Histologic changes in defunctioned rectums in patients with inflammatory bowel disease: a clinicopathologic study of 82 patients with long-term follow-up

ECCO Topical Review on Clinicopathological Spectrum and Differential Diagnosis of Inflammatory Bowel Disease

INTRODUCTION

Many diseases can imitate inflammatory bowel disease [IBD] clinically and pathologically. This review outlines the differential diagnosis of IBD and discusses morphological pointers and ancillary techniques that assist with the distinction between IBD and its mimics.

METHODS

European Crohn's and Colitis Organisation [ECCO] Topical Reviews are the result of an expert consensus. For this review, ECCO announced an open call to its members and formed three working groups [WGs] to study clinical aspects, pathological considerations, and the value of ancillary techniques. All WGs performed a systematic literature search.

RESULTS

Each WG produced a draft text and drew up provisional Current Practice Position [CPP] statements that highlighted the most important conclusions. Discussions and a preliminary voting round took place, with subsequent revision of CPP statements and text and a further meeting to agree on final statements.

CONCLUSIONS

Clinicians and pathologists encounter a wide variety of mimics of IBD, including infection, drug-induced disease, vascular disorders, diverticular disease, diversion proctocolitis, radiation damage, and immune disorders. Reliable distinction requires a multidisciplinary approach.

Diversion proctocolitis and the problem of the forgotten rectum in inflammatory bowel diseases: A systematic review

Background and aims

Diversion proctocolitis (DP) is a non‐specific mucosal inflammation arising in the defunctionalized colon and/or rectum following faecal diversion (colostomy, ileostomy). Differential diagnosis of DP from the underlying disease in patients with inflammatory bowel diseases (IBD) is often unclear. As a result, it might be difficult to undertake any specific treatment. We aimed to systematically review the literature evidence on DP in IBD patients.

Methods

For this qualitative systematic review, we searched PubMed, EMBASE and Scopus to identify all studies published until July 2021 including IBD patients affected by DP.

Results

Overall, 37 papers published between 1982 and 2021 were included. A total of 1.211 IBD patients were included: 613 UC (50.6%), 524 CD (43.3%), 66 IBD‐unclassified (IBD‐U) (5.4%), 8 unspecified patients (0.7%). Most patients with DP are asymptomatic, although inflammation is detectable in almost all patients with a rectal stump. Reduced short‐chain fatty acids and an altered microbiome, may trigger mucosal inflammation and have been proposed as causing factors. An increased risk of developing cancer on DP has been reported in patients with a history of previous dysplasia/cancer.

Conclusions

The etiopathogenesis of DP is still unknown. The efficacy of mesalamine, corticosteroids or short‐chain fatty acids has not been proven by randomized trials yet. Since the incidence of cancer of the rectal stump can reach 4.5 per 1.000 diverted patients‐year, IBD patients undergoing subtotal colectomy with end‐ileostomy should undergo close endoscopic surveillance, being eventually counseled for surgery with or without the restoration of the intestinal continuity.

Pathophysiology, clinical presentation and management of diversion colitis: a review of current literature

INTRODUCTION

Diversion colitis is a non-specific inflammation of a de-functioned segment of intestine after diversion of the faecal stream.

AIM

The aim of this study was to review the current level of knowledge about diversion colitis.

METHODS

A literature search of relevant literature in the English language was carried out on PUBMED, MEDLINE and EMBASE. The following keywords were used: diversion colitis; disuse colitis; proctitis; colonic bacterial flora; stoma; de-functioned colon; faecal diversion; short chain fatty acids and lymphoid follicular hyperplasia.

RESULTS

In total 35 articles met the inclusion criteria. 22 were case series, 9 were case reports, 2 were retrospective analysis and 2 were prospective randomized controlled studies. Diversion colitis is invariably present in all diverted segments of the colon. It is usually asymptomatic but can present with tenesmus, rectal discharge, bleeding per rectum and abdominal pain. Major macroscopic changes include mucosal nodularity, erythema and friability. Microscopic features are predominantly those of lymphoid follicular hyperplasia, apthous ulceration and chronic inflammatory changes, mostly limited to sub mucosa. Treatment modalities include surveillance for asymptomatic patients, restoration of bowel continuity for severely symptomatic cases and the use of short chain fatty acid (SCFA) enemas in selected cases.

