Gastrointestinal Pathologists Research Articles

Sex differences in the colorectal tumor immune microenvironment.

283 Background: Males have increased risk and mortality rates of colorectal cancer (CRC) compared to females, but the reasons for these disparities are not well understood. Immune responses differ by sex, and a robust T cell response is an important prognostic indicator in CRC. We hypothesized that females exhibit a stronger CRC-associated T cell response, contributing to reduced mortality in females compared to males. Methods: The study cohort included 2,751 incident CRC patients (1,337 female; 1,414 male) from a population-based case-control study. T cell receptor (TCR) abundance and clonality were quantified using immunoSEQ, and a gastrointestinal pathologist scored tumor-infiltrating lymphocyte counts per high-powered field (TILs/hpf). We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between T cell metrics and sex, adjusting for age, anatomic site, and microsatellite instability (MSI) status. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals for the association between sex and 5-year all-cause and CRC-specific survival, adjusting for known prognostic indicators. We also conducted a formal test for interaction between sex and T cell features in relation to survival outcomes. Results: There were no associations between sex and TCR abundance (OR=1.05, 95% CI=0.98-1.13, p=0.14), TCR clonality (OR=0.99, 95% CI=0.91-1.06, p=0.72), or TILs/hpf (OR=1.05, 95% CI=0.88-1.25, p=0.60). We observed no differences in overall or disease-specific five-year survival between males and females. Further, the associations between T cell responses and survival did not significantly differ by sex. Conclusions: In a well-powered analysis, no robust sex differences were observed in the CRC immune microenvironment or in the relationship between T cell infiltration and CRC outcomes. The high burden of CRC and the emergence of immunotherapy as an important therapeutic approach suggest a need for further research investigating immunological sex differences in the setting of treatment response. Summary of associations between the colorectal tumor T cell response and sex. T cell Features Odds Ratio(Female vs. Male) Lower 95% CI Upper 95% CI P Value TCR Abundance 1.05 0.98 1.13 0.14 TCR Clonality 0.99 0.91 1.06 0.72 TILs/hpf* <2 1.05 0.88 1.25 0.60 *A total of 99 patients (45 female; 54 male) with missing TILs/hpf data were excluded from the regression analysis.

Interobserver agreement and practice patterns for grading of colorectal carcinoma: World Health Organization (WHO) classification of tumours 5th edition versus American Joint Committee on Cancer (AJCC) 8th edition staging manual.

The current American Joint Committee on Cancer (AJCC) staging manual and the College of American Pathologists (CAP) colorectal carcinoma (CRC) protocol specify use of a four-tiered grading system (i.e. grades 1-4; well-differentiated-undifferentiated) for CRC, based on percentage of gland formation. The World Health Organization (WHO) 5th edition grades CRC into low-grade (well- and moderately differentiated) and high-grade (poorly and undifferentiated), based on the least differentiated component. We studied interobserver agreement and practice patterns among pathologists when grading CRC by these two grading systems. Five gastrointestinal pathologists reviewed 100 scanned CRC slides and graded the tumour on each slide, per provided criteria in (a) WHO 5th edition book, (b) AJCC manual/CAP CRC protocol and (c) their clinical practice. A questionnaire for grading selected CRC subtypes was also provided. Statistical analysis was performed using Pearson's χ2 test and Fleiss multi-rater kappa analyses. Overall, agreement among the five reviewers when grading via WHO and AJCC criteria for low-grade and high-grade CRC was moderate (κ = 0.568, P < 0.001) and good (κ = 0.611, P < 0.001), respectively. All reviewers graded significantly more tumours as high-grade when using WHO (median = 46) versus AJCC/CAP criteria (median = 20). Interobserver agreement was higher using the AJCC grading criteria as a two-tiered system. Significantly more tumours were called high-grade using the WHO criteria. This raises concerns regarding upgrading tumours, as well as potential differences in grading tumours among pathologists worldwide, based on regional preferred grading systems. Synchronisation of these two grading systems is necessary for uniform grading of CRCs throughout institutions.

P1083 Biological therapy and histological tumor necrosis factor - alpha expression in Inflammatory Bowel Disease patients

