Clinical and Pathologic Response to Neoadjuvant Immunotherapy in DNA Mismatch Repair Protein-Deficient Gastroesophageal Cancers.

BACKGROUND: Mismatch repair deficient (dMMR) gastroesophageal cancers (GEC) are a distinct subgroup. Among patients with locally advanced disease, previous trial data suggest a good response to neoadjuvant immune checkpoint inhibitors (nICI). PATIENTS AND METHODS: Since 2019, our institution has routinely performed MMR testing for new GEC cases. Patients diagnosed with GEC (2019-2024) were included in the study. Quantitative data are described as the median and interquartile range (IQR); qualitative data are described as quantities and percentages. RESULTS: A total of 24 patients with dMMR GEC were identified following implementation of routine immunohistochemical testing; 14 were potentially resectable with a median follow-up of 14 months (IQR 8-27). All patients underwent pre-treatment positron emission tomography (PET; median SUV 20.9). Among the 14 potentially resectable patients, 4 underwent immediate surgery, 10 were treated with nICI, and 5 underwent surgical resection to date. All regimens included PD-1 inhibitors, with 70% receiving pembrolizumab. Re-staging PET was performed in five patients; the median post-nICI SUV was 5.1 (range 4.7-6.3). All resected specimens had gross ulceration after nICI, but 60% (N = 3) had a pathologic complete response (pCR) following nICI; one patient had a near-complete response (nCR) and one patient had a partial response (pPR). Reduction in SUV was 75% and 82% in the pCR patients, 25% in the nCR patient, and 43% in the pPR patient. CONCLUSIONS: dMMR GECs are responsive to nICI in this limited experience, mirroring early clinical trial data. Given persistent metabolic activity and visible ulceration despite pCR, studies should continue to optimize tools for estimating post-nICI pCR in these patients.

Fundic Gland Polyps Lack DNA Content Abnormality Characteristic of Other Adenomatous Precursor Lesions in the Gastrointestinal Tract.

Fundic gland polyps (FGPs) develop sporadically (frequently after proton pump inhibitor therapy) or in the setting of a hereditary polyposis syndrome, such as familial adenomatous polyposis (FAP). FAP-related FGPs often demonstrate low-grade dysplasia (LGD) and are frequently associated with APC mutations, even in the absence of dysplasia. Sporadic FGPs with dysplasia are molecularly similar to FAP-related FGPs and demonstrate frequent mutations in APC gene. Despite having similar molecular alterations with colorectal and other adenomatous precursor lesions in the gastrointestinal (GI) tract, FGPs rarely progress to advanced gastric neoplasia (high-grade dysplasia [HGD] or adenocarcinoma), and their role in gastric tumorigenesis remains unclear but likely limited. The clinicopathologic features of 192 patients diagnosed with FGPs, including 86 with FAP-related FGPs (33 with dysplastic FGPs and 53 with nondysplastic FGPs) and 106 with sporadic FGPs (12 with dysplastic FGPs and 94 with nondysplastic FGPs), were analyzed. DNA flow cytometry was performed on 111 FAP-related FGP biopsies, including 32 FGPs with LGD and 79 nondysplastic FGPs, to assess the presence of abnormal DNA content (ie, aneuploidy or elevated 4N fraction). Moreover, 40 sporadic FGP biopsies, including 14 dysplastic (13 LGD and 1 HGD) and 26 nondysplastic FGPs, were examined for DNA content abnormality. Patients with FAP and nondysplastic FGPs were more likely to be younger (mean age, 32 years) and present with multiple FGPs (92%, defined as having ≥2 FGPs) than those with sporadic nondysplastic FGPs (61 years and 65%, respectively; P < .001). They also recorded higher rates of previous or concurrent gastric epithelial dysplasia not occurring in a FGP (8%, P = .016), nongastric GI dysplasia (96%, P < .001), and nongastric GI malignancy (17%, P = .001) compared with those with sporadic nondysplastic FGPs (0%, 52%, and 2%, respectively). The sporadic group was more frequently associated with proton pump inhibitor therapy (78%, P < .001), gastric intestinal metaplasia (24%, P = .004), and a family history of gastric cancer (10%, P = .027) than the FAP group (19%, 6%, and 0%, respectively). Almost all FAP-related FGPs had a polypoid endoscopic appearance (98% vs 84% for sporadic FGPs; P = .009). The mean size of the largest FAP-related FGPs (0.5 cm) was similar to that of sporadic FGPs (0.7 cm) (P = .069). None of the 147 patients with FAP-related or sporadic nondysplastic FGPs were associated with subsequent detection of advanced gastric neoplasia within a mean follow-up time of 54 months (range, <1 to 277 months). However, 2 (4%) of the 45 patients with FAP-related or sporadic dysplastic FGPs developed advanced gastric neoplasia within a mean follow-up time of 59 months (range, <1 to 236 months). One (3%) of the 33 patients with FAP and dysplastic FGPs developed signet ring cell adenocarcinoma, whereas 1 (8%) of the 12 patients with sporadic dysplastic FGPs developed HGD (P = .445). However, none of the FAP-related and sporadic FGP biopsies, regardless of the presence or absence of dysplasia, demonstrated DNA content abnormality. In conclusion, FGPs lack large-scale chromosomal changes that are characteristic of the typical adenoma-carcinoma sequence involved in the development of other GI malignancies. Progression to advanced gastric neoplasia is rare in FGPs, which may be partly explained by the apparent lack of the chromosomal instability phenotype in these lesions.

