Hypermucinous, Goblet Cell-Deficient and Crypt Cell Dysplasias in Inflammatory Bowel Disease are Often Associated with Flat/Invisible Endoscopic Appearance and Advanced Neoplasia on Follow-Up

Nonconventional Dysplasia is Frequently Associated With Goblet Cell Deficient and Serrated Variants of Colonic Adenocarcinoma in Inflammatory Bowel Disease

Various subtypes of nonconventional dysplasia have been recently described in inflammatory bowel disease (IBD). We hypothesized that goblet cell deficient dysplasia and serrated dysplasia may be the primary precursor lesions for goblet cell deficient (GCDAC) and serrated (SAC) variants of colonic adenocarcinoma, respectively. Clinicopathologic features of 23 GCDAC and 10 SAC colectomy cases were analyzed. All dysplastic lesions found adjacent to the colorectal cancers (n = 22 for GCDACs and n = 10 for SACs) were subtyped as conventional, nonconventional, or mixed-type dysplasia. As controls, 12 IBD colectomy cases with well to moderately differentiated adenocarcinoma that lacked any mucinous, signet ring cell, low-grade tubuloglandular, or serrated features while retaining goblet cells throughout the tumor (at least 50% of the tumor) were evaluated. The cohort consisted of 19 (58%) men and 14 (42%) women, with a mean age of 53 years and a long history of IBD (mean duration: 18 y). Twenty-seven (82%) patients had ulcerative colitis. GCDACs (57%) were more often flat or invisible than SACs (10%) and controls (25%; P = 0.023). The GCDAC and SAC groups were more likely to show lymphovascular invasion (GCDAC group: 52%, SAC group: 50%, control group: 0%, P = 0.001) and lymph node metastasis (GCDAC group: 39%, SAC group: 50%, control group: 0%, P = 0.009) than the control group. Notably, GCDACs and SACs were more frequently associated with nonconventional dysplasia than controls (GCDAC group: 77%, SAC group: 40%, control group: 0%, P < 0.001). Goblet cell deficient dysplasia (73%) was the most prevalent dysplastic subtype associated with GCDACs ( P = 0.049), whereas dysplasias featuring a serrated component (60%) were most often associated with SACs ( P = 0.001). The GCDAC group (75%) had a higher rate of macroscopically flat or invisible synchronous dysplasia compared with the SAC (20%) and control (33%) groups ( P = 0.045). Synchronous dysplasia demonstrated nonconventional dysplastic features more frequently in the GCDAC (69%) and SAC (40%) groups compared with the control group (0%; P = 0.016). In conclusion, goblet cell deficient dysplasia and dysplasias featuring a serrated component could potentially serve as high-risk markers for GCDACs and SACs, respectively.

Histopathological Evaluation of Pouch Neoplasia in IBD and Familial Adenomatous Polyposis

BACKGROUND

IPAA is often required for patients with ulcerative colitis or familial adenomatous polyposis after colectomy. This procedure reduces but does not completely eliminate the risk of neoplasia.

OBJECTIVE

This study focuses on the histopathology of neoplasia in the ileal pouch, rectal cuff, and anal transition zone.

DATA SOURCES

We performed a MEDLINE search for English-language studies published between 1981 and 2022 using the PubMed search engine. The terms "ileal pouch-anal anastomosis," "pouchitis," "pouch dysplasia," "pouch lymphoma," "pouch squamous cell carcinoma," "pouch adenocarcinoma," "pouch neoplasia," "dysplasia of rectal cuff," and "colitis-associated dysplasia" were used.

STUDY SELECTION

Human studies of neoplasia occurring in the pouch and para-pouch were selected, and the full text was reviewed. Comparisons were made within and across studies, with key concepts selected for inclusion in this article.

CONCLUSIONS

Neoplasia in the pouch is a rare complication in patients with IPAA. Annual endoscopic surveillance is recommended for familial adenomatous polyposis patients and ulcerative colitis patients with a history of prior dysplasia or carcinoma. In familial adenomatous polyposis, dysplastic polyps of the pouch are visible and readily amenable to endoscopic removal; however, glandular dysplasia in the setting of ulcerative colitis may be invisible on endoscopy. Therefore, random biopsies and adequate tissue sampling of the pouch and rectal cuff are recommended in this setting. The histological diagnosis of IBD-associated dysplasia can be challenging and should be confirmed by at least 1 expert GI pathologist. See video from the symposium.

Pathology and Clinical Significance of Inflammatory Bowel Disease-Associated Colorectal Dysplastic Lesions

Timely diagnosis and effective management of colorectal dysplasia play a vital role in preventing mortality from colorectal cancer in patients with chronic inflammatory bowel disease. This review provides a contemporary overview of the pathologic and endoscopic classification of dysplasia in inflammatory bowel disease, their roles in determining surveillance and management algorithms, and emerging diagnostic and therapeutic approaches that might further enhance patient management.

