Ampullary adenocarcinoma (AMPAC) is a rare and heterogeneous malignancy with markedly variable clinical outcomes, underscoring the urgent need for molecularly informed classification and personalized therapeutic strategies. Current AMPAC classification relies primarily on morphological and immunohistochemical criteria, which lack prognostic accuracy and fail to capture the underlying molecular and tumor microenvironment heterogeneity. In this study, we integrated bulk RNA sequencing, single-cell RNA sequencing (scRNA-seq), and clinicopathological data to elucidate the molecular architecture of AMPAC and introduced a transcriptomic-based molecular classification (AMS). The AMS categorized patients into two molecular subtypes: mesenchymal AMPAC (AMS-M) and classical AMPAC (AMS-C). The AMS-M demonstrated increased epithelial-mesenchymal transition (EMT) and stromal activation, correlating with basal-like subtypes associated with unfavorable prognosis. In contrast, AMS-C tumors exhibited metabolic and differentiation programs with relatively preserved immune infiltration. Importantly, we identified MUC16 as a pivotal biomarker specifically overexpressed in AMS-M tumors. MUC16 knockout markedly reversed EMT, attenuated invasive and migratory capacities, and restored chemosensitivity in both cell lines and their xenograft models. Collectively, our findings establish AMS as a prognostically and therapeutically informative molecular classification framework for AMPAC, unveil the critical role of the tumor microenvironment in AMPAC heterogeneity, and provide a translational foundation for precision oncology in this rare tumor.

Neoplasia-related extrahepatic biliary obstruction (EHBO) is rare in dogs. An 11-year-old spayed mixed-breed dog had intermittent jaundice for several months. Imaging showed a lesion extending from the distal common bile duct to the major duodenal papilla. To relieve EHBO, transduodenal ampullectomy was performed, followed by partial duodenectomy including the papillary orifice and cholecystoduodenostomy. Histopathological examination revealed ampullary adenocarcinoma with invasion into the duodenal muscularis propria; margins were tumor-free. At >2 years after surgery, metastasis was not detected, and the dog remained clinically well. To our knowledge, this is the first report of canine ampullary carcinoma, suggesting that transduodenal ampullectomy can be useful for both palliative biliary decompression and the assessment of invasion depth to guide subsequent definitive surgery.

Ampullary carcinoma is an uncommon malignant neoplasm located in Vater's ampulla, necessitating comprehensive exploration of its pathogenesis and therapeutic alternatives. Currently, the available models of ampullary carcinoma are severely restricted, impeding the advancement of fundamental research. Consequently, further models of ampullary carcinoma are required to enhance pertinent fundamental research. This study reports the development of a novel Chinese-origin human ampullary carcinoma cell line, named DPC-X2, utilizing fresh primary tumor tissue from ampullary carcinoma. DPC-X2 has been consistently passaged for more than 60 generations, exhibiting a population doubling time of around 95 h. The cells display atypical shape and distinct heterogeneity. STR profiling verifies that DPC-X2 is a unique human ampullary carcinoma cell line. Karyotype analysis indicates that all DPC-X2 cells have hyper-triploid karyotypes, characterized by a typical karyotype of 100, XXXX der(4), der(6), der(7), inv(9), der(12), der(13), der(19). The xenograft tumor development rate in NXG mice was 66.67%. This cell line exhibits sensitive to gemcitabine while demonstrating resistance to oxaliplatin, fluorouracil, and albumin-bound paclitaxel. DPC-X2 may be an important model for investigating the pathogenesis of ampullary carcinoma and for pharmaceutical development research.

A 79-year-old female patient with dynapenia was diagnosed with duodenal ampullary cancer (cT1a, cN0, cM0, cStage Ⅰ) and underwent pancreaticoduodenectomy. Postoperatively, she experienced complications, a decline in her ability to perform activities of daily living and required long-term hospitalization. Dynapenia is defined as an age-related decline in muscle strength that occurs before the loss of muscle mass. In contrast, sarcopenia refers to the age-related loss of muscle or lean mass. Both conditions contribute to the decline of active and healthy aging. Dynapenia plays a significant role in the loss of physical function and increased risk of postoperative complications in highly invasive surgery like pancreaticoduodenectomy.