Tumor Regression Grade and Overall Survival following Gastrectomy with Preoperative Therapy for Gastric Cancer.

BACKGROUND: Pre-/perioperative chemotherapy is well-established for management of locoregional gastric cancer (LRGC). The American Joint Committee on Cancer advocates histopathologic assessment of tumor regression grade (TRG) but does not endorse a specific schema. We sought to examine the prognostic value of the recently revised National Comprehensive Cancer Network (NCCN) definition of TRG specifying TRG0 as no disease in primary tumor or lymph nodes. PATIENTS AND METHODS: Patients with clinical-stage T2+/N+/M0 LRGC receiving preoperative chemotherapy and curative-intent gastrectomy were identified (2000-2020). TRG using the current NCCN definition was retrospectively assigned. Factors associated with TRG were examined using ordinal logistic regression and overall survival (OS) was assessed using the Kaplan-Meier method and Cox regression. RESULTS: Among 117 patients, the most common chemotherapy regimen was epirubicin, cisplatin, plus fluorouracil or capecitabine (ECF/ECX) (n = 48, 41%), followed by folinic acid, fluorouracil, and oxaliplatin (FOLFOX) (n = 30, 26%), and fluorouracil, leucovorin, oxaliplatin, plus docetaxel (FLOT) (n = 13, 11%). TRG3 was the most common histopathologic response (n = 68, 58%), followed by TRG2 (n = 25, 21%), TRG1 (n = 18, 15%), and, lastly, TRG0 (n = 6, 5.1%). The only preoperative factor independently associated with lower TRG was gastroesophageal junction tumor location (OR 0.24, p = 0.012). Higher TRG was independently associated with worse OS in a stepwise fashion (HR 1.49, p = 0.026). Posttreatment pathologic lymph node status was the strongest prognostic factor (HR 1.93, p = 0.026). Independent prognostic value of TRG and ypT stage could not be shown due to substantial overlap. CONCLUSIONS: TRG using the contemporary NCCN definition is associated with OS in LRGC. TRG0 is uncommon but with excellent prognosis. ypN status is the strongest prognostic factor and the revised NCCN definition acknowledging this is appropriate.

DNA content abnormality frequently develops in the right/proximal colon in patients with primary sclerosing cholangitis and inflammatory bowel disease and is highly predictive of subsequent detection of dysplasia.

