Intraductal neoplasms of the pancreas encompass a spectrum of epithelial proliferations within the pancreatic ductal system and are broadly classified into flat-type and mass-forming lesions. Flat-type neoplasms, such as pancreatic intraepithelial neoplasia (PanIN), consist of microscopic epithelial changes, whereas mass-forming intraductal neoplasms-including intraductal papillary mucinous neoplasm (IPMN), intraductal oncocytic papillary neoplasm (IOPN), and intraductal tubulopapillary neoplasm (ITPN)-produce clinically or radiologically detectable ductal dilatation or cystic masses. Both categories represent important precursors to invasive pancreatic carcinoma, and accurate classification, grading, and distinction between pseudo-invasion and true invasion remain critical for patient management and prognostication. Gastric-type IPMNs, most often arising in branch ducts, tend to exhibit indolent behavior. Intestinal-type IPMNs, typically involving the main duct and characterized by MUC2 and CDX2 expression, carry a higher risk of progression to invasive colloid carcinoma, which generally has a more favorable outcome. Pancreatobiliary-type IPMNs frequently involve the main duct, express MUC1 and MUC5AC, and more commonly progress to tubular invasive carcinoma resembling pancreatic ductal adenocarcinoma. IOPN and ITPN constitute distinct mass-forming intraductal neoplasms. IOPN typically presents as a large cystic lesion with complex papillary architecture and demonstrates recurrent PRKACA or PRKACB fusions. ITPN is defined by its predominantly tubular growth pattern, mucin-poor phenotype, and absence of MUC5AC expression. Both entities are associated with favorable outcomes following complete resection. Recognition of these intraductal neoplasms is essential, as they must be distinguished from other cystic pancreatic lesions such as mucinous cystic neoplasm (MCN), which is defined by its characteristic ovarian-type stroma.

Neuroendocrine carcinomas of the gallbladder (GBNECs) have been very poorly characterized. In this study, 31 NECs were identified through an analysis of 636 GB cancers and contrasted with the ordinary GBCs (O-GBCs) in the same cohort. Seven were pure small cell NECs, 2 pure large cell, and 22 had mixed adenocarcinoma component (with NEC component being small cell in 6 and large cell in 16). High-grade glandular dysplasia was evident in 15 (6 as intracholecystic neoplasms; vs. 6% in O-GBC), F:M ratio was 5.2:1, and median age was 58 (vs. 65 in O-GBC). The average neuroendocrine component constituted 80% of the tumor; the median Ki-67 was 70%; lymph-vascular invasion was seen in 74%, and perineural invasion in 56%. GBNECs presented with more advanced tumors; 72% were pT3/T4 (vs. 26% in O-GBC, P =0.001). Lymph node metastasis was in 5/10 (with lymph nodes available in the specimen), and 5 had distant metastases. Tumor cells were positive for neuroendocrine markers (synaptophysin 95%, chromogranin 75%, CD56 90%), keratins (AE1/3 90%, Cam5.2 88%), with upper-GI profile (CK7 65%; CK20 0%); TTF-1 in 25%. pRB loss was detected in 67%, positive p16 83%, mutant p53 88.8%, and SMAD4 loss in 24%. Overall, the pRB/p16 pathway was inactivated in 83% (12 [67%] as pRB loss/p16 + , and 3 [17%] as pRB + /p16 − ). DAXX was retained in all. Loss of pRB and p16 was also detected in about a third of the adenocarcinoma and preinvasive components. ATRX loss was noted in 1 large-cell NEC. The median survival was 6.1 months, significantly shorter than O-GBCs, although a few survived unexpectedly longer. Factors associated with shorter survival included pT3 versus pT2 stage, and a trend for lower synaptophysin and CD56 expression. In conclusion, NECs constitute <5% of GBCs, and two-thirds are admixed with an adenocarcinoma component. A fifth arises in intracholecystic neoplasms. Inactivation of the pRB/p16 pathway is common, with 2/3 showing pRB loss. They present as advanced tumors and behave aggressively.

