Backwash Is Hogwash: The Clinical Significance of Ileitis in Ulcerative Colitis

MR Enterography in Ulcerative Colitis: Beyond Endoscopy

Ulcerative colitis (UC) is a chronic idiopathic inflammatory bowel disease (IBD) that progressively affects mucosa and submuccosa of the colon and rectum in a continual pattern. In comparison, Crohn disease (CD), the other type of IBD, is a chronic transmural inflammatory disorder that can involve any part of the gastrointestinal tract. MR enterography (MRE) has emerged as an important imaging modality for the diagnosis and detection of disease activity and complications in CD, with comparable results to those of endoscopy. But MRE has been underused for assessment of UC in recent years, and clinicians heavily rely on endoscopic findings for management of UC. Despite UC being considered an endoscopically assessable disease, MRE can provide useful information beyond that obtained with endoscopy about mural or extramural abnormalities, inaccessible parts of the colonic lumen, associated extraintestinal diseases, and superimposed pathologic conditions. Moreover, endoscopy might be contraindicated in some clinical settings due to the risk of colonic perforation. In addition to depicting the features of UC activity in different phases, MRE demonstrates findings of disease chronicity that cannot be achieved with endoscopy, particularly in a patient with colitis of unknown cause. The valuable diagnostic role of MRE to exclude undiagnosed CD in patients with UC who have refractory disease or those with postproctocolectomy complications is also emphasized. Radiologists can play a crucial role in the management of UC with MRE by addressing what is beyond endoscopy. ©RSNA, 2023 Test Your Knowledge questions are available in the supplemental material.

A Practical Index to Distinguish Backwash Ileitis From Crohn's Terminal Ileitis in MR Enterography

BACKGROUND

Differentiating ulcerative colitis-associated "backwash" ileitis (BWI) from Crohn's terminal ileitis (CTI) is a diagnostic challenge and highly affects patient's management. This study aimed to investigate magnetic resonance enterography (MRE) features including ileocecal valve patency index (ICPI) in patients with BWI and CTI and distinguish these entities based on MRE findings.

METHODS

After obtaining institutional review board approval, we reviewed 1654 MREs; 60 patients with pathologically proven BWI (n = 30) and CTI (n = 30) were enrolled. Two radiologists who were blinded to the clinical diagnosis analyzed MREs. We evaluated bowel wall thickness and enhancement pattern, ileocecal valve (ICV) diameter, and lip thickness. Ileocecal valve patency index-T and ICPI-C were calculated to normalize the ICV diameter with respect to terminal ileum (TI) and cecum, respectively. An additional group of non-BWI-UC patients (n = 30) was also included to validate indices.

RESULTS

Circumferential mural thickening (90% vs 1%, P < .001) and inner-wall enhancement (P < .001) of TI were more frequent in BWI patients than CTI. Serosal irregularity (53% vs 13%, P = .002), higher mural thickness (5mm vs 3mm, P < .001), and asymmetric hyperenhancement (P < .001) of TI were more prevalent in CTI than BWI. Ileocecal valve patency and lip atrophy were significantly higher in BWI than CTI and non-BWI-UC groups (both P < .001). Ileocecal valve patency indices-C and ICPI-T indices were able to accurately distinguish BWI from CTI (area under the ROC curve [AUC], 0.864 and 0.847 for ICPI-T and ICPI-C, respectively) and non-BWI-UC (AUC, 0.777 and 0.791 for ICPI-T and ICPI-C, respectively). Ileocecal valve patency indices-T  ≥31.5% were 100% specific to distinguish BWI from CTI, but sensitivity was 63%.

CONCLUSIONS

Magnetic resonance enterography features of ICV and TI can accurately differentiate BWI from CTI. Two practical indices introduced in this study showed high specificity to distinguish BWI from CTI.

Isotretinoin-Induced Distal Ileitis Mimicking Crohn's Disease

Terminal ileitis is a common condition defined as inflammation of the terminal portion of the ileum, which is typically associated with inflammatory bowel disease (IBD), classically Crohn's disease (CD). However, it can have other etiologies, including drug-induced ones. Isotretinoin is an effective and commonly used treatment for acne vulgaris, presenting multiple adverse effects. There have been discussions over its association with enteric inflammation, particularly over IBD emergence risk. We report a case of a previously healthy 17-year-old female who presented transitory clinical, laboratory, imaging, and endoscopic evidence of distal ileitis, temporally related to extended isotretinoin treatment and mimicking CD. Repeated clinical, laboratory, imaging, and endoscopic reassessment after isotretinoin discontinuation confirmed an almost complete resolution of the condition, avoiding IBD misdiagnosis and specific medication initiation. Our case highlights the differential diagnosis of ileitis as being of critical importance to avoid further unnecessary diagnostic investigations and inadequate treatment. Serial re-evaluation may be of key importance to reach a final diagnosis. Although recent literature suggests that isotretinoin is not associated with an increased IBD risk, our case highlights the possibility of it inducing small bowel injury and inflammation, similar to what has been reported with other drugs.