AIMS: Patients with primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD, termed PSC-IBD) have a higher risk of harbouring nonconventional and/or invisible dysplasias, especially in the right/proximal colon, than those with IBD alone. We postulated that DNA content abnormality may be frequently detected in the right/proximal colon in PSC-IBD patients, even in the absence of dysplasia, and that this may predispose to progression to nonconventional and/or invisible dysplasias that are often associated with increased rates of aneuploidy and advanced neoplasia. METHODS AND RESULTS: DNA flow cytometry was performed on 96 morphologically benign colon biopsies taken throughout the colon from 25 PSC-IBD patients during the surveillance colonoscopy that preceded the next procedure that detected dysplasia. Thirty (31%) of the 96 benign colon biopsies in this dysplasia group demonstrated abnormal DNA content, with a propensity for the right/proximal colon (70%) (P < 0.001). In contrast, only one (1%) of 87 benign colon biopsies from 20 IBD patients without neoplasia (control group) demonstrated DNA content abnormality, and it was from the left colon. For analysis per patient, 48% (12 of 25) of the patients in the dysplasia group had abnormal DNA content compared with 5% (1 of 20) of the control group (P = 0.002). Of the 12 PSC-IBD patients with DNA content abnormality, invisible dysplasia was detected in 10 (83%) patients on follow-up, nine (75%) of whom had nonconventional dysplasia. CONCLUSION: PSC-IBD patients have an increased risk of developing abnormal DNA content in the right/proximal colon, predating the detection of dysplasia.

Non-conventional dysplasia is frequently associated with low-grade tubuloglandular and mucinous adenocarcinomas in inflammatory bowel disease.

There is limited information regarding the clinicopathological features of low-grade tubuloglandular (LGTGA) and mucinous (MAC) adenocarcinomas occurring in inflammatory bowel disease (IBD), especially with regard to their precursor lesions. METHODS AND RESULTS: Forty-six IBD colectomy specimens with LGTGA (n = 17) or MAC (n = 29) with adjacent precursor lesions were analysed. As controls, 12 IBD colectomy specimens with well- to moderately differentiated adenocarcinoma that lacked any mucinous, signet ring cell, low-grade tubuloglandular or serrated features were also analysed. Compared with MACs and controls, LGTGAs more often had a flat/invisible macroscopic appearance (LGTGAs = 88%, MACs = 34%, controls = 25%, P < 0.001). MACs were more likely to have high-grade differentiation (MACs = 31%, LGTGAs = 0%, controls = 0%, P = 0.002) and a higher pathological stage (pT3 and pT4 MACs = 76%, LGTGAs = 35%, controls = 33%, P = 0.007) than LGTGAs and controls. LGTGAs (70%) and MACs (53%) were more frequently associated with non-conventional dysplasia than controls (0%) (P < 0.001). Crypt cell (40%) and hypermucinous (34%) dysplasias were the most common non-conventional subtypes associated with LGTGAs and MACs, respectively. Synchronous dysplasia often demonstrated non-conventional features in the LGTGA (33%) and MAC (47%) groups (versus 0% for the control group, P = 0.074). Synchronous cancer frequently showed similar histological features as the main tumour (LGTGA group = 60%, MAC group = 38%, control group = 100%). CONCLUSIONS: Crypt cell and hypermucinous dysplasias are the most common precursor lesions associated with LGTGAs and MACs, respectively, and may serve as a marker of increased risk for these cancer subtypes.

Primary plasmablastic lymphoma of the gastrointestinal tract: A series of 13 HIV-negative cases and a review of literature.