Abstract Background Tumor necrosis factor alpha (TNF-alpha) is crucial in IBD pathogenesis: previous studies showed that its expression correlates to the degree of colonic inflammation and that its issue levels may predict response to biologic agents. This project addresses immunohistochemical (IHC) TNF-alpha expression profiles and patterns in ileal, colonic, and rectal biopsies before and after biologic therapy, matched with endoscopic and clinical severity indexes. Thus, this study aims to identiy possible histological and IHC markers predictive of drug response. Methods A cohort of ten patients with Inflammatory Bowel Disease (7 Crohn’s Disease and 3 Ulcerative Colitis) treated with biologic agents were phenotypically defined according to the Montreal classification and retrospectively characterized as responders or non- responders. These features were pioneeringly integrated with IHC quantiying TNF-alpha positivity and endoscopic severity scores (SES-CD, Mayo endoscopic subscore) aHer the collection of colonoscopy biopsy specimens. IHC TNF-alpha assessment evidenced pronounced cytoplasmic staining of inflammatory cells in the lamina propria amidst crypts and occasionally with a transmural distribution. Elevated TNF-alpha positive cells (arbitrary cut-off of ≥ 20) were chiefly observed at diagnosis or relapse in the intestinal segments affected by the disease. Results For each colonoscopy, endoscopic activity (SES-CD/Mayoendoscopic score) significantly correlated with the dichotomic number of TNF-alpha+ cells measured in the biopsies at the endoscopic (ESOD) and histologic (HSOD) site of disease (p=0,039; p=0,046). Furthermore, the number of TNF-alpha positive cells in the HSOD segment at the first check-up available during treatment was significantly associated with response to first-line biologics (p= 0,023), thus suggest whether treatment continuation was appropriate or not. Conclusion This study thoroughly examines the link between IHC investigation of TNF-alpha positivity, Montreal classification at diagnosis, and endoscopic activity indexes. TNF-alpha IHC analysis could further stratify IBD patients and increase diagnostic accuracy, securing a patent- and disease-tailored therapy and avoiding unnecessary and ineffective treatments. As an outcome, it could reduce fruitless health expenditures resulting from failed therapeutic attempts. Lastly, this evaluation could spark new possibilities for molecular biology research regarding TNF-alpha functionality on the ileocolon and further elucidate the mechanisms underlying IBD. References Villanacci V et al "Histopathology of inlammatory bowel disease- Position statement of the Pathologists of the Italian Group of the Study of the Inflammatory Bowel Disease (IG- IBD) and Italian Group of Gastrointestinal Pathologists (GIPAD-SIAPEC) " Digestive ad Liver Disease 2020 Daperno et al . "Development and validation of a new, simplified endoscopic activity score of Crohn’s Disease: the SES - CD" GIE 2002

Deep Learning for Classification of Inflammatory Bowel Disease Activity in Whole Slide Images of Colonic Histopathology.

Grading activity of inflammatory bowel disease (IBD) using standardized histopathological scoring systems remains challenging due to limited availability of pathologists with IBD expertise and inter-observer variability. In this study, a deep learning model was developed to classify activity grades in hematoxylin and eosin-stained whole slide images (WSIs) from patients with IBD, offering a robust approach for general pathologists. This study utilized 2,077 WSIs from 636 patients who visited Dartmouth-Hitchcock Medical Center in 2018 and 2019, scanned at 40× magnification (0.25 μm/pixel). Board-certified gastrointestinal pathologists categorized the WSIs into four activity classes: inactive, mildly active, moderately active, and severely active. A transformer-based model was developed and validated using five-fold cross-validation to classify IBD activity. Using HoVerNet, neutrophil distribution across activity grades was examined. Attention maps from the model highlighted areas contributing to its prediction. The model classified IBD activity with weighted averages of 0.871 [95% Confidence Interval (CI): 0.860-0.883] for the area under the curve, 0.695 [95% CI: 0.674-0.715] for precision, 0.697 [95% CI: 0.678-0.716] for recall, and 0.695 [95% CI: 0.674-0.714] for F1-score. Neutrophil distribution was significantly different across activity classes. Qualitative evaluation of attention maps by a gastrointestinal pathologist suggested their potential for improved interpretability. The model demonstrates robust diagnostic performance and could enhance consistency and efficiency in IBD activity assessment.

Unravelling interobserver variability in gastrointestinal glandular neoplasia: a contemporary study of US and Korean pathologists

AimsInterobserver variability in the assessment of gastric neoplasia biopsies between most Western and Eastern (predominantly represented by Japanese in the literature) pathologists has been documented. It is unknown if such...

Deformable Mapping of Rectal Cancer Whole-Mount Histology with Restaging MRI at Voxel Scale: A Feasibility Study.