Objective:Postoperative follow-up and treatment decisions after pancreatic cancer surgery are routinely determined by multidisciplinary tumor boards (MDTs), which represent the mainstay of clinical decision-making in these patients. However, this process is associated with increased workload, time consumption, and financial burden. Previous studies have demonstrated improved treatment planning, guideline adherence, and patient outcomes with MDTs, albeit with substantial time, cost, and administrative demands. The present study aims to compare MDT-based decision-making with an artificial intelligence (AI)-assisted model in the postoperative management of patients undergoing surgery for pancreatic cancer and to explore the potential utility of such a model. Materials and methods:An AI-based model was developed using clinical data from 67 patients discussed in multidisciplinary tumor boards between October 2020 and December 2023, in conjunction with current treatment guidelines. The model's recommendations were subsequently compared with MDT decisions in an independent cohort of 15 patients who underwent surgery in 2024. Results:The overall concordance rate between AI-generated recommendations and MDT decisions was 80%. The Cohen's kappa coefficient was 0.625 (95% CI: 0.278-0.972), indicating moderate agreement beyond chance. Three discrepant cases were further analyzed to explore potential reasons for discordance. Discussion:The findings suggest that AI-assisted decision-support systems may approximate MDT recommendations in postoperative pancreatic cancer management. However, observed discrepancies highlight the continued importance of expert clinical judgment and contextual interpretation in complex decision-making scenarios. Conclusion:AI-based models may serve as supportive tools in postoperative clinical decision-making by potentially reducing workload and time burden, but should complement rather than replace multidisciplinary expert evaluation.

Neuroendocrine carcinomas of the gallbladder (GBNECs) have been very poorly characterized. In this study, 31 NECs were identified through an analysis of 636 GB cancers and contrasted with the ordinary GBCs (O-GBCs) in the same cohort. Seven were pure small cell NECs, 2 pure large cell, and 22 had mixed adenocarcinoma component (with NEC component being small cell in 6 and large cell in 16). High-grade glandular dysplasia was evident in 15 (6 as intracholecystic neoplasms; vs. 6% in O-GBC), F:M ratio was 5.2:1, and median age was 58 (vs. 65 in O-GBC). The average neuroendocrine component constituted 80% of the tumor; the median Ki-67 was 70%; lymph-vascular invasion was seen in 74%, and perineural invasion in 56%. GBNECs presented with more advanced tumors; 72% were pT3/T4 (vs. 26% in O-GBC, P=0.001). Lymph node metastasis was in 5/10 (with lymph nodes available in the specimen), and 5 had distant metastases. Tumor cells were positive for neuroendocrine markers (synaptophysin 95%, chromogranin 75%, CD56 90%), keratins (AE1/3 90%, Cam5.2 88%), with upper-GI profile (CK7 65%; CK20 0%); TTF-1 in 25%. pRB loss was detected in 67%, positive p16 83%, mutant p53 88.8%, and SMAD4 loss in 24%. Overall, the pRB/p16 pathway was inactivated in 83% (12 [67%] as pRB loss/p16+, and 3 [17%] as pRB+/p16- ). DAXX was retained in all. Loss of pRB and p16 was also detected in about a third of the adenocarcinoma and preinvasive components. ATRX loss was noted in 1 large-cell NEC. The median survival was 6.1 months, significantly shorter than O-GBCs, although a few survived unexpectedly longer. Factors associated with shorter survival included pT3 versus pT2 stage, and a trend for lower synaptophysin and CD56 expression. In conclusion, NECs constitute <5% of GBCs, and two-thirds are admixed with an adenocarcinoma component. A fifth arises in intracholecystic neoplasms. Inactivation of the pRB/p16 pathway is common, with 2/3 showing pRB loss. They present as advanced tumors and behave aggressively.