Lymph node ratio (LNR) has emerged as a strong prognostic indicator in colorectal cancer (CRC), but its significance in non-ampullary primary small intestine adenocarcinoma (SIA) has been only sparsely reported in the literature. Moreover, LNR has not been examined alongside key CRC histologic prognostic variables, including tumor budding (TB), desmoplastic reaction (DR), and tumor-infiltrating lymphocytes (TILs). Eighty-nine cases (mean age: 63 years, range: 20-88) of SIA were included from 2008 to 2023; most tumors arose in the duodenum (40%). Mean follow-up was 40.9 months (range: 0-189). The mean carcinoembryonic antigen (CEA) level was 38.4 ng/mL (range: 0.2-1183.9). Low-grade histology predominated (69%), and lymphovascular invasion was seen in 42% and perineural invasion in 16%. TB was low in 55%, intermediate in 30%, and high in 15%. DR was mature in 45%, intermediate in 43%, and immature in 12%. TILs were present in 34%. The average International TILs Working Group score was 29% (range: 0-80%). The mean LNR was 0.2, and 49% of cases were pN0. Most tumors were pT3 (54%) or pT4 (34%), and 12% were pM1. Only CEA level and LNR independently predicted disease-free survival (HR: 1.01; 95%CI 1.00-1.02; P = 0.010 and HR 14.64; 95%CI 1.82-117.59; P = 0.012, respectively), and LNR independently predicted overall survival (HR 14.55; 95%CI 1.76-120.06; P = 0.013). Higher LNR was significantly associated with adverse tumor characteristics, including features of the tumor microenvironment such as TB, DR, and TILs. LNR and pre-operative CEA level outperformed nodal stage and other histologic factors as prognostic markers in SIA.

Rare tumor diseases are difficult to diagnose and there is a lack of routine diagnostic procedures. Approaches must be found that allow comprehensive identification and evaluation of prognostic relevant target proteins or transcripts. Analyzing rare ampullary cancer, respectively, to their prognosis and predictive factors by machine learning (ML) based matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) imaging is a first step towards providing new solutions for diagnostics of those cancer samples. In this study, we investigated a cohort of ampullary adenocarcinomas, including intestinal, pancreatic and cases of unknown subtypes, to identify differences in the proteome. Human formalin-fixed paraffin-embedded (FFPE) tissues were pathologically assessed, immunohistological stained, MALDI Imaging detected, and ML-related analyzed. We enable MALDI imaging as a diagnostic complement for immunohistochemical analysis and provide a MALDI Imaging neural network for broad application in tumor diagnostics. Moreover, using tools from ML model explainability, we determined a small subset of influential m/z-values from the trained models. The transformation of locally established ML networks dependent on one proteomic application source to other similar application sources (without peak picking or other pre-processing) is the basis for future rare cancer patient data collection.

Neuroendocrine differentiation is a common feature observed in epithelial tumors. Both exocrine and neuroendocrine differentiation can be observed in tumors originating from the gastrointestinal system. However, since 1924, these tumors have been described under different names, leading to confusion among clinicians. While such tumorsare generally referred to as mixed adenocarcinoma-neuroendocrine carcinoma in the 4th WHO classification, amphicrine tumors are not currently included in any specific tumor classification. This study aimed to enhance the understanding of the clinicopathological features of amphicrine tumors, thus contributing to their standardized classification. A 52-year-old woman presented to our center with persistent nausea and vomiting. Physical examination revealed no findings except tenderness in the right upper quadrant of the abdomen. Intraoperative consultation revealed a tumor, approximately 8 mm in diameter, in the ampullary region. A tumor showing neuroendocrine differentiation was observed in the hematoxylin and eosin-stained sections. After formalin fixation, tumors with neuroendocrine differentiation were observed in the sections. Trabecular and glandular patterns, and nuclear salt-and-pepper chromatin were observed in the tumor cells. Immunohistochemically, the tumor cells were positive for synaptophysin and chromogranin. Alcian blue staining was positive for cytoplasmic mucin, and diffuse CDX2 expression was observed. As a result, the diagnosis was confirmed as "amphicrine carcinoma." Based on these findings, this type of tumor should be included as a separate histological type from adenocarcinomas, neuroendocrine carcinomas, and mixed neuroendocrine-nonneuroendocrine neoplasm. This will also support a more standardized approach in terms of the treatment and follow-up protocols for patients with this rare tumor.