Purpose To develop a radiology-pathology coregistration method for 1:1 automated spatial mapping between preoperative rectal MRI and ex vivo rectal whole-mount histology (WMH). Materials and Methods This retrospective study included consecutive patients with rectal adenocarcinoma who underwent total neoadjuvant therapy followed by total mesorectal excision with preoperative rectal MRI and WMH from January 2019 to January 2022. A gastrointestinal pathologist and a radiologist established three corresponding levels for each patient at rectal MRI and WMH, subsequently delineating external and internal rectal wall contours and the tumor bed at each level and defining eight point-based landmarks. An advanced deformable image coregistration model based on the linearized iterative boundary reconstruction (LIBR) approach was compared with rigid point-based registration (PBR) and state-of-the-art deformable intensity-based multiscale spectral embedding registration (MSERg). Dice similarity coefficient (DSC), modified Hausdorff distance (MHD), and target registration error (TRE) across patients were calculated to assess the coregistration accuracy of each method. Results Eighteen patients (mean age, 54 years ± 13 [SD]; nine female) were included. LIBR demonstrated higher DSC versus PBR for external and internal rectal wall contours and tumor bed (external: 0.95 ± 0.03 vs 0.86 ± 0.04, respectively, P < .001; internal: 0.71 ± 0.21 vs 0.61 ± 0.21, P < .001; tumor bed: 0.61 ± 0.17 vs 0.52 ± 0.17, P = .001) and versus MSERg for internal rectal wall contours (0.71 ± 0.21 vs 0.63 ± 0.18, respectively; P < .001). LIBR demonstrated lower MHD versus PBR for external and internal rectal wall contours and tumor bed (external: 0.56 ± 0.25 vs 1.68 ± 0.56, respectively, P < .001; internal: 1.00 ± 0.35 vs 1.62 ± 0.59, P < .001; tumor bed: 2.45 ± 0.99 vs 2.69 ± 1.05, P = .03) and versus MSERg for internal rectal wall contours (1.00 ± 0.35 vs 1.62 ± 0.59, respectively; P < .001). LIBR demonstrated lower TRE (1.54 ± 0.39) versus PBR (2.35 ± 1.19, P = .003) and MSERg (2.36 ± 1.43, P = .03). Computation time per WMH slice for LIBR was 35.1 seconds ± 12.1. Conclusion This study demonstrates feasibility of accurate MRI-WMH coregistration using the advanced LIBR method. Keywords: MR Imaging, Abdomen/GI, Rectum, Oncology Supplemental material is available for this article. © RSNA, 2024.

Pathologist Workload Assessment in Gastrointestinal Subspecialty: A Pilot comparative study in an academic setting

Abstract Introduction/Objective There are no official guidelines regarding the workload to be received by pathologists, and it is challenging to distribute equivalent workloads across subspecialties. This study aims to determine whether slide count is a reliable workload metric in gastrointestinal (GI) pathology. Additionally, we seek to compare the time allocation differences between GI pathologists involved in medical resident teaching and those dedicated only to anatomical pathology duties. Methods/Case Report This is an observational retrospective cohort study. We recorded the first two hours of a workday of three experienced GI pathologists at Stanford Healthcare in 2022, two of whom were engaged in teaching. The authors carefully retrospectively reviewed the recorded videos to extract relevant information: teaching activities, number of histological slides, specimens, types of tissues analyzed, and resultant diagnosis. Results (if a Case Study enter NA) Two attendings (2 and 3) signed out with residents, while only one worked alone (1). The mean time spent on each case was 199 and 486 seconds different between attendings 1 and 2 and 1 and 3, respectively (p&amp;lt;.01). There was a strong positive correlation between the number of slides and time spent analyzing each case, r =.607. The number of slides per case statistically explained 36.8% of the time spent per case, p &amp;lt;.001. Conclusion In conclusion, the slide count metric only explains 36.8% of the time expenditure, suggesting that more sophisticated workload assessment methods must be developed, particularly if used for workload distribution purposes. Also, GI pathologists involved in medical training take longer to sign out cases than GI pathologists who are not, suggesting that this is an essential factor that should be considered when distributing workloads.

Histopathology underlying environmental enteric dysfunction in a cohort study of undernourished children in Bangladesh, Pakistan, and Zambia compared with United States children

BackgroundEnvironmental enteric dysfunction (EED) is an asymptomatic intestinal disorder associated with growth impairment, delayed neurocognitive development, and impaired oral vaccine responses. ObjectivesWe set out to develop and validate a histopathologic scoring system on duodenal biopsies from a cohort study of children with growth failure in Bangladesh, Pakistan, and Zambia (“EED”) with reference to biopsies from United States children with no clinically reported histologic pathology (referred to hereafter as “normal”) or celiac disease. MethodsFive gastrointestinal pathologists evaluated 745 hematoxylin and eosin slide images from 291 children with EED (mean age: 1.6 y) and 66 United States children (mean age: 6.8 y). Histomorphologic features (i.e., villus/crypt architecture, goblet cells, epithelial and lamina propria acute/chronic inflammation, Brunner’s glands, Paneth cells, epithelial detachment, enterocyte injury, and foveolar metaplasia) were used to score each histopathologic slide. Generalized estimating equations were used to determine differences between EED, normal, and celiac disease, and receiver operating characteristic curves were used to assess predictive value. ResultsBiopsies from the duodenal bulb showed higher intramucosal Brunner’s gland scores and lower intraepithelial lymphocyte scores than from the second or third parts of the duodenum (D2/3), so only D2/3 were included in the final analysis. Although 7 parameters differed significantly between EED and normal biopsies in regression models, only 5 (blunted villus architecture, increased intraepithelial lymphocytosis, goblet cell depletion, Paneth cell depletion, and reduced intramucosal Brunner’s glands) were required to create a total score percentage (TSP-5) that correctly identified EED against normal biopsies (AUC: 0.992; 95% CI: 0.983, 0.998). Geographic comparisons showed more severe goblet cell depletion in Bangladesh and more marked intraepithelial lymphocytosis in Pakistan. ConclusionsThis scoring system involving 5 histologic parameters demonstrates very high discrimination between EED and normal biopsies, indicating that this scoring system can be applied with confidence to studies of intestinal biopsies in EED.