CONCLUSION

The clinical presentation of diversion colitis varies significantly. In symptomatic patients short chain fatty acid enema may help. Further prospective studies are required for evaluation.

Ulcerative colitis or Crohn's disease? Pitfalls and problems

The interpretation of colorectal biopsies taken for the initial diagnosis of chronic idiopathic inflammatory bowel disease (IBD) is challenging. Subclassification of IBD as ulcerative colitis (UC) or Crohn's disease, which may be particularly difficult, is the subject of this review. Biopsies taken at first presentation are emphasised, partly because their features have not been modified by time or treatment. Aspects of longstanding disease and of resections are also mentioned. The first part of the review comprises background considerations and a summary of histological features that are discriminant, according to published evidence, between UC and Crohn's disease in initial biopsies. Pitfalls and problems associated with making the distinction between UC and Crohn's disease are then discussed. These include: mimics of IBD; inadequate clinical details; unreliable microscopic features; absence of histological changes in early IBD; discontinuity in UC; cryptolytic granulomas; differences between paediatric and adult UC; reliance on ileal and oesophagogastroduodenal histology; and atypical features in IBD resections. Avoidance by pathologists of known pitfalls should increase the likelihood of accurate and confident subclassification of IBD, which is important for optimum medical and surgical management.

Inflammatory bowel disease biopsies: updated British Society of Gastroenterology reporting guidelines

Accurate histopathological assessment of biopsies is important for the diagnosis, subclassification, and management of chronic idiopathic inflammatory bowel disease (IBD). British Society of Gastroenterology (BSG) guidelines for the initial histopathological diagnosis of IBD were published in 1997. Changes since then include: more widespread use of full colonoscopy; greater recognition of the effects of time and treatment; improved documentation of variations in anatomical distribution; better understanding of the mimics of IBD; significant progress in clinical management; and modifications of terminology. Accordingly, an update is required. These revised guidelines aim to optimise the quality and consistency of reporting of biopsies taken for the initial diagnosis of IBD by summarising the literature and making recommendations based on the available evidence. Advice from existing clinical guidelines is also taken into account. Among the subjects discussed are: distinguishing IBD from other colitides, particularly infective colitis; subclassification of IBD (as ulcerative colitis, Crohn's disease, or IBD unclassified); the discriminant value of granulomas; aspects of disease distribution, including discontinuity in ulcerative colitis; time-related changes; differences between paediatric and adult IBD; the role of ileal and upper gastrointestinal biopsies; differential diagnoses such as diverticular colitis and diversion proctocolitis; and dysplasia. The need to correlate the histological features with clinical and endoscopic findings is emphasised. An approach to the conclusion of an IBD biopsy report based on the acronym Pattern, Activity, Interpretation, Dysplasia (PAID) is suggested. The key recommendations are listed at the end of the document.

MicroRNA expression patterns in indeterminate inflammatory bowel disease

A diagnosis of idiopathic inflammatory bowel disease requires synthesis of clinical, radiographic, endoscopic, surgical, and histologic data. While most cases of inflammatory bowel disease can be specifically classified as either ulcerative colitis or Crohns disease, 5-10% of patients have equivocal features placing them into the indeterminate colitis category. This study examines whether microRNA biomarkers assist in the classification of classically diagnosed indeterminate inflammatory bowel disease. Fresh frozen colonic mucosa from the distal-most part of the colectomy from 53 patients was used (16 indeterminate colitis, 14 Crohns disease, 12 ulcerative colitis, and 11 diverticular disease controls). Total RNA extraction and quantitative reverse-transcription-PCR was performed using five pairs of microRNA primers (miR-19b, miR-23b, miR-106a, miR-191, and miR-629). Analysis of variance was performed assessing differences among the groups. A significant difference in expressions of miR-19b, miR-106a, and miR-629 was detected between ulcerative colitis and Crohns disease groups (P<0.05). The average expression level of all five microRNAs was statistically different between indeterminate colitis and Crohns disease groups (P<0.05); no significant difference was present between indeterminate and ulcerative colitis groups. Among the 16 indeterminate colitis patients, 15 showed ulcerative colitis-like and one Crohns disease-like microRNA pattern. MicroRNA expression patterns in indeterminate colitis are far more similar to those of ulcerative colitis than Crohns disease. MicroRNA expression patterns of indeterminate colitis provide molecular evidence indicating that most cases are probably ulcerative colitis-similar to the data from long-term clinical follow-up studies. Validation of microRNA results by additional long-term outcome data is needed, but the data presented show promise for improved classification of indeterminate inflammatory bowel disease.