Recently described types of dysplasia associated with IBD: tips and clues for the practising pathologist

Longstanding inflammatory bowel disease (especially in patients with severely active disease or primary sclerosing cholangitis) is associated with an increased risk of developing dysplasia and adenocarcinoma. This review covers critical clinical aspects, such as risk factors and screening endoscopy basics, emphasising the SCENIC (Surveillance for Colorectal Endoscopic Neoplasia Detection in Inflammatory Bowel Disease International Consensus) guidelines. The histopathological and molecular features of both conventional (adenomatous) dysplasia and the non-conventional subtypes (hypermucinous dysplasia, goblet cell-deficient dysplasia, crypt cell dysplasia, serrated dysplasias) are discussed with an emphasis on challenging diagnostic areas and helpful tips to allow correct categorisation by the practising pathologist.

Characteristics, Reporting, and Potential Clinical Significance of Nonconventional Dysplasia in Inflammatory Bowel Disease

The term nonconventional dysplasia has been coined to describe several underrecognized morphologic patterns of epithelial dysplasia in inflammatory bowel disease (IBD), but to date, the full recognition of these newly characterized lesions by pathologists is uneven. The identification of nonconventional dysplastic subtypes is becoming increasingly important, as they often present as invisible/flat dysplasia and are more frequently associated with advanced neoplasia than conventional dysplasia on follow-up. This review describes the morphologic, clinicopathologic, and molecular characteristics of seven nonconventional subtypes known to date, as well as their potential significance in the clinical management of IBD patients.

Morphological subtypes of colorectal low-grade intraepithelial neoplasia: diagnostic reproducibility, frequency and clinical impact

AIMS

Special histomorphological subtypes of colorectal low-grade intraepithelial neoplasia (LGIN) with variable prognostic impact were recently described in patients with inflammatory bowel disease (IBD) referred to as non-conventional dysplasia. However, they can also be found in patients without IBD. We aimed to analyse the reproducibility, frequency and prognostic impact of non-conventional colorectal LGIN in patients with and without IBD.

METHODS

Six pathologists evaluated 500 specimens of five different LGIN-cohorts from patients with and without IBD. Non-conventional LGIN included hypermucinous, goblet cell-deficient, Paneth cell-rich and crypt cell dysplasia. A goblet cell-rich type and non-conventional LGIN, not otherwise specified were added. Results were compared with the original expert-consented diagnosis from archived pathology records.

RESULTS

Four or more pathologists agreed in 86.0% of all cases. Non-conventional LGIN was seen in 44.4%, more frequently in patients with IBD (52%; non-IBD: 39.3%, p=0.005). In patients with IBD non-conventional LGIN associated with more frequent and earlier LGIN relapse (p=0.006, p=0.025), high-grade intraepithelial neoplasia (p=0.003), larger lesion size (p=0.001), non-polypoid lesions (p=0.019) and additional risk factors (p=0.034). Results were highly comparable with expert-consented diagnoses. In patients without IBD, non-conventional LGIN may indicate a higher risk for concurrent or subsequent colorectal carcinoma (CRC, p=0.056 and p=0.061, respectively). Frequencies and association with high-grade intraepithelial neoplasia or CRC varied between the different LGIN subtypes.

CONCLUSIONS

Non-conventional histomorphology in colorectal LGIN is frequent and highly reproducible. Our results indicate an increased risk for CRC in patients with non-conventional LGIN, probably independent of IBD. We recommend reporting non-conventional LGIN in routine pathology reports.

A vascularized crypt-patterned colon model for high-throughput drug screening and disease modelling

The colon serves as a primary target for pharmaceutical compound screening and disease modelling. To better study colon diseases and develop treatments, engineered in vitro models with colon-specific physiological features are required. Existing colon models lack integration of colonic crypt structures with underlying perfusable vasculature, where vascular-epithelial crosstalk is affected by disease progression. We present a colon epithelium barrier model with vascularized crypts that recapitulates relevant cytokine gradients in both healthy and inflammatory conditions. Using our previously published IFlowPlate384 platform, we initially imprinted crypt topography and populated the patterned scaffold with colon cells. Proliferative colon cells spontaneously localized to the crypt niche and differentiated into epithelial barriers with a tight brush border. Toxicity of the colon cancer drug, capecitabine, was tested and showed a dose-dependent response and recovery from crypt-patterned colon epithelium exclusively. Perfusable microvasculature was then incorporated around the colon crypts followed by treatment with pro-inflammatory TNFα and IFNγ cytokines to simulate inflammatory bowel disease (IBD)-like conditions. We observed in vivo-like stromal basal-to-apical cytokine gradients in tissues with vascularized crypts and gradient reversals upon inflammation. Taken together, we demonstrated crypt topography integrated with underlying perfusable microvasculature has significant value for emulating colon physiology and in advanced disease modelling.

[Conventional and non-conventional dysplasia in patients with inflammatory bowel disease]

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.