Preinjection With Ligation-Assisted Endoscopic Mucosal Resection for Barrett's Dysplasia and Early Esophageal Adenocarcinoma: Characteristic Histological Features of the Depth of Resection.

Endoscopic mucosal resection (EMR) is an established technique for the diagnosis and treatment of high-grade dysplasia (HGD) and early esophageal adenocarcinoma (EAC) in Barrett's esophagus. Submucosal preinjection is not universally used or generally recommended when performing routine ligation-assisted EMR. Prior studies, however, have demonstrated evidence of at least superficial muscle injury on ligation-assisted EMR without submucosal injection. There are limited published data supporting any potential benefit of submucosal preinjection. Our aim was to review this technique and determine the rate of any degree of muscle injury in patients with Barrett's HGD and EAC treated with submucosal preinjection before ligation-assisted EMR. Patients undergoing submucosal preinjection before ligation-assisted EMR for Barrett's esophagus at a single institution between 2012 and 2016 were identified. Data were collected regarding patient demographics and medical history, endoscopy and histopathology findings, adverse events, and subsequent outcomes. All EMR specimens were reviewed by an expert gastrointestinal pathologist. One hundred fifty consecutive EMR procedures were performed on 70 patients. Of 70 patients, 85.7% of patients were men, with a median age of 68 years. EAC was identified in 75 specimens (50%) and HGD in 44 specimens (29.3%). Deep resection margins were clear of adenocarcinoma in all specimens. Muscularis propria was not identified in any of the 150 specimens. There were no cases of post-EMR perforation. Preinjection before ligation-assisted EMR achieved complete excision with histologically clear margins, without histological evidence of any inadvertent muscularis propria.

Histopathological comparison of colorectal neoplasia or polyps development between young adults and older adults: Our experience of 735 consecutive cases and 1269 polyps.

In recent decades, there has been an increase in early-onset colorectal cancer, the need to screen individuals younger than 50 years of age, and the presence of histopathological differences remains unclear. The objective of this study was to explore the occurrence of polyps in both young adults and older individuals and to examine their potential correlation with colorectal cancer. In this retrospective study conducted between July 1, 2018, and October 5, 2022, in the Pathology Laboratory, we designed a study based on the histopathological features of colorectal polyps evaluated by an experienced gastrointestinal pathologist based on the WHO 2019 classification. We evaluated 735 consecutive patients who underwent colonoscopic polypectomy between July 2018 and October 2022. The prevalence of cases under the age of 50 was 13.9%, and adults over the age of 50 was 86.1%. A total of 1269 polyps were detected, 1215 (95.7%) were epithelial polyps and 145 (11.9%) were epithelial polyps under the age of 50. One hundred four conventional adenomas and four intramucosal carcinomas were detected in cases younger than 50 years. The patients in the low-risk adenoma group was 57%, and the rate of patients in the high-risk adenoma group was 14.9%. Overall, polyps were most common in the sigmoid colon and there was a statistically significant difference between detecting tubular adenomas in the sigmoid colon (P=0.04). Our current results confirm the detection of sporadic colorectal adenomas and advanced neoplasia in young adults.It is important to establish professional community guidelines for surveillance colonoscopy in these age groups.

Genomic Profiling of Rare Undifferentiated Sarcomatoid Subtypes of Pancreatic Carcinomas: In Search of Therapeutic Targets

PURPOSE The highly aggressive undifferentiated sarcomatoid carcinoma (USC) subtype of pancreatic ductal adenocarcinoma (PDAC) remains poorly characterized because of its rarity. Previous case reports suggest that immune checkpoint inhibitors could be a promising treatment strategy, but the prevalence of established predictive biomarkers of response is largely unknown. The objective of this study was to leverage comprehensive genomic profiling of USC PDAC tumors to determine the prevalence of biomarkers associated with potential response to targeted therapies. METHODS USC tumors (n = 20) underwent central pathology review by a board-certified gastrointestinal pathologist to confirm the diagnosis. These samples were compared with non-USC PDAC tumors (N = 5,562). Retrospective analysis of DNA and RNA next-generation sequencing data was performed. RESULTS USC PDACs were more frequently PD-L1+ by immunohistochemistry than non-USC PDAC (63% v 16%, respectively, P &lt; .001). Furthermore, USC PDAC had an increase in neutrophils (8.99% v 5.55%, P = .005) and dendritic cells (1.08% v 0.00%, q = 0.022) and an increased expression of PDCD1LG2 (4.6% v 1.3%, q = 0.001), PDCD1 (2.0% v 0.8%, q = 0.060), and HAVCR2 (45.9% v 21.7%, q = 0.107) than non-USC PDAC. Similar to non-USC PDAC, KRAS was the most commonly mutated gene (86% v 90%, respectively, P = 1). CONCLUSION To our knowledge, this work represents the largest molecular analysis of USC tumors to date and showed an increased expression of immune checkpoint genes in USC tumors. These findings provide evidence for further investigation into immune checkpoint inhibitors in USC tumors.