We report 6 intraductal papillary squamous neoplasms (IPSNs) of the pancreas, a rare but distinctive tumor whose biological features remain largely unknown. Five cases were investigated using an integrated approach combining histomorphological evaluation, immunohistochemistry, and multiregional molecular profiling through whole-exome DNA sequencing and whole-transcriptome RNA sequencing. Only targeted DNA sequencing was available on a sixth recently diagnosed case. Histologically, the intraductal lesions were characterized by large, confluent papillae with fibrovascular cores lined by multilayered epithelial cells with diffuse squamous differentiation. All cases harbored a concomitant invasive carcinoma. The associated invasive carcinomas consistently included a pancreatic tubular/ductal adenocarcinoma; in 5 cases, a poorly differentiated squamous cell carcinoma was also present, the proportion/features of which met the diagnostic criteria of adenosquamous carcinoma in 2 of them. Genomic analyses revealed that IPSNs and their matched invasive carcinomas shared the majority of somatic alterations, supporting a shared clonal origin for the 2 components. Activating KRAS mutations and biallelic inactivation of CDKN2A were detected in all cases. Recurrent mutations involved members of the SWI/SNF chromatin-remodeling complex and KMT2D. Additionally, FGFR1 and MYC amplifications were identified in 2 distinct cases (1 case each). Molecular alterations restricted to the invasive component involved mediators of the transforming growth factor-β signaling pathway. Transcriptomic profiling demonstrated a basal-like expression pattern in all IPSNs and squamous cell carcinomas, although in 2 cases, the matched pancreatic tubular/ductal adenocarcinoma shifted toward a classical transcriptomic subtype. In conclusion, through integrated histological assessment and multiregional molecular sequencing, we demonstrate that IPSN represents a bona fide precursor of invasive pancreatic cancer, a new addition to the intraductal neoplasms category. This study challenges the current paradigm that pancreatic squamous epithelium plays no role in the initiation of pancreatic carcinogenesis, providing the first evidence of its involvement in early tumorigenic processes and yielding immediate implications for pancreatic tumor classification and biological understanding.

ACTH-producing pancreatic neuroendocrine neoplasms (PanNENs) are a rare aggressive subset of panNETs associated with clinical symptoms of ectopic Cushing syndrome. Until recently, their molecular pathogenesis remained poorly understood. Following our prior study highlighting high frequency of gene fusions (mostly EWSR1::BEND2) in them, we herein document our experience with 5 new tumors occurring in 4 women (one of unspecified sex) aged 36 to 79 (median, 45). All presented with clinical and biochemical signs of ectopic Cushing syndrome. Histologically, the tumors corresponded to NET grade 2 (n = 3) and grade 3 (n = 2). At last follow-up, three patients were alive with metastatic disease at 36, 48 and 72 months from initial diagnosis, one died of disease at 50 months and one was disease-free at 15 months. Targeted RNA sequencing revealed an EWSR1::BEND2 fusion in two cases and a possible CSE1L::TAF15 fusion in one. Two tumors were negative for fusions. This small series and review of the recent literature further confirm the significant association between the EWSR1::BEND2 fusions and ectopic ACTH-production in PanNETs with an overall frequency of ectopic Cushing among EWSR1::BEND2 fusion tumors of 70

Current data on neuroendocrine tumors (NETs) of the gallbladder and cystic duct (GB-NETs) are highly limited, and the available evidence, largely derived from cancer registry data, suggests that these tumors exhibit a substantially more aggressive clinical behavior than NETs arising at other anatomical sites. We analyzed 26 GB-NETs. Female-to-male ratio: 1.9:1; median age: 50 years. They were typically incidental small (median: 0.8 cm, range: 0.08–2.3 cm) tumors, with 81