Evidence-based pathogenesis and treatment of ulcerative colitis: A causal role for colonic epithelial hydrogen peroxide

In this comprehensive evidence-based analysis of ulcerative colitis (UC), a causal role is identified for colonic epithelial hydrogen peroxide (H₂O₂) in both the pathogenesis and relapse of this debilitating inflammatory bowel disease. Studies have shown that H₂O₂ production is significantly increased in the non-inflamed colonic epithelium of individuals with UC. H₂O₂ is a powerful neutrophilic chemotactic agent that can diffuse through colonic epithelial cell membranes creating an interstitial chemotactic molecular “trail” that attracts adjacent intravascular neutrophils into the colonic epithelium leading to mucosal inflammation and UC. A novel therapy aimed at removing the inappropriate H₂O₂ mediated chemotactic signal has been highly effective in achieving complete histologic resolution of colitis in patients experiencing refractory disease with at least one (biopsy-proven) histologic remission lasting 14 years to date. The evidence implies that therapeutic intervention to prevent the re-establishment of a pathologic H₂O₂ mediated chemotactic signaling gradient will indefinitely preclude neutrophilic migration into the colonic epithelium constituting a functional cure for this disease. Cumulative data indicate that individuals with UC have normal immune systems and current treatment guidelines calling for the suppression of the immune response based on the belief that UC is caused by an underlying immune dysfunction are not supported by the evidence and may cause serious adverse effects. It is the aim of this paper to present experimental and clinical evidence that identifies H₂O₂ produced by the colonic epithelium as the causal agent in the pathogenesis of UC. A detailed explanation of a novel therapeutic intervention to normalize colonic H₂O₂, its rationale, components, and formulation is also provided.

Critical diagnoses in paediatric gastrointestinal diseases

Gastrointestinal biopsies represent an increasing proportion of the paediatric pathologist's workload, an increase fundamentally due to an expansion of the understanding of the basic clinical, molecular, genetic, and histopathological features of paediatric gastrointestinal disorders. The histological interpretation of endoscopically retrieved gastrointestinal biopsies in children requires a unique set of diagnostic expertise and detailed knowledge of various gastrointestinal disorders that have a predilection for the paediatric population. This article's major role is to highlight the unique problems inherent to paediatric gastrointestinal disorders that require immediate communication with the paediatric surgeon or the gastroenterologist. For this, we tried to cover the most important diseases that a paediatric pathologist might encounter in daily practice. Some of these diseases are relatively rare, such as microvillous inclusion disease and tufting enteropathy, but some are more common such as eosinophilic disorders and inflammatory bowel disease. Awareness of the histopathological features of these diseases, particularly those that are relatively uncommon, is crucial to spare the patient a lengthy and costly evaluation. We made a particular effort to abundantly reference this article should the reader wish to expand on the content of any section.

Highly Multiplexed Image Analysis of Intestinal Tissue Sections in Patients With Inflammatory Bowel Disease

BACKGROUND & AIMS

Significant progress has been made since the first report of inflammatory bowel disease (IBD) in 1859, after decades of research that have contributed to the understanding of the genetic and environmental factors involved in IBD pathogenesis. Today, a range of treatments is available for directed therapy, mostly targeting the overactive immune response. However, the mechanisms by which the immune system contributes to disease pathogenesis and progression are not fully understood. One challenge hindering IBD research is the heterogeneous nature of the disease and the lack of understanding of how immune cells interact with one another in the gut mucosa. Introduction of a technology that enables expansive characterization of the inflammatory environment of human IBD tissues may address this gap in knowledge.

METHODS

We used the imaging mass cytometry platform to perform highly multiplex image analysis of IBD and healthy deidentified intestine sections (6 Crohn's disease compared to 6 control ileum; 6 ulcerative colitis compared to 6 control colon). The acquired images were graded for inflammation severity by analysis of adjacent H&E tissue sections. We assigned more than 300,000 cells to unique cell types and performed analyses of tissue integrity, epithelial activity, and immune cell composition.

