas utilize clinical and radiographic criteria for risk stratification. Unfortunately, the estimated positive predictive value of these criteria for IPMN-associated pancreatic ductal adenocarcinoma (PDAC) is under 50%, indicating that over half of pancreatectomies are performed for benign disease. Moreover, nearly 15% of patients who were deemed "low risk" by the same criteria harbored PDAC. Surgical resection of IPMN has maximal benefit when performed prior to the development of PDAC, as evidence of carcinoma has been associated with a high rate of recurrence and poor overall survival. Thus, the development of molecular diagnostics that improve the accuracy of IPMN risk classification would have immediate relevance for patient care, both in terms of better selecting patients for potentially curative operations, as well as sparing patients with low-risk lesions from invasive procedures.

Prospective multicenter surveillance study of branch-duct intraductal papillary mucinous neoplasm of the pancreas; risk of dual carcinogenesis

BACKGROUND

The natural history of branch-duct intraductal papillary mucinous cystic neoplasms (BD-IPMNs) in the pancreas remains unclear. This study aimed to answer this clinical question by focusing on the development of concomitant pancreatic ductal adenocarcinomas (cPDAC).

METHODS

The Japan Pancreas Society conducted a prospective multicenter surveillance study of BD-IPMN every six months for five years. The primary endpoints were progression of BD-IPMN, progression to high-grade dysplasia/invasive carcinoma (HGD/IC), and cPDAC. Factors predicting the progression of BD-IPMN to HGD/IC and development of cPDAC were also assessed as secondary endpoints.

RESULTS

Among the 2104 non-operated patients, 348 (16.5 %) showed progression of primary BD-IPMN. Cumulative incidences of BD-IPMN with HGD/IC and cPDAC during the 5.17-year surveillance period were 1.90 % and 2.11 %, respectively, and standard incidence ratios of BD-IPMN with HGD/IC and cPDAC were 5.28 and 5.73, respectively. Of 38 cPDACs diagnosed during surveillance, 25 (65.8 %) were resectable. The significant predictive characteristics of BD-IPMN for progression to HGD/IC were larger cyst size (p = 0.03), larger main pancreatic duct size (p < 0.01), and mural nodules (p = 0.02). Significant predictive characteristics for the development of cPDAC were male sex (p = 0.03) and older age (p = 0.02), while the size of IPMN was not significant.

CONCLUSION

Careful attention should be given to "dual carcinogenesis" during BD-IPMN surveillance, indicating the progression of BD-IPMN to HGD/IC and development of cPDAC distinct from BD-IPMN, although the establishment of risk factors that predict cPDAC development remains a challenge (UMIN000007349).

An international multi-institutional validation of T1 sub-staging of intraductal papillary mucinous neoplasm-derived pancreatic cancer

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN)-derived pancreatic ductal adenocarcinoma (PDAC) is resected at smaller sizes compared with its biologically distinct counterpart, pancreatic intraepithelial neoplasia (PanIN)-derived PDAC. Thus, experts proposed T1 sub-staging for IPMN-derived PDAC. However, this has never been validated.

METHODS

Consecutive upfront surgery patients with IPMN-derived PDAC from 5 international high-volume centers were classified by the proposed T1 sub-staging classification (T1a ≤0.5, T1b >0.5 and ≤1.0, and T1c >1.0 and ≤2.0 cm) using the invasive component size. Kaplan-Meier and log-rank tests were used to compare overall survival (OS). A multivariable Cox regression was used to determine hazard ratios (HRs) with confidence intervals (95% CIs).

RESULTS

Among 747 patients, 69 (9.2%), 50 (6.7%), 99 (13.0%), and 531 patients (71.1%), comprised the T1a, T1b, T1c, and T2-4 subgroups, respectively. Increasing T-stage was associated with elevated CA19-9, poorer grade, nodal positivity, R1 margin, and tubular subtype. Median OS for T1a, T1b, T1c, and T2-4 were 159.0 (95% CI = 126.0 to NR), 128.8 (98.3 to NR), 77.6 (48.3 to 108.2), and 31.4 (27.5 to 37.7) months, respectively (P < .001). OS decreased with increasing T-stage for all pairwise comparisons (all P < .05). After risk adjustment, older than age 65, elevated CA19-9, T1b [HR = 2.55 (1.22 to 5.32)], T1c [HR = 3.04 (1.60 to 5.76)], and T2-4 [HR = 3.41 (1.89 to 6.17)] compared with T1a, nodal positivity, R1 margin, and no adjuvant chemotherapy were associated with worse OS. Disease recurrence was more common in T2-4 tumors (56.4%) compared with T1a (18.2%), T1b (23.9%), and T1c (36.1%, P < .001).

CONCLUSION

T1 sub-staging of IPMN-derived PDAC is valid and has significant prognostic value. Advancing T1 sub-stage is associated with worse histopathology, survival, and recurrence. T1 sub-staging is recommended for future guidelines.