CONTEXT: Primary gastrointestinal plasmablastic lymphoma (GI-PBL) is a rare variant of diffuse B-cell lymphoma with an aggressive clinical course. PBL was initially reported among HIV-positive patients; however, subsequent studies have shown that it also occurs among HIV-negative patients. Its clinical characteristics remain poorly understood. This study aims to retrospectively analyze the clinicopathological findings of primary GI-PBLs in HIV-negative patients. DESIGN: Primary HIV-negative GI-PBL cases from 2008 to 2022 were reviewed. Clinicopathologic features and outcomes were analyzed. RESULTS: The cohort of 13 patients had a male-to-female ratio of 9:1 (3 patients' genders not available), with an average age of 61 (range, 30-92) years. The most involved location was the colon (n = 7 [53.8 %]), followed by the small bowel (n = 3 [23.1 %]), stomach (n = 2 [15.4 %]), rectum (n = 1 [7.7 %]), and anus (n = 1 [7.7 %]). Most patients (n = 10 [77 %]) showed isolated GI tract involvement. Eight patients had chronic inflammatory and/or immunocompromised status, including 4 with inflammatory bowel disease (all of whom underwent treatment), 3 with post-organ transplant status, and 1 with irritable bowel syndrome. All cases exhibited cytokeratin-/CD20-/PAX-5-/CD138+ and/or MUM1+ immunophenotype. Based on available data, 8 of 11 (72.7 %) patients had Epstein-Barr virus reactivation. Among 11 patients with follow-up data, the mean follow-up duration was 13.5 (range, 3-40) months; at the end of follow-up, 45.5 % of patients (5 of 11 patients) showed complete remission after chemotherapy. CONCLUSION: Primary HIV-negative GI-PBL occurs predominantly in the colon of relatively elderly males with immunosuppression. Its clinical course can be heterogenous, presenting a comorbidity with inflammatory bowel disease or post-organ transplantation status.

[Conventional and non-conventional dysplasia in patients with inflammatory bowel disease]. / Dysplasies conventionnelles et non conventionnelles compliquant les maladies inflammatoires chroniques de l'intestin.

Compared to the general population, patients with inflammatory bowel disease (IBD), both ulcerative colitis (UC) or Crohn's disease (CD), are at increased risk of developing some cancers, particularly colorectal cancers (CRC). CRCs, the vast majority of which are adenocarcinomas, develop from a precancerous lesion called dysplasia (or intraepithelial neoplasia) via an inflammation-dysplasia-adenocarcinoma sequence. The advancements of new endoscopic techniques, including visualisation and resection techniques, has led to a reclassification of dysplasia lesions into visible and invisible lesions and their therapeutic management, with a more conservative approach to the colorectal setting. In addition, besides conventional dysplasia, of intestinal phenotype, classically described in IBD, non-conventional dysplasias (as opposed to conventional dysplasia of intestinal phenotype) are now described, including at least seven subtypes. Recognition of these unconventional subtypes, which are still poorly known from pathologists, is becoming crucial, as some of these subtypes appear to be at high risk of developing advanced neoplasia (i.e. high-grade dysplasia or CRC). This review briefly describes the macroscopic features of dysplastic lesions in IBD, as well as their therapeutic management, followed by the clinicopathological features of these dysplastic lesions, with particular emphasis on the new subtypes of unconventional dysplasia, both from a morphological and molecular point of view.

An International Consensus to Standardize Integration of Histopathology in Ulcerative Colitis Clinical Trials.

BACKGROUND & AIMS: Histopathology is an emerging treatment target in ulcerative colitis (UC) clinical trials. Our aim was to provide guidance on standardizing biopsy collection protocols, identifying optimal evaluative indices, and defining thresholds for histologic response and remission after treatment. METHODS: An international, interdisciplinary expert panel of 19 gastroenterologists and gastrointestinal pathologists was assembled. A modified RAND/University of California, Los Angeles appropriateness methodology was used to address relevant issues. A total of 138 statements were derived from a systematic review of the literature and expert opinion. Each statement was anonymously rated as appropriate, uncertain, or inappropriate using a 9-point scale. Survey results were reviewed and discussed before a second round of voting. RESULTS: Histologic measurements collected using a uniform biopsy strategy are important for assessing disease activity and determining therapeutic efficacy in UC clinical trials. Multiple biopsy strategies were deemed acceptable, including segmental biopsies collected according to the endoscopic appearance. Biopsies should be scored for architectural change, lamina propria chronic inflammation, basal plasmacytosis, lamina propria and epithelial neutrophils, epithelial damage, and erosions/ulcerations. The Geboes score, Robarts Histopathology Index, and Nancy Index were considered appropriate for assessing histologic activity; use of the modified Riley score and Harpaz Index were uncertain. Histologic activity at baseline should be required for enrollment, recognizing this carries operational implications. Achievement of histologic improvement or remission was considered an appropriate and realistic therapeutic target. Current histologic indices require validation for pediatric populations. CONCLUSIONS: These recommendations provide a framework for standardized implementation of histopathology in UC trials. Additional work is required to address operational considerations and areas of uncertainty.