Germline genetic regulation of the colorectal tumor immune microenvironment

ObjectiveTo evaluate the contribution of germline genetics to regulating the briskness and diversity of T cell responses in CRC, we conducted a genome-wide association study to examine the associations between germline genetic variation and quantitative measures of T cell landscapes in 2,876 colorectal tumors from participants in the Molecular Epidemiology of Colorectal Cancer Study (MECC).MethodsGermline DNA samples were genotyped and imputed using genome-wide arrays. Tumor DNA samples were extracted from paraffin blocks, and T cell receptor clonality and abundance were quantified by immunoSEQ (Adaptive Biotechnologies, Seattle, WA). Tumor infiltrating lymphocytes per high powered field (TILs/hpf) were scored by a gastrointestinal pathologist. Regression models were used to evaluate the associations between each variant and the three T-cell features, adjusting for sex, age, genotyping platform, and global ancestry. Three independent datasets were used for replication.ResultsWe identified a SNP (rs4918567) near RBM20 associated with clonality at a genome-wide significant threshold of 5 × 10− 8, with a consistent direction of association in both discovery and replication datasets. Expression quantitative trait (eQTL) analyses and in silico functional annotation for these loci provided insights into potential functional roles, including a statistically significant eQTL between the T allele at rs4918567 and higher expression of ADRA2A (P = 0.012) in healthy colon mucosa.ConclusionsOur study suggests that germline genetic variation is associated with the quantity and diversity of adaptive immune responses in CRC. Further studies are warranted to replicate these findings in additional samples and to investigate functional genomic mechanisms.

Interpretation of PD-L1 expression in gastric cancer: summary of a consensus meeting of Korean gastrointestinal pathologists.

Nivolumab plus chemotherapy in the first-line setting has demonstrated clinical efficacy in patients with human epidermal growth factor receptor 2-negative advanced or metastatic gastric cancer, and is currently indicated as a standard treatment. Programmed death-ligand 1 (PD-L1) expression is an important biomarker for predicting response to anti-programmed death 1/PD-L1 agents in several solid tumors, including gastric cancer. In the CheckMate-649 trial, significant clinical improvements were observed in patients with PD-L1 combined positive score (CPS) ≥ 5, determined using the 28-8 pharmDx assay. Accordingly, an accurate interpretation of PD-L1 CPS, especially at a cutoff of 5, is important. The CPS method evaluates both immune and tumor cells and provides a comprehensive assessment of PD-L1 expression in the tumor microenvironment of gastric cancer. However, CPS evaluation has several limitations, one of which is poor interobserver concordance among pathologists. Despite these limitations, clinical indications relying on PD-L1 CPS are increasing. In response, Korean gastrointestinal pathologists held a consensus meeting for the interpretation of PD-L1 CPS in gastric cancer. Eleven pathologists reviewed 20 PD-L1 slides with a CPS cutoff close to 5, stained with the 28-8 pharmDx assay, and determined the consensus scores. The issues observed in discrepant cases were discussed. In this review, we present cases of gastric cancer with consensus PD-L1 CPS. In addition, we briefly touch upon current practices and clinical issues associated with assays used for the assessment of PD-L1 expression in gastric cancer.