Molecular characterization of visible low-grade dysplastic lesions in patients with inflammatory bowel disease

We studied pathogenic gene mutations and tumor mutation burden (TMB) in visible low-grade dysplastic lesions in patients with inflammatory bowel disease (IBD). The dysplastic lesions with histologically normal mucosa in the background (group 1) were compared with dysplastic lesions occurring either in a background of chronic active colitis (group 2) or associated with synchronous carcinomas regardless of the status of the background mucosa (group 3). The TMB in group 3 was consistently higher in comparison to the group 1 and group 2 lesions, although the difference was not statistically significant. There also seem to be different mutation profiles between the groups, indicating different pathways of tumor pathogenesis. More frequent APC mutations were seen in group 1 as compared to other groups and TP53 mutations were seen in groups 2 and 3, but none in group 1. Molecular characterization could potentially be used as an ancillary prognostic marker in challenging cases to guide the further management of IBD patients with visible dysplastic lesions.

Increased Risk of Non-conventional and Invisible Dysplasias in Patients with Primary Sclerosing Cholangitis and Inflammatory Bowel Disease

BACKGROUND AND AIMS

Patients with primary sclerosing cholangitis and inflammatory bowel disease [termed PSC-IBD] have a higher risk of developing colorectal neoplasia than those with IBD alone. The mechanism by which concomitant PSC increases the risk of colorectal neoplasia remains unknown. Seven distinct non-conventional dysplastic subtypes have been recently described in IBD, including crypt cell dysplasia, hypermucinous dysplasia, goblet cell-deficient dysplasia, dysplasia with increased Paneth cell differentiation [DPD], sessile serrated lesion [SSL]-like dysplasia, traditional serrated adenoma [TSA]-like dysplasia, and serrated dysplasia, not otherwise specified [NOS]. Despite the lack of high-grade morphological features, crypt cell, hypermucinous, and goblet cell-deficient dysplasias often show molecular features characteristic of advanced neoplasia [i.e. aneuploidy and KRAS mutations] and are more frequently associated with advanced neoplasia than conventional dysplasia on follow-up. We aimed to characterise clinicopathological features of dysplasia found in PSC-IBD patients.

METHODS

A cohort of 173 PSC-IBD patients were analysed. All dysplastic lesions were subtyped as either conventional or non-conventional dysplasia. The clinicopathological features of PSC-IBD patients with neoplasia were also compared with those of non-PSC IBD patients with neoplasia.

RESULTS

There were 109 [63%] men and 64 [37%] women, with a mean age of 26 years at IBD diagnosis and a long history of IBD [mean duration: 14 years]. Ulcerative colitis was the most common IBD subtype [80%], and the majority of patients [92%] had a history of pancolitis. A total of 153 dysplastic lesions were detected in 54 [31%] patients, 35 [65%] of whom had multifocal dysplasia. One additional patient presented with colorectal cancer [CRC] without a history of dysplasia. Dysplasia was often non-conventional [n = 93; 61%], endoscopically/grossly invisible [n = 101; 66%], and right/proximal-sided [n = 90; 59%]. All seven non-conventional subtypes were identified, including 46 [30%] crypt cell dysplasia, 23 [15%] hypermucinous dysplasia, 12 [8%] goblet cell-deficient dysplasia, seven [5%] DPD, three [2%] TSA-like dysplasia, one [1%] SSL-like dysplasia, and one [1%] serrated dysplasia NOS. Follow-up information was available for 86 lesions, of which 32 [37%] were associated with subsequent detection of advanced neoplasia [high-grade dysplasia or CRC] within a mean follow-up time of 55 months. PSC-IBD patients with neoplasia were more likely to have pancolitis [98%, p = 0.039] and a longer IBD duration [mean: 17 years, p = 0.021] than those without neoplasia [89% and 12 years, respectively]. When compared with a cohort of non-PSC IBD patients with neoplasia, the PSC-IBD group with neoplasia was more often associated with non-conventional [61%, p <0.001], invisible [66%, p <0.001], and right/proximal-sided [59%, p = 0.045] dysplasias [vs 25%, 21%, and 47%, respectively, for the non-PSC IBD group]. The rate of advanced neoplasia was nearly 2-fold higher in the PSC-IBD group [37%] compared with the non-PSC IBD group [22%] [p = 0.035].

CONCLUSIONS

Nearly a third of PSC-IBD patients developed dysplasia, which is often associated with non-conventional dysplastic features, invisible endoscopic/gross appearance, right/proximal-sided colon, multifocality, and advanced neoplasia on follow-up. These findings underscore the importance of recognising these non-conventional subtypes by practising pathologists and the need for careful and frequent endoscopic surveillance, with random biopsies, in PSC-IBD patients.

Increased Histologic Inflammation is an Independent Risk Factor for Non-Conventional Dysplasia in Ulcerative Colitis

AIMS

Several types of non-conventional 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 non-conventional 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 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 non-conventional 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).

CONCLUSIONS

The risk of non-conventional dysplasia is significantly associated with increased inflammation, which may contribute to its higher rates of aneuploidy and malignancy.

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 non-conventional 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 non-conventional 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.

CONCLUSIONS

The rate of undetected dysplasia is not insignificant (13%), suggesting that increased random biopsies may improve the rate of dysplasia detection, including non-conventional dysplasia.

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.