Utility of ancillary studies in the diagnosis and risk assessment of Barrett's esophagus and dysplasia.

Barrett's esophagus (BE) is a major risk factor for the development of esophageal adenocarcinoma (EAC). BE patients undergo periodic endoscopic surveillance with biopsies to detect dysplasia and EAC, but this strategy is imperfect owing to sampling error and inconsistencies in the diagnosis and grading of dysplasia, which may result in an inaccurate diagnosis or risk assessment for progression to EAC. The desire for more accurate diagnosis and better risk stratification has prompted the investigation and development of potential biomarkers that might assist pathologists and clinicians in the management of BE patients, allowing more aggressive endoscopic surveillance and treatment options to be targeted to high-risk individuals, while avoiding frequent surveillance or unnecessary interventions in those at lower risk. It is known that progression of BE to dysplasia and EAC is accompanied by a host of genetic alterations, and that exploration of these markers could be potentially useful to diagnose/grade dysplasia and/or to risk stratify BE patients. Several biomarkers have shown promise in identifying early neoplastic transformation and thus may be useful adjuncts to histologic evaluation. This review provides an overview of some of the currently available biomarkers and assays, including p53 immunostaining, Wide Area Transepithelial Sampling with Three-Dimensional Computer-Assisted Analysis (WATS3D), TissueCypher, mutational load analysis (BarreGen), fluorescence in situ hybridization, and DNA content abnormalities as detected by DNA flow cytometry.

Integrating a Disease-Focused Tumor Board as a Delivery-of-Care Model to Expedite Treatment Initiation for Patients With Liver Malignancies.

BACKGROUND: Patients with hepatobiliary malignancies are especially vulnerable to treatment delays. This study sought to evaluate the impact of implementing a new delivery-of-care model centered around a hepatobiliary multidisciplinary tumor board (HB-MTB) and integrated with an optimized patient workflow process to expedite treatment initiation. METHODS: A hybrid type 2 study (effectiveness-implementation) was performed. Implementation measures were examined prospectively using the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) approach during 5 years after the HB-MTB program deployment (2015-2020). The primary outcome was effectiveness, measured as time to treatment initiation (TTI) using a before and after design (1 year each). The patients were grouped into before (BP) and after (AP) categories based on date of HB-MTB program implementation. Multivariable Cox and linear regression analyses were performed to examine and compare time to treatment initiation between groups. RESULTS: The HB-MTB program enrolled 2457 patients (reach). The RE-AIM measures were favorable and improved over time (P < 0.01 for all). The median TTI was lower for the AP group than for the BP group (17 vs 24 days; P < 0.01). In the multivariable Cox and linear regressions, treatment in the AP group was associated with a faster TTI (hazard ratio, 1.75; 95 % confidence interval, 1.31-2.35; p < 0.01), and a mean of 13 days faster treatment initiation than the BP group (P < 0.01). CONCLUSIONS: Implementation of an HB-MTB program integrated with an optimized patient workflow was successful and led to faster treatment initiation. This delivery-of-care model can serve as a blueprint to expedite treatment of patients with cancer.

Clinicopathologic features of undetected dysplasia found in total colectomy or proctocolectomy specimens of patients with inflammatory bowel disease.