ABSTRACT Background Pancreatic cancer remains one of the most lethal cancers despite extensive efforts and research conducted over the past decades. To effectuate groundbreaking improvements in pancreatic cancer treatment, interdisciplinary and international collaboration is essential. Evidence‐based guidelines, including state‐of‐the‐art evidence and expert opinion, are crucial to guide medical specialists, researchers, and patients, especially on issues where consensus is still lacking. This article describes the methodological protocol for the development of the European Multidisciplinary Evidence‐Based Guideline on Pancreatic Cancer. The guideline aims to identify current knowledge gaps on pancreatic cancer management, develop questions based on these knowledge gaps, and answer these questions with evidence‐based recommendations supplemented, when evidence is lacking, with expert advice for treatment and future research. Methods This guideline development protocol is developed according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. The process is structured into six stages: First, 13 theme‐based multidisciplinary working groups are established, comprising representatives from 30 European medical and patient societies. Second, these working groups identify the most relevant current knowledge gaps on pancreatic cancer within their theme and formulate key questions. Third, the available evidence to answer these key questions is obtained through systematic reviews and the certainty of evidence is assessed using the GRADE approach. Fourth, recommendations are developed based on the available evidence. Fifth, all participants reach consensus on the recommendations through a modified Delphi process. Sixth, the recommendations are discussed during an open conference, including an external validation committee. Discussion This methodological protocol of the European Multidisciplinary Evidence‐Based Guideline on Pancreatic Cancer is designed to identify key knowledge gaps across 13 themes and formulate evidence‐based recommendations. This guideline initiative unites 30 European medical and patient societies for pancreatic cancer.

AIMS:Acinar cell carcinoma (ACC) is a lineage-specific carcinoma that occurs nearly exclusively in the pancreas. We report, to our knowledge, the first series of gallbladder carcinoma demonstrating extensive acinar differentiation in the absence of a pancreatic primary. METHODS:Three gallbladder carcinomas with extensive acinar differentiation were identified from an international cohort. Clinical, radiologic, macroscopic, histologic, immunophenotypic and molecular features were reviewed. RESULTS:All tumours lacked an associated pancreatic primary on imaging and clinical evaluation. Two tumours formed well-demarcated mural nodules lacking an exophytic mucosal component, while one tumour was associated with wall thickening. The neoplasms showed mural-based infiltrative lesions composed of nests and acinar structures of cells with amphophilic cytoplasm and prominent nucleoli. One tumour arose in association with high-grade dysplasia and BCL10-positive pyloric-type glands. Two tumours showed pure acinar morphology, while one demonstrated a mixed acinar cell carcinoma and small-cell carcinoma. Immunohistochemically, all tumours showed diffuse expression of trypsin, and two tumours showed diffuse BCL10 positivity. Molecular profiling revealed heterogeneous alterations including TP53 mutations in two cases, RB1 inactivation in the mixed tumour. CONCLUSIONS:Gallbladder carcinomas may rarely exhibit acinar differentiation that closely mirrors pancreatic ACC. Recognition of this phenotype expands the morphologic repertoire of gallbladder carcinomas.

Pancreatic neuroendocrine neoplasms (PanNENs) constitute a heterogeneous group of tumors distinguished by substantial variability in morphology, immunophenotype, molecular characteristics, and clinical behavior. In recent years, the advent of multiple omics-based methodologies has significantly enhanced our understanding of these neoplasms. Integrating histology and genomics with survival analyses has clarified that the fundamental distinction within this disease spectrum lies between well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). Furthermore, genomics, transcriptomics, and epigenetic profiling have deepened the granularity of the PanNET landscape, revealing marked differences even within the same diagnostic category, with important clinical implications. For example, DAXX/ATRX mutations, activation of the alternative lengthening of telomeres pathway, BEND2 gene fusions, and an α-cell transcriptional profile are more frequently associated with adverse outcomes. Additional omics approaches, including metabolomics, proteomics, radiomics, and the more recently developed spatially resolved methodologies, are further expanding current knowledge in this challenging field. In this review, we provide an integrated overview of PanNENs, synthesizing insights generated across diverse multi-omics platforms.