Histological variants of pancreatic ductal adenocarcinoma: a survival analysis

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) can be classified into distinct histological subtypes based on the WHO nomenclature. The aim of this study was to compare the prognosis of conventional PDAC (cPDAC) against the other histological variants at the population level.

METHODS

The Surveillance, Epidemiology and End Results (SEER) database was used to identify patients with microscopically confirmed PDAC. These patients were divided into 9 histological subgroups. Overall survival was assessed using the Kaplan-Meier method and Cox regression models stratified by tumor histology.

RESULTS

A total of 159,548 patients with PDAC were identified, of whom 95.9% had cPDAC, followed by colloid carcinoma (CC) (2.6%), adenosquamous carcinoma (ASqC) (0.8%), signet ring cell carcinoma (SRCC) (0.5%), undifferentiated carcinoma (UC) (0.1%), undifferentiated carcinoma with osteoclast-like giant cells (UCOGC) (0.1%), hepatoid carcinoma (HC) (0.01%), medullary carcinoma of the pancreas (MCP) (0.006%) and pancreatic undifferentiated carcinoma with rhabdoid phenotype (PUCR) (0.003%). Kaplan-Meier curves showed that PUCR had the worst prognosis (median survival: 2 months; 5-year survival: 0%), while MCP had the best prognosis (median survival: 41 months; 5-year survival: 33.3%). In a multivariable Cox model, several histological subtypes (i.e. CC, ASqC, SRCC, UCOGC) were identified as independent predictors of overall survival when compared to cPDAC.

CONCLUSION

PDAC is a heterogenous disease and accurate identification of variant histology is important for risk stratification, as these variants may have different biological behavior.

Consequences of a Surveillance Strategy for Side-branch Intraductal Pancreatic Mucinous Neoplasms: Long-term Follow-up of One Thousand Cysts

OBJECTIVE

To quantify the rate of progression in surveilled cysts and assess what factors should indicate delayed resection.

BACKGROUND

Side-branch intraductal papillary mucinous neoplasms (SB-IPMNs) are increasingly discovered, making it challenging to identify which patients require resection, thus avoiding inappropriate treatment. Most incidental lesions are surveyed, yet the consequences of that decision remain uncertain.

METHODS

A prospectively maintained database of pancreatic cystic neoplasms was queried for patients with SB-IPMN. Patients with ≥2 imaging studies >6 months apart were included. Clinically relevant progression (CR-progression) was defined by symptoms, worrisome/high-risk stigmata, or invasive cancer (IC). Growth ≥5 mm in 2 years is considered CR-progression; size ≥3 cm alone is not.

RESULTS

Between 1997 and 2023, 1337 patients were diagnosed with SB-IPMN. Thirty-seven (2.7%) underwent up-front surgery; 1000 (75.0%) had >6 months of surveillance.The rate of CR-progression was 15.3% (n = 153) based on size increase (n = 63, 6.3%), main-duct involvement (n = 48, 4.8%), symptoms (n = 8, 5.0%), or other criteria (n = 34, 3.4%). At a median follow-up of 6.6 years (interquartile range: 3.0-10.26), 17 patients (1.7%) developed IC. Those with CR-progression developed IC in 11.1% (n = 17) and high-grade dysplasia (HGD) in 6.5% (n = 10). Nearly half of the cancers were not contiguous with the surveyed SB-IPMN.Size ≥3 cm was not associated with HGD/IC ( P = 0.232). HGD/IC was least common in CR-progression determined by size growth (6.3%) versus main-duct involvement (24%) or other (43%, P < 0.001)Patients with CR-progression demonstrated improved survival (overall survival) with resection on time-to-event ( P < 0.001) and multivariate Cox regression (hazard ratio = 0.205, 0.096-0.439, P < 0.001) analyses. Overall survival was not improved with resection in all patients ( P = 0.244).

CONCLUSIONS

CR-progression for SB-IPMNs is uncommon, with the development of cancer anywhere in the pancreas being rare. Initial size should not drive resection. Long-term and consistent nonoperative surveillance is warranted, with surgery currently reserved for CR-progression, knowing that the majority of these still harbor low-grade pathology.

A Review of the Indications, Outcomes, and Postoperative Management After Total and Completion Pancreatectomy for Pancreatic Cancer: More Is Not Necessarily Better

With improvements in surgical technique and advances in pancreatic endocrine and exocrine replacement therapy, the indications for, and threshold to perform, total or completion pancreatectomy in the modern surgical era are ever evolving. The following review will evaluate such indications for pancreatic cancer including pancreatic ductal adenocarcinoma and intraductal papillary mucinous neoplasms. The authors also review the literature on oncologic outcomes of total and completion pancreatectomy for pancreatic cancer. Finally, they discuss the quality of life and postoperative management of the a-pancreatic state.