Biopsy interpretation of colonic biopsies when inflammatory bowel disease is excluded

The interpretation of colonic biopsies related to inflammatory conditions can be challenging because the colorectal mucosa has a limited repertoire of morphologic responses to various injurious agents. Only few processes have specific diagnostic features, and many of the various histological patterns reflect severity and duration of the disease. Importantly the correlation with endoscopic and clinical information is often cardinal to arrive at a specific diagnosis in many cases.

Microcarcinoids associated with diversion colitis in a patient with Crohn's disease

Diversion colitis is an iatrogenic disorder related to surgical diversion of the faecal stream from the colorectal mucosa, first described by Morson in 1972. Inflammation of the defunctioned mucosa seems to be related to deprivation of luminal nutrients, in particular short chain fatty acids. Histologic abnormalities include damage of the epithelium and reparative changes with crypt distortion and branching, a mixed acute and chronic inflammatory infiltrate with crypt abscesses and lymphoid hyperplasia, Paneth cell metaplasia and thickening of the muscularis mucosae. We report a case of diversion colitis in a 51-year-old female with Crohn's disease with multiple submucosal microcarcinoids in the rectal stump 17 years after diversion and discuss the hypothesis that hyperplastic and neoplastic lesions of neuroendocrine cells can result from proliferative response to chronic inflammation and repair, as well as epithelial neoplasms.

Pathology of inflammatory bowel disease

Inflammatory bowel disease in childhood refers to ulcerative colitis, Crohn's disease, and colitis of an indeterminate type. Their gross and microscopic features are discussed along with the differential diagnosis from other childhood conditions associated with bloody diarrhea.

Pitfalls in the interpretation of nonneoplastic mucosal biopsies in inflammatory bowel disease

This review provides a summary of common diagnostic problems encountered by both pathologists and gastroenterologists when evaluating patients with diarrhea and in whom inflammatory bowel disease (IBD) is suspected. The two most common forms of IBD, ulcerative colitis (UC) and Crohn's disease (CD), may, in certain settings, show overlapping endoscopic and pathologic features, potentially resulting in diagnostic confusion. For instance, some cases of UC may show unusual CD-like features, such as rectal sparing, discontinuous disease, aphthous ulceration, ileal or extracolonic involvement, and granulomatous inflammation, all of which may be evident in mucosal biopsy specimens. CD may also present as a diffuse, superficial pancolitis with ileal sparing that mimics the endoscopic and histologic appearance of UC. Furthermore, other forms of colitis, such as microscopic colitis, diverticulitis, diversion colitis, and nonsteroidal anti-inflammatory drug (NSAID)-induced colonic injury may also show IBD-like changes in mucosal biopsies. The potential diagnostic pitfalls faced by physicians, as well as features that aid in the distinction among these entities, are discussed in detail in this review.

Diagnostic difficulties in inflammatory bowel disease pathology

This review summarizes some of the common diagnostic problems encountered by pathologists when evaluating patients with chronic colitis and in whom inflammatory bowel disease (IBD) is either suspected or within the differential diagnosis. Both ulcerative colitis (UC) and Crohn's disease (CD) show characteristic, but non-specific, pathological features that may overlap and result in a diagnosis of 'indeterminate colitis' (IC). However, other reasons why pathologists may entertain a diagnosis of IC include failure to recognize or accept certain 'hardcore' histological features as indicative of CD, an attempt to classify cases of chronic colitis based on mucosal biopsy material or in the absence of adequate clinical and radiographic information, and the presence of other disease processes that mask, or mimic, IBD. In addition, some cases of UC may show unusual CD-like features, such as discontinuous or patchy disease, ileal inflammation, extracolonic inflammation, granulomatous inflammation in response to ruptured crypts, aphthous ulcers, or transmural inflammation. Furthermore, other forms of colitis, such as microscopic colitis, diverticulitis and diversion colitis may, on occasion, also show IBD-like changes. The clinical and pathological features that aid in the distinction between these entities, and others, are covered in detail in this review.