Intestinal mucins have extended O-glycans comprised primarily of the common Core 1 O-glycan (Galβ1-3GalNAcα1-Ser/Thr/Tyr) and its modifications. Expression of such glycans is under control of Cosmc (C1GalT1C1) that encodes a key ER molecular chaperone required for formation of active T-synthase, a Golgi enzyme that modifies the Tn antigen (GalNAcα1-Ser/Thr/Tyr - CD175) to generate a Core 1 O-glycan. We previously observed that targeted deletion of Cosmc in murine intestinal epithelial cells (IEC-Cosmc-KO mice) resulted in dysbiosis and alteration of the microbiome. Here we report a detailed description of these mutant mice and find that IEC-Cosmc-KO mice, but not WT mice, express CD175 throughout the intestinal epithelia. CD175 expression is accompanied by loss of glycocalyx, shortening of microvilli, compromised MUC2, thickening of the epithelial layer, as well as generation of high levels of reactive oxygen species. The majority of IEC-Cosmc-/y mice beginning at ∼3 to 9 months spontaneously developed colorectal adenocarcinomas, some with invasive features evidenced by mesenteric metastases, which were potentially associated with activation of TGFβ signaling. Thus, deletion of Cosmc results in expression of CD175 and loss of extended O-glycans in IEC, which is associated with dysregulation of epithelial cell surfaces, leading to spontaneous tumor development.

BACKGROUND:Gallbladder cancer (GBC) is a rare but aggressive disease, and surgical resection remains the only potential curative treatment. Although tumour-related effects on prognosis are well established, the impact of age is less understood. This study aimed to evaluate the influence of age on overall survival (OS), recurrence-free survival (RFS), and perioperative complications in GBC. METHODS:Data from patients undergoing curative resection for GBC at 133 centres across 41 countries between 2010 and 2020 were analysed to determine the prognostic association of age ≥ 75 years with OS, RFS, and morbidity. Propensity score matching was used to address confounders between the two age groups. RESULTS:In all, 4138 patients underwent surgery for GBC. Patients with macroscopic tumour remaining after surgery, metastatic disease, only high-grade dysplasia were excluded leaving 3676 patients for analyses. Full data on all relevant parameters was available for 2072 patients aged < 75 years and 633 patients aged ≥ 75 years. Patients aged ≥ 75 years had more co-morbidities, underwent less extensive surgery or lymphadenectomy, and received adjuvant chemotherapy less frequently than younger (< 75 years) patients. Age ≥ 75 years was associated with poorer OS in both the unmatched (hazard ratio (HR) 1.34; 95% confidence interval (c.i.) 1.14 to 1.56; P < 0.001) and matched cohorts (HR 1.31; 95% c.i. 1.12 to 1.54; P < 0.001) cohorts, but was not associated with RFS or 1-year survival. Tumour extent and nodal stage had the greatest association with OS and RFS. Age was not associated with increased complications in either the unmatched (odds ratio (OR) 1.11; 95% c.i. 0.85 to 1.45; P = 0.400) or matched (OR 0.90; 95% c.i. 0.72 to 1.12; P = 0.353) cohorts. CONCLUSIONS:Older adults received less extensive surgery and infrequent adjuvant chemotherapy. Age ≥ 75 years was associated with poorer OS following GBC resection but comparable complication rates to younger adults. Older adults of sufficient fitness should not be denied curative treatment based on age, and oncological benefit should be balanced against perioperative risk to personalize treatment and optimize surgical outcomes.

The literature is highly conflicting regarding the nature and behavior of pancreatic ductal adenocarcinomas (PDAC) arising from intraductal papillary mucinous neoplasm (IPMN). We investigated and contrasted the clinicopathological features of PDACs associated with IPMN (I-PDAC, n = 52 - only bona-fide and ≥ 1 cm IPMNs along with ordinary pancreatobiliary type invasive adenocarcinomas were included in this group-), versus without (NI-PDAC, n = 390) versus those associated with other IPMN mimicker cysts (pseudo-IPMN-associated, ps-PDAC, n = 39) including retention cysts. In I-PDAC, the average size of the IPMN was 4.05 cm, and 36.5