AIMS: It remains controversial as to whether targeted biopsies should completely replace random biopsies for dysplasia surveillance in patients with inflammatory bowel disease (IBD). Several histologic patterns of nonconventional dysplasia have been described in IBD. This study aimed to investigate the rate and clinicopathologic features of dysplastic lesions found in total colectomy or proctocolectomy specimens that were undetected on prior colonoscopy. METHODS AND RESULTS: The study analyzed 207 consecutive IBD patients who underwent a total colectomy or proctocolectomy and had at least one high-definition colonoscopy prior to colectomy. Dysplasia found in the colectomy specimens was classified as undetected, only when there was no corresponding site of dysplasia detected on previous colonoscopic biopsies. Twenty-seven (13%) patients had 49 undetected dysplastic lesions found only at colectomy, while 22 (11%) had 31 previously detected dysplastic lesions only. The remaining 158 (76%) patients had no dysplasia. A greater proportion of the undetected (19%) or previously detected (23%) dysplasia group had concurrent primary sclerosing cholangitis compared with only 3% in the group without dysplasia (P < 0.001). The undetected dysplastic lesions were more likely to have nonconventional dysplastic features (76%), low-grade dysplasia (94%), and a flat/invisible gross appearance (73%) compared with the previously detected dysplastic lesions (13%, 68%, and 48%, respectively) (P < 0.05). Almost all patients with undetected dysplasia (93%) had a colonoscopy within 1 year of colectomy. CONCLUSION: The rate of undetected dysplasia is not insignificant (13%), suggesting that increased random biopsies may improve the rate of dysplasia detection, including nonconventional dysplasia.

Increased histologic inflammation is an independent risk factor for nonconventional dysplasia in ulcerative colitis.

AIMS: Several types of nonconventional dysplasia have been described in inflammatory bowel disease. Hypermucinous, goblet cell-deficient, and crypt cell dysplasias are considered high-risk subtypes, as they often have molecular features of advanced neoplasia (e.g. aneuploidy) and are more frequently associated with advanced neoplasia than conventional dysplasia. This study investigated if increased colonic inflammation is a risk factor for nonconventional dysplasia. METHODS AND RESULTS: A cohort of 125 patients with ulcerative colitis (UC)-associated dysplasia were analyzed and compared with 50 control UC patients without a history of neoplasia. For each patient, all biopsies prior to the initial detection of dysplasia were scored using a 4-point inflammatory activity score. Both mean and maximum scores from all biopsies taken during each colonoscopy were derived. Inflammation burden was calculated by multiplying the average maximum score between each pair of surveillance episodes by length of surveillance interval in years. The average scores of all colonoscopies were used to calculate overall mean, maximum, and inflammation burden scores. In multivariate analyses, higher maximum (odds ratio [OR] 3.4) and inflammation burden (OR 4.2) scores were significantly associated with the detection of dysplasia (P < 0.05). Similarly, higher mean and maximum scores increased the odds of nonconventional dysplasia by 2.7 and 4.9, respectively (P < 0.05). There was a stronger association between these two scores and high-risk subtypes (ORs 4.0 and 7.5, respectively, P < 0.05). CONCLUSION: The risk of nonconventional dysplasia is significantly associated with increased colonic inflammation, which may contribute to its higher rates of aneuploidy and malignancy.

Fundic gland polyps related to diverse aetiologies show subtle morphological differences: a multicentre retrospective study.

AIMS: Fundic gland polyps (FGPs) comprise 66% of all gastric polyps. Although they are usually non-syndromic, they may be associated with various syndromes, including familial adenomatous polyposis (FAP) or gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS). We aimed to evaluate how histological features relate to distinct FGP subtypes. METHODS AND RESULTS: We performed a retrospective analysis of 118 FGPs from 109 patients for the architecture of fundic glands, microcyst lining, parietal cell hyperplasia and surface foveolar epithelial changes. Age, gender and history of FAP or GAPPS were collected. Based on combinations of histological features, three distinct patterns (A, B and C) of FGPs were delineated and correlated to the aetiologies. Non-syndromic FGPs were well-formed polyps composed of disordered fundic glands with intermediate-sized microcysts typically lined by a mixture of oxyntic and mucin-secreting cells (73%). Parietal cell hyperplasia (80%) and foveolar surface hyperplasia (78%) were common. FAP-associated cases demonstrated small microcysts that were predominantly lined by fundic epithelium (77%), with limited parietal cell hyperplasia (27%); foveolar hyperplasia was uncommon. GAPPS-related polyps were the largest, with prominent, mucin-secreting epithelium-lined microcysts (73%). Hyperproliferative aberrant pits were universally present, whereas parietal cell hyperplasia was uncommon. Pattern A was identified in most non-syndromic FGPs (74%) and in a minority of FAP-related FGPs (26%). The majority (82%) of FAP-related FGPs showed pattern B, but only 18% of non-syndromic FGPs did. Pattern C consisted exclusively of GAPPS-associated polyps. CONCLUSIONS: We conclude that, although FGPs share similar histomorphology, subtle differences exist between polyps of different aetiology. In the appropriate clinical setting, the recognition of these variations may help to consider syndromic aetiologies.