Diagnostics and Management of Pancreatic Cystic Lesions-New Techniques and Guidelines

Pancreatic cystic lesions (PCLs) are increasingly diagnosed owing to the wide use of cross-sectional imaging techniques. Accurate identification of PCL categories is critical for determining the indications for surgical intervention or surveillance. The classification and management of PCLs rely on a comprehensive and interdisciplinary evaluation, integrating clinical data, imaging findings, and cyst fluid markers. EUS (endoscopic ultrasound) has become the widely used diagnostic tool for the differentiation of pancreatic cystic lesions, offering detailed evaluation of even small pancreatic lesions with high sensitivity and specificity. Additionally, endoscopic ultrasound-fine-needle aspiration enhances diagnostic capabilities through cytological analysis and the assessment of fluid viscosity, tumor glycoprotein concentration, amylase levels, and molecular scrutiny. These detailed insights play a pivotal role in improving the clinical prognosis and management of pancreatic neoplasms. This review will focus mainly on the latest recommendations for the differentiation, management, and treatment of pancreatic cystic lesions, highlighting their clinical significance.

Comprehensive analysis of clinical data and radiomic features from contrast enhanced CT for differentiating benign and malignant pancreatic intraductal papillary mucinous neoplasms

The primary aim of this investigation was to leverage radiomics features derived from contrast-enhanced abdominal computed tomography (CT) scans to devise a predictive model to discern the benign and malignant nature of intraductal papillary mucinous neoplasms (IPMNs). Radiomic signatures were meticulously crafted to delineate benign from malignant IPMNs by extracting pertinent features from contrast-enhanced CT images within a designated training cohort (n = 84). Subsequent validation was conducted with data from an independent test cohort (n = 37). The discriminative ability of the model was quantitatively evaluated through receiver operating characteristic (ROC) curve analysis, with the integration of carefully selected clinical features to improve the comparative analysis. Arterial-phase images were utilized to construct a model comprising 8 features for distinguishing between benign and malignant cases. The model achieved an accuracy of 0.891 [95% confidence interval (95% CI), 0.816-0.996] in the cross-validation set and 0.553 (95% CI 0.360-0.745) in the test set. Conversely, employing 9 features from the venous-phase resulted in a model with a cross-validation accuracy of 0.862 (95%CI 0.777-0.946) and a test set accuracy of 0.801 (95% CI 0.653-0.950).Integrating the identified clinical features with imaging features yielded a model with a cross-validation accuracy of 0.934 (95% CI 0.879-0.990) and a test set accuracy of 0.904 (95% CI 0.808-0.999), thereby further improving its discriminatory ability. Our findings distinctly illustrate that venous-phase radiomics features eclipse arterial-phase radiomic features in terms of predictive accuracy regarding the nature of IPMNs. Furthermore, the synthesis and meticulous screening of clinical features with radiomic data significantly increased the diagnostic efficacy of our model, underscoring the pivotal importance of a comprehensive and integrated approach for accurate risk stratification in IPMN management.

A narrative review on rare types of pancreatic cancer: should they be treated as pancreatic ductal adenocarcinomas?

Pancreatic cancer is one of the deadliest malignancies in humans and it is expected to play a bigger part in cancer burden in the years to come. Pancreatic ductal adenocarcinoma (PDAC) represents 85% of all primary pancreatic malignancies. Recently, much attention has been given to PDAC, with significant advances in the understanding of the mechanisms underpinning disease initiation and progression, along with noticeable improvements in overall survival in both localized and metastatic settings. However, given their rarity, rare histological subtypes of pancreatic cancer have been underappreciated and are frequently treated as PDAC, even though they might present non-overlapping molecular alterations and clinical behavior. While some of these rare histological subtypes are true variants of PDAC that should be treated likewise, others represent separate clinicopathological entities, warranting a different therapeutic approach. In this review, we highlight clinical, pathological, and molecular aspects of rare histological types of pancreatic cancer, along with the currently available data to guide treatment decisions.

Multi-omic profiling of intraductal papillary neoplasms of the pancreas reveals distinct expression patterns and potential markers of progression

In order to advance our understanding of precancers in the pancreas, 69 pancreatic intraductal papillary neoplasms (IPNs), including 64 intraductal papillary mucinous neoplasms (IPMNs) and 5 intraductal oncocytic papillary neoplasms (IOPNs), 32 pancreatic cyst fluid samples, 104 invasive pancreatic ductal adenocarcinomas (PDACs), 43 normal adjacent tissues (NATs), and 76 macro-dissected normal pancreatic ducts (NDs) were analyzed by mass spectrometry. A total of 10,246 proteins and 22,284 glycopeptides were identified in all tissue samples, and 756 proteins with more than 1.5-fold increase in abundance in IPMNs relative to NDs were identified, 45% of which were also identified in cyst fluids. The over-expression of selected proteins was validated by immunolabeling. Proteins and glycoproteins overexpressed in IPMNs included those involved in glycan biosynthesis and the immune system. In addition, multiomics clustering identified two subtypes of IPMNs. This study provides a foundation for understanding tumor progression and targets for earlier detection and therapies.