IMPORTANCE:The lack of multidisciplinary workflow guidelines and clear definitions and classifications for neoplasms in and around the ampulla of Vater results in inconsistencies affecting patient care and research. OBJECTIVE:The PERIPAN international multidisciplinary consensus group aimed to standardize the multidisciplinary diagnostic workflow and achieve consensus on definitions and classifications in order to ensure proper classification and optimal diagnostic assessment and consequently to improve patient care and future research. DESIGN:An international team of 43 experts (pathologists, surgeons, radiologists, gastroenterologists, oncologists) from 12 countries identified knowledge gaps, reviewed 37061 articles, and proposed recommendations using the Scottish Intercollegiate Guidelines Network methodology (SIGN), including the Delphi methodology and the AGREEII tool for quality assessment and external validation. RESULTS:The 38 consensus questions and 51 recommendations provide guidance on the following key aspects: I. More specific anatomic criteria for the definition of what qualifies as "ampullary" neoplasms, their distinction from duodenal and common bile duct tumors, and clinicopathologic characteristics of anatomic subsets; II. Avoidance of the confusing term "periampullary" for final classification; III. Refined definitions of intestinal, pancreatobiliary and mixed subtypes, and introduction of rare histologic subtypes; IV. The use and limitations of immunohistochemical and molecular profiling; V. Biopsy acquisition; VI. Clinical information required for accurate pathology assessment of biopsies and ampullectomy specimens; VII. Key items to be included in pathology reports of endoscopic specimens. CONCLUSIONS AND RELEVANCE:Recognition of the Brescia PERIPAN guidelines will allow a more accurate classification of true ampullary cancers and their differentiation from other "periampullary" tumors. This will have significant implications for endoscopic interpretation and management, staging, pathologic diagnosis and therapeutic evaluation as well as oncologic treatment of various anatomic and histologic subsets of ampullary tumors. This will enhance the quality of both clinical care and future research in this complex medical field.

Gastroenteropancreatic well-differentiated neuroendocrine tumors (NETs) exhibit markedly different behavior and responses to therapy compared to poorly-differentiated neuroendocrine carcinomas (NECs). However, in certain NETs—particularly grade 3 (Ki-67 > 20

Introduction: Pancreatic ductal adenocarcinoma (PDAC) frequently requires neo-adjuvant therapy, leaving cytologic preparations – especially endoscopic ultrasound-guided fine-needle aspiration smears – as the only naïve tissue available for molecular testing. However, their applicability remains underappreciated due to limited data and concerns about specimen adequacy. This study aimed to evaluate the feasibility of performing molecular analysis on cytologic smears to detect targetable alterations in PDAC. Methods: Molecular analysis was conducted on 120 PDAC samples: 41 cytology specimens, 50 core biopsies, and 29 resections. KRAS mutations and homologous recombination repair gene alterations were assessed. Rapid on-site evaluation guided triage in all FNA cases. DNA and RNA isolations were performed, followed by quality control (QC) assessment and sequencing. Results: DNA isolation succeeded in 92/95 cases (97%), with a 100% success rate in cytologic specimens. RNA isolation passed QC in 71/84 samples (83%), with failures more common in smears (n = 8). KRAS mutations were detected in 71/85 patients (82%), with the highest detection in cytologic specimens (92%) compared to biopsies (78%) and resections (80%). Conclusion: Molecular testing is feasible and may even be more successful in cytologic smears than in biopsies or resections. High diagnostic yield and rapid processing favor their integration into routine molecular workflows. The superior performance of smears may relate to reduced stromal content and minimal processing delays. Cytologic specimens showed 100% DNA QC success, even when RNA QC failed, supporting their reliability. Although RNA analysis had a modest failure rate, its overall success suggests it can be incorporated into routine testing, particularly as fusion-driven targets gain clinical relevance.

The pivotal role of Ki67 in grading pancreatic neuroendocrine tumors (PanNETs) is well recognized and firmly established in current WHO guidelines. Intratumoral heterogeneity is a well-known phenomenon, and it has also been documented for Ki67; however, the data on the magnitude of the impact of this heterogeneity on the final grade in primary NETs is relatively limited. In this study, Ki67 labeling index (KI) was calculated by using the manual count of camera-captured image method in 91 PanNETs both in hot-spots (KI(h)) as well as 6 different random-areas (KI(r)), each counted in a minimum of 2000 cells. The process was repeated for 29 samples from metastatic foci. Mean KI of the hot-spots was more than twofold higher than that of the random (5 vs 2.1