Gastric Carcinoma in Autoimmune Gastritis: A Histopathologic and Molecular Study

Patients with autoimmune gastritis (AIG) have a 13-fold risk of developing type-1 neuroendocrine tumors, whereas the risk for gastric adenocarcinoma is still uncertain. Here we describe the clinicopathologic and molecular features of a series of gastric carcinomas (GC) arising in the context of AIG. A total of 26 AIG-associated GC specimens were collected from 4 Italian Institutions. Immunohistochemistry for MUC1, MUC2, MUC5AC, MUC6, CDX2, HER2, PD-L1, CLDN18, mismatch repair (MMR) proteins, and p53 and EBV-encoded RNA (EBER) in situ hybridization were performed. Histologic and immunohistochemical features were jointly reviewed by 5 expert gastrointestinal pathologists. Next-generation sequencing analysis (TrueSight Oncology 500, Illumina) of 523 cancer-related genes was performed on 19 cases. Most tumors were diagnosed as pT1 (52%) and they were located in the corpus/fundus (58%) and associated with operative link for gastritis assessment stage II gastritis (80.8%), absence of parietal cells, complete intestinal metaplasia, and enterochromaffin-like-cell micronodular hyperplasia. Only 4 (15.4%) GCs were diagnosed during follow-up for AIG. The following histotypes were identified: 20 (77%) adenocarcinomas; 3 (11%) mixed neuroendocrine–non-neuroendocrine neoplasms, and 2 (8%) high-grade solid adenocarcinomas with focal neuroendocrine component, 1 (4%) adenocarcinoma with an amphicrine component. Overall, 7 cases (27%) showed MMR deficiency, 3 (12%) were positive (score 3+) for HER2, 6 (23%) were CLDN18 positive, and 11 (42%) had PD-L1 combined positive score ≥ 10. EBER was negative in all cases. Molecular analysis revealed 5/19 (26%) microsatellite instability (MSI) cases and 7 (37%) tumor mutational burden (TMB) high. The most frequently altered genes were TP53 (8/19, 42%), RNF43 (7/19, 37%), ERBB2 (7/19, 37% [2 amplified and 5 mutated cases]), ARID1A (6/19, 32%), and PIK3CA (4/19, 21%). In summary, AIG-associated GCs are often diagnosed at low stage in patients with longstanding misrecognized severe AIG; they often display a neuroendocrine component or differentiation, have relatively higher rates of MMR deficiency, and TMB high.

Histopathologic evaluation of gastric intestinal metaplasia in non-neoplastic biopsy specimens: Accuracy and interobserver reliability among general pathologists and pathology residents

ObjectivesThis study aimed to evaluate the accuracy and interobserver reliability of diagnosing and subtyping gastric intestinal metaplasia (IM) among general pathologists and pathology residents at a university hospital in Thailand, focusing on the challenges in the histopathologic evaluation of gastric IM for less experienced practitioners. MethodsThe study analyzed 44 non-neoplastic gastric biopsies, using a consensus diagnosis of gastrointestinal pathologists as the reference standard. Participants included 6 general pathologists and 9 pathology residents who assessed gastric IM and categorized its subtype (complete, incomplete, or mixed) on digital slides. After initial evaluations and receiving feedback, participants reviewed specific images of gastric IM, as agreed by experts. Following a one-month washout period, a reevaluation of the slides was conducted. ResultsDiagnostic accuracy, interobserver reliability, and time taken for diagnosis improved following training, with general pathologists showing higher accuracies than residents (median accuracy of gastric IM detection: 100 % vs. 97.7 %). Increased years of experience were associated with more IM detection accuracy (p-value<0.05). However, the overall median accuracy for diagnosing incomplete IM remained lower than for complete IM (86.4 % vs. 97.7 %). After training, diagnostic errors occurred in 6 out of 44 specimens (13.6 %), reported by over 40 % of participants. Errors involved omitting 5 slides with incomplete IM and 1 with complete IM, all showing a subtle presence of IM. ConclusionsThe study highlights the diagnostic challenges in identifying incomplete gastric IM, showing notable discrepancies in accuracy and interobserver agreement. It underscores the need for better diagnostic protocols and training to enhance detection and management outcomes.

Incomplete mucosal layer excision during EMR: a potential source of recurrent adenoma (with video)

Background and AimsResidual or recurrent adenoma detected during surveillance (RRA) is the major limitation of endoscopic mucosal resection (EMR). The pathogenesis of RRA is unknown although thermal ablation of the post-EMR defect (PED) margin reduces RRA. We aimed to identify a feature within the PED which could be associated with RRA. MethodsBetween 1/2017 and 7/2020 detailed prospective procedural data on all EMR procedures performed at a single centre were retrospectively analysed. At the completion of EMR the PED was systematically examined for features of incomplete mucosal layer excision (IME). This was defined as a demarcated area within the PED bordered by a white electrocautery ring, containing endoscopically identifiable features suggesting incomplete resection of the mucosa including lacy capillaries and/or visible fibres of the muscularis mucosae. Areas of IME were re-injected and re-excised by snare and submitted separately for blinded specialist gastrointestinal pathologist review. ResultsEMR was performed for 508 large non-pedunculated colorectal polyps (LNPCPs) (median size 35mm). In 10 PED (2.0%) an area of IME was identified and excised. Histopathological examination of areas of suspected IME demonstrated muscularis mucosae in 9/10 (90%), residual lamina propria in 9/10 (90.0%) and residual adenoma in 5/10 (50.0%). No RRA was detected during follow-up after re-excision of IME. ConclusionWe report the novel finding of IME within the PED after EMR of LNPCPs. IME may contain microscopic residual adenoma and therefore is a risk for RRA during follow-up. After completion of EMR the PED should be carefully evaluated and if IME is found it should be excised.