Measuring Histologic Activity in Inflammatory Bowel Disease: Why and How.

Histology is used to confirm the diagnosis of inflammatory bowel disease, exclude superimposed infections, and to evaluate for dysplasia. Histology has rarely been used to measure disease activity and guide therapy despite evidence that histologic measurements have value in predicting important clinical outcomes. More recently, there have been numerous studies supporting a role for histologic disease activity measurements in predicting a variety of outcomes including relapse, hospitalizations, steroid use, and dysplasia. The histologic assessment was superior to endoscopic measurements in many of these studies. This review will summarize the recent literature regarding histologic disease activity measurements in ulcerative colitis and Crohn disease. A detailed description of histologic scoring systems will also be provided to provide pathologists with the necessary tools to accurately measure disease activity.

Histologic Diagnosis of Inflammatory Bowel Diseases.

Inflammatory bowel disease, including ulcerative colitis and Crohn disease, is an idiopathic chronic inflammatory condition of the gastrointestinal tract. Since neither the clinical manifestations nor the morphologic features of inflammatory bowel disease are pathognomonic alone, the differential diagnosis to consider is relatively broad, and it relies on the synthesis of clinical, endoscopic, and microscopic features. Long-held histologic diagnostic principles include recognizing structural and inflammatory features of chronicity, that is, architectural distortion, basal plasmacytosis, and expansion of the lamina propria lymphoplasmacytic infiltrate. In addition, evaluation of the neutrophilic inflammation and related crypt and epithelial destruction is essential to gauge the activity of the disease. Nevertheless, these features can be difficult to confirm in special settings, including at the inception of the disease or in partially treated cases. This review will explore the classic morphologic features of ulcerative colitis and Crohn disease, followed by a detailed discussion of atypical and diagnostically challenging presentations and a brief review of the clinical aspects necessary for the daily practice of pathologists.

The Significance of Flat/Invisible Dysplasia and Nonconventional Dysplastic Subtypes in Inflammatory Bowel Disease: A Review of Their Morphologic, Clinicopathologic, and Molecular Characteristics.

Patients with inflammatory bowel disease are at significantly increased risk of dysplasia and colorectal cancer (CRC). The early detection, histologic grading, and removal of dysplasia plays a critical role in preventing the development of CRC. With advances in endoscopic visualization and resection techniques, colectomy is no longer recommended to manage dysplasia, unless surveillance colonoscopy detects flat/invisible dysplasia (either high-grade dysplasia or multifocal low-grade dysplasia) or an endoscopically unresectable lesion. Although there are numerous review articles and book chapters on the morphologic criteria of conventional (intestinal type) dysplasia, the most well-recognized form of dysplasia, at least 7 distinct nonconventional morphologic patterns of epithelial dysplasia have been recently described in inflammatory bowel disease. Most practicing pathologists are not familiar with these nonconventional subtypes and thus, may even overlook some of these dysplastic lesions as benign or reactive. However, the recognition of these subtypes is important, as some of them appear to have a high risk of developing advanced neoplasia (high-grade dysplasia or CRC) and often show molecular alterations characteristic of advanced neoplasia. This review briefly describes the morphologic criteria of conventional dysplasia but predominantly focuses on all 7 nonconventional subtypes as well as our understanding of their clinicopathologic and molecular features that can assist in their risk stratification.