In vivo colonoscopic optical coherence tomography for transmural inflammation in inflammatory bowel disease

BACKGROUND & AIMS

Transmural inflammation, a distinguishing feature of Crohn's disease (CD), cannot be assessed by conventional colonoscopy with mucosal biopsy. Our previous ex vivo study of histology-correlated optical coherence tomography (OCT) imaging on colectomy specimens of CD and ulcerative colitis (UC) showed that disruption of the layered structure of colon wall on OCT is an accurate marker for transmural inflammation of CD. We performed an in vivo colonoscopic OCT in patients with a clinical diagnosis of CD or UC using the previously established, histology-correlated OCT imaging criterion.

METHODS

OCT was performed in 40 patients with CD (309 images) and 30 patients with UC (292 images). Corresponding endoscopic features of mucosal inflammation were documented. Two gastroenterologists blinded to endoscopic and clinical data scored the OCT images independently to assess the feature of disrupted layered structure.

RESULTS

Thirty-six CD patients (90.0%) had disrupted layered structure, whereas 5 UC patients (16.7%) had disrupted layered structure (P < .001). Using the clinical diagnosis of CD or UC as the gold standard, the disrupted layered structure on OCT indicative of transmural inflammation had a diagnostic sensitivity and specificity of 90.0% (95% CI: 78.0%, 96.5%) and 83.3% (95% CI: 67.3%, 93.3%) for CD, respectively. The kappa coefficient in the interpretation of OCT images was 0.80 (95% CI: 0.75, 0.86, P < .001).

CONCLUSIONS

In vivo colonoscopic OCT is feasible and accurate to detect disrupted layered structure of the colon wall indicative of transmural inflammation, providing a valuable tool to distinguish CD from UC.

The myenteric plexus of the rat colon after fecal stream diversion: a morpho-quantitative study

The myenteric plexus undergoes adaptive changes under several conditions. Mucosal and muscular alterations of the colon have been described after fecal stream diversion but studies concerning the myenteric plexus after this procedure are scarce. Therefore, 28 Wistar rats were submitted to fecal diversion and followed for different periods (30, 60, 120 and 180 days), in order to study the myenteric plexus of the excluded segments. Seven non-operated rats were employed as control. The myenteric plexus was subsequently evaluated with the NADH and NADPH histochemical techniques. The colonic area of excluded segments is significantly decreased. The density of NADH-stained neurons continuously increases during the entire postoperative period but does not match the extent of surface reduction. Neuronal area measurements suggest hypertrophy of the remaining neurons in the late postoperative period. Morphological alterations of myenteric ganglia and neurons were also evident. An important surface area reduction combined with slight density increase points toward significant neuronal loss after fecal diversion. While studies correlating neuronal loss and functional changes are still lacking, surgeons should bear in mind the modifications of the myenteric plexus when performing fecal stream diversion surgeries.

Ex vivo histology-correlated optical coherence tomography in the detection of transmural inflammation in Crohn's disease

BACKGROUND AND AIMS

Distinguishing Crohn's disease (CD) from ulcerative colitis (UC) can be difficult. Transmural inflammation, a key feature of CD, cannot be assessed by conventional colonoscopy with biopsy. Optical coherence tomography (OCT) provides high-resolution, cross-sectional images of the gut wall and might become a new diagnostic tool. The aims of this study were to perform histology-correlated OCT on surgical specimens of CD and UC and to determine its diagnostic accuracy.

METHODS

Colectomy specimens from patients with a preoperative diagnosis of CD (N = 24) or UC (N = 24) were studied with OCT in the operating room. OCT and histopathology were assessed blindly, and diagnostic accuracy of OCT was assessed.

RESULTS

Eight preoperatively identified UC patients (33%) with transmural inflammation on postoperative histology were diagnosed with CD, and all 8 had a disrupted layered structure on OCT, a characteristic feature of transmural disease. Sixteen UC patients (67%) had superficial inflammation on histology; of them, 13 (81%) had an intact layered structure on OCT. All 24 preoperative CD patients had transmural inflammation on histology, and 23 (96%) had a disrupted layered structure on OCT. Of 585 histology-OCT image sets from the 48 patients, 152 sets (26%) had transmural inflammation on histology. The sensitivity and specificity for OCT to detect transmural disease were 86% and 91%, respectively.

CONCLUSIONS

Transmural inflammation, as characterized by disruption of the layered structure of colon wall on OCT, is an accurate marker for the diagnosis of CD. Ex vivo OCT predicted transmural inflammation on postoperative histopathology.