P229 Comparison of Different Histological Scoring Systems for Ulcerative Colitis [Nancy Histological Index, Robarts Histopathology Index and IBD-DCA (Inflammatory Bowel Disease-Distribution, Chronicity, Activity Score)] Among Specialists in GI Pathology and General Pathologists Pre- &amp; Post Workshop

Abstract Background Histopathology is an emerging treatment target and an important parameter in predicting clinical outcomes of patients with ulcerative colitis (UC). Histological scoring indices Nancy Histological Index (NHI) and Robarts Histopathology Index (RHI) have been developed and validated for UC. We aim to compare the inter-observer reliability of NHI, RHI and the recently described Inflammatory Bowel Disease-Distribution, Chronicity, Activity (IBD-DCA) Score among gastrointestinal (GI) pathologists versus general pathologists pre- and post-workshop to determine the scoring system with the best reproducibility. Methods Digital whole slide images of 20 H&amp;E-stained biopsies of ulcerative colitis (UC) cases are scored independently by 6 GI pathologists and 44 general pathologists that attended the Singhealth GI Pathology Course 2023 using NHI, RHI and IBD-DCA on the digital Pathpresenter platform. The 44 course participants performed the scoring before the course and again after attending a 3-hour IBD workshop on the assessment of histological remission using these 3 scoring systems. Data tabulation using “Free Online Surveys” platform is collated and intraclass correlation coefficient (ICC) of each component of the scoring indices is calculated. The ICC values of &amp;lt;0.5, 0.5–0.75, 0.75–0.9, and &amp;gt;0.9, indicate ‘poor’, ‘moderate’, ‘good’, and ‘excellent’ agreement, respectively. Results There is good inter-observer reliability for IBD-DCA ‘Activity’ component (ICC 0.85) and NHI (ICC 0.83) among GI pathologists while lBD-DCA ‘Distribution’ component (ICC 0.395) has the poorest agreement. Poor to moderate inter-observer reliability for all 3 scoring systems (ICC 0.4 – 0.6) is seen among the 44 participants pre-workshop with an observed post-workshop improvement, achieving best agreement for the NHI, ‘lamina propria neutrophils’ component of RHI and IBD-DCA ‘activity’ component (ICC 0.7). Conclusion GI pathologists are generally consistent in assessing disease activity in UC with good inter-observer reliability for NHI (a scoring system with an emphasis on activity grade) and only the ‘activity’ component of the IBD-DCA. Our study confirms NHI as a reliable scoring system for UC with the best reproducibility and favour its application to assess histological response in routine clinical practice to help gastroenterologists better manage patients with UC. We have also demonstrated that improvement in NHI scoring reproducibility can be achieved after training workshop for pathologists less familiar with the application of IBD histological scoring.

DOP35 Spatial transcriptomics reveals cellular niches associated with histological inflammation in postoperative Crohn’s Disease

Abstract Background Postoperative Crohn’s disease (CD) recurs in ~70% of patients ≤1 year following ileocolonic resection (ICR), as observed endoscopically. Current understanding of molecular determinants underlying histological intestinal inflammation in patients with postoperative CD recurrence is minimal. To address this issue, we used advanced spatial transcriptomic analyses on intestinal biopsy samples with matched histological and endoscopic assessments from neoterminal ileum, anastomosis, and colon of patients with CD who had undergone colonoscopy following ICR. Methods Formalin-fixed paraffin-embedded (FFPE) tissue biopsies from neoterminal ileum, anastomosis, and colon were prospectively collected from a 15-patient cross-sectional cohort with CD who underwent routine endoscopic assessment following ICR. Spatial transcriptomics was performed on samples using 10X Genomics Visium CytAssist Spatial Gene Expression for FFPE V2.0. Annotation of tissue regions of histologically active inflammation and classification of histologically inactive (Robarts Histopathology Index ≤3 with subscores of 0 for neutrophils in the lamina propria and epithelium) or active disease were performed by an expert gastrointestinal pathologist. R programming language was used for data analysis (Figure). Results Fourteen of the 43 (32.6%) FFPE biopsies had histological evidence of inflammation. Spatial transcriptomics clustering revealed a distinct transcriptional signature by the segregation of 4 clusters ("inflamed clusters") composed mostly (≥69%) of cells from samples defined by histologically active disease. Tissue regions identified as inflamed by expert pathologist annotation contributed to &amp;gt;46% of inflamed clusters’ composition and &amp;lt;15% of remaining clusters. Cell type decomposition and cellular niche analysis revealed immune (e.g., myeloid, T cells, and B cells) and epithelial cells in close proximity sharing a similar microenvironment in 3 inflamed clusters while the 4th cluster was composed of &amp;gt;90% epithelial cells. Differentially expressed genes from the inflamed clusters were similarly expressed across intestinal segments including inflamed anastomotic biopsies and were enriched for signalling pathways involving immune cells recruitment/activation, inflammatory signalling, extracellular matrix organisation, and oxidative stress response. Conclusion This is the first study to explore spatial transcriptomic signatures associated with histological inflammation in patients with postoperative CD recurrence. Our analysis revealed a spatial signature of cellular niches and signalling pathways arising upon histological inflammation, providing insight into therapeutic targets and biomarkers across anatomic locations and the anastomosis.