PURPOSE: Periampullary, pancreatic ductal, distal bile duct and duodenal carcinomas have overlapping gross presentation and morphology. Exact site of origin is often difficult to establish conclusively, yet they have differing AJCC TNM staging systems. This makes grossing Whipple’s specimens daunting in centers with limited volume, increasing the chance of inaccurate staging. The aim of this study is to validate an alternative size-based staging system for ampullary cancers, using pancreatic ductal adenocarcinoma staging characteristics, which can simplify pathological assessment of Whipple’s specimens. METHODS: Clinicopathologic data from all consecutive patients of ampullary adenocarcinoma were retrospectively reviewed. Prognostic correlation of this alternative size-based staging system (using cut-offs of 2 and 4 cm) was done with disease free survival (DFS) and overall survival (OS). This alternative staging proposal was compared with the current AJCC8 tumour staging system and other histological prognostic parameters. RESULTS: After applying exclusion criteria, 146 cases were analyzed in this study. The tumor size-based stage did not correlate significantly with DFS (p = 0.4) or OS (p = 0.3), but the AJCC8 T stage did (p = 0.03). Multivariate analysis using both AJCC T stage and size-based categorization, also did not show any prognostic correlation with outcome, though positive surgical margins, perineural invasion and the pN2 nodal status were established as independent prognostic factors. CONCLUSIONS: Tumor size-based staging (using pancreatic ductal cancer criteria) is currently inferior to AJCC TNM stage for ampullary carcinoma and needs further evaluation in large multi-institutional studies.

Small intestine adenocarcinomas (SIACs) in humans occur predominantly as extra-ampullary SIAC [SIAC/extra-ampullary duodenal adenocarcinoma (EDA)], demonstrate intestinal- or gastric-type differentiation, and arise from precursor adenomas. The aims of this study were to determine spatial transcriptomics of SIAC/EDA differentiation subtypes and driver molecular pathways in humans and novel mouse models. Spatial transcriptomics and immunohistochemistry were performed in human and murine SIAC/EDA and adenomas. Mice with Cdkn2a/p16 conditional knockout, KrasG12D expression, or both (p16KOKrasG12D) targeting leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) cell progenitors were generated, and histologic alterations were examined. Spatial transcriptomics identified differentiation signatures of intestinal and gastric-type SIAC/EDA and adenomas, their microenvironment, cell-cell signaling interactions driving neoplasia progression, and susceptibility to targeted therapies. Activated signaling pathways were not specific to differentiation subtype. Algorithm-inferred susceptibility to mitogen-activated protein kinase kinase (MEK) inhibitors correlated with activation of MEK pathways in gastric-type SIAC. p16KOKrasG12D mice developed small intestine/duodenal adenomas by 11 to 15 months (10/14, 83%), and adenocarcinomas by 12 to 19 months, in contrast to wild-type mice (P = 0.0003). Spatial transcriptomics of mouse lesions largely replicated human SIAC/EDA differentiation signatures and signaling pathways. A novel genetically engineered mouse model that mimics gastric- and intestinal-type adenomas and gastric-type SIAC/EDA is reported. Spatial transcriptomics provided a detailed understanding of cellular differentiation lineages, cancer microenvironment related to SIAC subtypes, and driving pathways that may be leveraged to identify new molecular tools for pathologic diagnosis and potential targets for precision cancer therapies.

Ampullary carcinoma (AC) is a rare gastrointestinal malignancy with dual intestinal and pancreatobiliary differentiation, complicating diagnosis, staging, and treatment. This review synthesizes current epidemiology, pathology, and multi-omic data to outline a pragmatic care pathway: lineage-first at presentation, mutation-fast at progression. Histology remains the primary classifier: the intestinal subtype generally aligns with colorectal regimens, whereas pancreatobiliary and mixed subtypes favor pancreaticobiliary therapy. In selected fit patients, modified FOLFIRINOX may address mixed phenotypes. Next-generation sequencing adds precision by identifying therapeutically relevant alterations, including ERBB2/HER2 amplifications, MSI-high/dMMR, BRAF V600E, and rare NTRK or RET fusions, while KRAS mutations are enriched in pancreatobiliary tumors. We recommend early application of a rapid-core panel (KRAS/BRAF, MSI/dMMR, ERBB2/HER2, RNA-based fusions) to capture high-impact targets, followed by comprehensive profiling at first progression. Liquid biopsy, plasma circulating tumor DNA (ctDNA), or bile-derived DNA may complement tissue and help identify the dominant lineage. Research priorities include ampulla-enriched umbrella trials, explicit AC subcohorts in tissue-agnostic studies, and ctDNA-informed endpoints. This lineage-first, mutation-fast paradigm supports precision care and evidence generation in AC.