Significance

This multilevel characterization of intraductal papillary neoplasms of the pancreas provides a foundation for understanding the changes in protein and glycoprotein expression during the progression from normal duct to intraductal papillary neoplasm, and to invasive pancreatic carcinoma, providing a foundation for informed approaches to earlier detection and treatment.

Fusion genes in pancreatic tumors

Gene fusions and rearrangements play a crucial role in tumor biology. They are rare events typically detected in KRAS wild-type (WT) pancreatic tumors. Their identification can inform clinical management by enabling precision oncology, as fusions involving BRAF, FGFR2, RET, NTRK, NRG1, and ALK represent actionable targets in KRAS-WT cancers, and serve diagnostic purposes since fusions involving PRKACA/B represent the diagnostic hallmark of intraductal oncocytic papillary neoplasms (IOPNs). Although they are rare, the therapeutic and diagnostic importance of these genomic events should not be underestimated, highlighting the need for quality-ensured molecular diagnostics in the management of cancer. Herein we review the existing literature on the role of fusion genes in pancreatic tumors and their clinical potential as effective biomarkers and therapeutic targets.

A Comparison of Spatial and Phenotypic Immune Profiles of Pancreatic Ductal Adenocarcinoma and Its Precursor Lesions

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a 5-year survival rate of 12.5%. PDAC predominantly arises from non-cystic pancreatic intraepithelial neoplasia (PanIN) and cystic intraductal papillary mucinous neoplasm (IPMN). We used multiplex immunofluorescence and computational imaging technology to characterize, map, and compare the immune microenvironments (IMEs) of PDAC and its precursor lesions. We demonstrate that the IME of IPMN was abundantly infiltrated with CD8+ T cells and PD-L1-positive antigen-presenting cells (APCs), whereas the IME of PanIN contained fewer CD8+ T cells and fewer PD-L1-positive APCs but elevated numbers of immunosuppressive regulatory T cells (Tregs). Thus, immunosuppression in IPMN and PanIN seems to be mediated by different mechanisms. While immunosuppression in IPMN is facilitated by PD-L1 expression on APCs, Tregs seem to play a key role in PanIN. Our findings suggest potential immunotherapeutic interventions for high-risk precursor lesions, namely, targeting PD-1/PD-L1 in IPMN and CTLA-4-positive Tregs in PanIN to restore immunosurveillance and prevent progression to cancer. Tregs accumulate with malignant transformation, as observed in PDAC, and to a lesser extent in IPMN-associated PDAC (IAPA). High numbers of Tregs in the microenvironment of PDAC went along with a markedly decreased interaction between CD8+ T cells and cancerous epithelial cells (ECs), highlighting the importance of Tregs as key players in immunosuppression in PDAC. We found evidence that a defect in antigen presentation, further aggravated by PD-L1 expression on APC, may contribute to immunosuppression in IAPA, suggesting a role for PD-L1/PD-1 immune checkpoint inhibitors in the treatment of IAPA.

International evidence-based Kyoto guidelines for the management of intraductal papillary mucinous neoplasm of the pancreas

This study group aimed to revise the 2017 international consensus guidelines for the management of intraductal papillary mucinous neoplasm (IPMN) of the pancreas, and mainly focused on five topics; the revision of high-risk stigmata (HRS) and worrisome features (WF), surveillance of non-resected IPMN, surveillance after resection of IPMN, revision of pathological aspects, and investigation of molecular markers in cyst fluid. A new development from the prior guidelines is that systematic reviews were performed for each one of these topics, and published separately to provide evidence-based recommendations. One of the highlights of these new "evidence-based guidelines" is to propose a new management algorithm, and one major revision is to include into the assessment of HRS and WF the imaging findings from endoscopic ultrasound (EUS) and the results of cytological analysis from EUS-guided fine needle aspiration technique, when this is performed. Another key element of the current guidelines is to clarify whether lifetime surveillance for small IPMNs is required, and recommends two options, "stop surveillance" or "continue surveillance for possible development of concomitant pancreatic ductal adenocarcinoma", for small unchanged BD-IPMN after 5 years surveillance. Several other points are also discussed, including identifying high-risk features for recurrence in patients who underwent resection of non-invasive IPMN with negative surgical margin, summaries of the recent observations in the pathology of IPMN. In addition, the emerging role of cyst fluid markers that can aid in distinguishing IPMN from other pancreatic cysts and identify those IPMNs that harbor high-grade dysplasia or invasive carcinoma is discussed.