P013 Magnetic Resonance Imaging-Based Average T2 Signal as A Non-Invasive Measure of Fibrosis In Enteric Crohn’s Disease

Abstract Background In Crohn’s Disease (CD), 10% of patients present with fibrostenosis with a further 10% progressing from inflammatory to a fibrostenotic disease behaviour over 7 years. 40% of fibrostenotic CD patients need surgery at 5 years compared to ~10% with inflammatory disease. Present non-invasive fibrosis biomarkers lack the required accuracy needed to be used routinely for clinical decision making. T1, T2, diffusion weighted imaging, motility and bowel volumes have shown promise in the non-invasive measure of fibrosis. Methods The primary objective of this study is to undertake biological validation of MRI measures as independent imaging biomarkers of histological fibrosis with the primary outcome being the correlation between MRI measures and histological fibrosis measures. GI-Seg (Motilent, London, UK) is an image analysis tool used to segment the gastrointestinal tract on T2W MRI scans. Patients with CD histological diagnosis and in need of surgical resection for stenosis attended a one-hour 3T MRI scanning session within 12 weeks prior to their intestinal resection surgery. Histological samples were scored by a specialized gastrointestinal pathologist for inflammation, fibrosis, and muscular hypertrophy. An expert radiologist with the help of the histopathologist located the strictures on DWI, quantitative T2&amp;T2 scans, and T2 weighted clinical MRI scans. GI-Seg was used to generate a 3D model of the stricture on T2W scans measuring bowel wall volume and average signal intensity of each stricture. Pearson correlation coefficient was used to quantify the correlation between the variables. Results A total of 10 CD patients, encompassing 20 strictures, were included in the study. The analysis revealed that the average T2 signal has a significant correlation with global fibrosis scores (r(20) = .563, p = .010) (Figure) and total inflammation scores (r(20) = .451, p = .046). Additionally, stricture volume showed a fair correlation with chronic inflammation component scores (r(20) = .453, p = .045). Notably, quantitative T1 values correlated with total inflammation scores (r(17) = .493, p = .045). Conclusion The study reveals fair correlations between the T2 signal average and both global fibrosis and global inflammation scores, as well as between stricture volume and chronic inflammation in CD strictures. While these findings indicate that the GI-seg tool's measurements of bowel wall volume and signal intensity have potential utility as imaging biomarkers for fibrosis and inflammation, the results also underscore the necessity for additional markers that are specifically correlated with fibrosis. Such markers are essential to distinctly identify fibrotic changes, independent of inflammatory processes.

P342 Role of the Number and Location of Endoscopic Biopsies on the Detection of Granuloma in Patients with Isolated Intestinal Tuberculosis

Abstract Background Detecting granulomas is valuable for the diagnosis of isolated intestinal tuberculosis (ITB). However, how to perform an effective endoscopic biopsy remains unclear. We aimed to explore the impact of the number and location of endoscopic biopsies on granuloma detection in patients with isolated ITB. Methods A prospective analysis was conducted in 50 patients with confirmed isolated ITB who underwent predetermined endoscopic biopsy and pathological tests. 50 patients with isolated ITB were included for analysis. The diagnosis was confirmed based on microbiological, endoscopic, and histopathological evidences. For each patient, eight endoscopic biopsy specimens were obtained from either ulcer bases (n=4) or ulcer margins (n=4). After fixation, the specimens were serially sectioned into 8 slices on average. The slices were then stained and examined by an experienced gastrointestinal pathologist who were blinded to the patient information. Results The detection rates of granulomas from 2, 4, 6, and 8 biopsy specimens were 10, 28, 50, and 82%, respectively (5/50 vs 14/50 vs 25/50 vs 41/50, P&amp;lt;0.00001). When 4 biopsy specimens were used, the granuloma detection rate with specimens from the ulcer base was significantly higher than that from the ulcer margin (41/50 vs 14/50, P&amp;lt;0.0001). 34% (17/50) of the patients had necrotising-confluent granuloma, and 12% (6/50) had confluent (&amp;gt;400 um) granuloma. In total, 205 granulomas were identified in 41 patients. Multi-granulomas were detected on 49 slices while mono-granulomas on were detected on 72 slices. 62.9% (129/205) of granulomas were detected in the ulcer base, 27.8% (57/205) in the lamina propria, and 9.3% (19/205) in the submucosa. Conclusion Using more than 8 or 4 biopsy specimens from the ulcer base improved the detection rate (over 50%) of necrotising or confluent granulomas for ITB. To improve the accuracy of diagnosis, clinicians should obtain ≥4 pieces of endoscopic biopsy from the ulcer base and conduct a deep biopsy into the lamina propria. Nevertheless, the integration of clinical characteristics and anti-TB responses is still required for suspected patients with undetected granulomas.