The effect of histologic grade on neoadjuvant treatment outcomes in esophageal cancer.

BACKGROUND AND OBJECTIVES: The gold standard for locoregional esophageal cancer (LEC) treatment includes preoperative chemoradiation and surgical resection, with possible perioperative or adjuvant systemic therapy. With few data associating histologic grade and prognosis in LEC patients receiving neoadjuvant chemoradiation followed by resection, we seek to evaluate this association. METHODS: Our institutional esophagectomy database between 1999 and 2019 was queried, selecting esophageal adenocarcinoma patients who completed neoadjuvant therapy (NAT), followed by esophagectomy. Propensity-score matching of low- and high-histologic grade groups was performed to assess survival metrics using initial clinical grade (cG) and final pathologic grade (pG). We performed a multivariable logistic regression to study predictors of pathologic complete response as a secondary objective. RESULTS: A total of 518 patients met the inclusion criteria. Kaplan-Meier analysis of the matched dataset showed no difference in initial or 5-year recurrence-free survival or overall survival (OS) between cG1 and cG2 versus cG3 based on original grade. When matched according to pG, cG1-2 had improved median survival parameters compared to cG3, with 5-year OS for cG1-2 of 45% versus 27% (p = 0.001). Higher pG, pathologic N stage, and poor response to NAT are predictors of poor survival. CONCLUSION: Patients with post-NAT pG1-2 demonstrated improved survival. Integrating histologic grade into postneoadjuvant staging may be warranted.

Malignant colon polyps: predicting lymph node metastasis following endoscopic excision.

AIM: The risk of lymph node metastasis (LNM) of malignant colon polyps (MCPs) is partly estimated by histologic features of the sampled polyp. However, the routinely available histologic data is limited to tumor grade and status of lymphovascular invasion (LVI). METHODS: The NCDB for colon cancer 2004-2018 was utilized. Patients with pT1Nx adenocarcinoma arising in a polyp and undergoing partial colectomy with ≥ 12 retrieved nodes were selected. NCDB 2004-2017 was used as a training cohort to develop two scoring systems based on a multivariable regression for predictors of LNM including clinical characteristics, grade, and LVI: a nomogram scoring system (NSS) and a simplified scoring system (SSS). These models were internally validated using NCDB 2018 to calculate precision metrics for each model. RESULTS: Six thousand sixty-nine patients were selected in the training cohort. 64.5% of MCPs were in the sigmoid, and LNM rate was 11.2%. Multivariable regression identified younger age, females, hindgut location, higher grade, and LVI as significant predictors of LNM. LNM risk was 1.2% when all unfavorable predictors were absent and exceeded 10% when NSS > 70 or SSS ≥ 3. In the 2018 validation cohort, 723 patients were scored per NSS and SSS, and the negative predictive value for both was 96%. CONCLUSION: Estimating LNM risk in MCPs by applying clinical characteristics along with limited histologic data can help inform decision-making when considering formal oncologic resection. The NSS and SSS demonstrated comparable predictability of LNM among pT1Nx MCPs. The models require external validation and may be strengthened by incorporating additional endoscopic and pathologic characteristics.

Gastroblastoma with a novel EWSR1-CTBP1 fusion presenting in adolescence.

Gastroblastomas are rare tumors with a biphasic epithelioid/spindle cell morphology that typically present in early adulthood and have recurrent MALAT1-GLI1 fusions. We describe an adolescent patient with Wiskott-Aldrich syndrome who presented with a large submucosal gastric tumor with biphasic morphology. Despite histologic features consistent with gastroblastoma, a MALAT1-GLI1 fusion was not found in this patient's tumor; instead, comprehensive molecular profiling identified a novel EWSR1-CTBP1 fusion and no other significant genetic alterations. The tumor also overexpressed NOTCH and FGFR by RNA profiling. The novel fusion and expression profile suggest a role for epithelial-mesenchymal transition in this tumor, with potential implications for the pathogenesis of biphasic gastric tumors such as gastroblastoma.