RESULTS

The intestinal epithelia of patients with IBD exhibited increased proliferation rates and expression of HLA-DR compared to control tissues, and both features were positively correlated with the severity of inflammation. The neighborhood analysis determined enrichment of regulatory T cell interactions with CD68⁺ macrophages, CD4⁺ T cells, and plasma cells in both forms of IBD, whereas activated lysozyme C⁺ macrophages were preferred regulatory T cell neighbors in Crohn's disease but not ulcerative colitis.

CONCLUSIONS

Altogether, our study shows the power of imaging mass cytometry and its ability to both quantify immune cell types and characterize their spatial interactions within the inflammatory environment by a single analysis platform.

Discrete terminal ileal ulcers in patients diagnosed with ulcerative colitis: clinical significance and natural course

BACKGROUND

Terminal ileal (TI) ulcers are occasionally detected in asymptomatic individuals and mostly resolve without any treatment. In patients with ulcerative colitis (UC), TI ulcers are infrequently observed without evidence of backwash ileitis. However, the clinical significance and natural course of the lesions are unclear. The aim of our study was to evaluate the frequency and clinical implications of TI ulcers in patients with UC.

METHODS

We retrospectively reviewed 397 patients with UC via successful TI intubation during colonoscopy. We compared the clinical characteristics of patients manifesting TI ulcers with those who did not. The natural course of TI lesions was also investigated during the follow-up periods.

RESULTS

Forty-one patients (10.3%) showed TI ulcers without evidence of inflammation in the right colon. The patients with and without TI ulcers were not different in terms of baseline characteristics, disease activity and extent at the time of the UC diagnosis, proximal extension, Mayo endoscopic score at the last endoscopic examination, medication history, UC-related hospitalization, and relapse during follow-up periods. Of the 30 patients who underwent follow-up colonoscopy in patients with TI ulcers, 23 (76.7%) showed resolution of TI ulcer. In addition, patients with remaining TI ulcers did not differ in disease activity and biopsy results compared with those with resolving TI ulcers.

CONCLUSIONS

Discrete TI ulcers are more common in patients with UC, compared with the healthy cohort. No significant clinical impact on disease extension and severity is found.

Prognostic Value of Terminal Ileal Inflammation in Patients with Ulcerative Colitis

Background/Aims

Few studies have investigated terminal ileal lesions and their prognostic value in patients with ulcerative colitis (UC). We evaluated the clinical significance of these lesions as a prognostic factor in patients with UC who were in clinical remission.

Methods

We retrospectively selected 567 of 4,066 colonoscopy reports that included positive findings from orificial observations of the terminal ileum (TI) and appendix in patients with UC. We finally recruited patients who were in clinical remission (n=204). We compared the clinical courses, including relapse and other prognostic parameters associated with UC, between the groups.

Results

The baseline patient characteristics were not significantly different between patients with (n=69, TI+ group) and without TI lesions (n=135, TI- group), although there were more never-smokers in the TI+ group (n=57 [82.6%] in the TI+ group; n=86 [63.7%] in the TI- group; p=0.005). Of note, appendiceal orifice inflammation (AOI) was less frequently found in the TI+ group (14.5%) than in the TI- group (71.9%, p<0.001). The cumulative relapse rate was numerically higher in the TI- group, but it was not significantly different according to the Kaplan-Meier analysis (p=0.116). Multivariate Cox regression analysis also revealed advanced age at diagnosis as the most significant factor (adjusted hazard ratio, 0.964; 95% confidence interval, 0.932 to 0.998; p=0.037), but neither TI inflammation nor AOI were significantly associated with the cumulative relapse rate in patients with UC in clinical remission.

Conclusions

For patients with UC in clinical remission, neither terminal ileal lesions nor AOI had significant clinical or predictive value for future relapse.

Clinicopathologic Features and Diagnostic Implications of Pyloric Gland Metaplasia in Intestinal Specimens

Pyloric gland metaplasia (PGM) is a histopathologic change usually seen after inflammatory injury and, although described in association with inflammatory bowel disease (IBD) and particularly Crohn disease (CD), its significance is still debated. We evaluated long-term correlates of PGM in a large cohort of 601 intestinal specimens, 227 (37.8%) biopsies, and 374 (62.2%) resections, from 567 different patients, 328 (57.8%) male and 239 (42.2%) female, with a mean age of 43.4±15.8 years. During mean clinical follow-up of 83.5±48.1 months, 511 (90.1%) patients were diagnosed with IBD, 457 (89.4%) with CD, and 53 (10.4%) with ulcerative colitis. In multivariate analysis, IBD patients with PGM were younger (P<0.001) and more often had severely active inflammation (P=0.002) compared with non-IBD patients, whereas, among IBD patients, those with ulcerative colitis were more likely to have PGM in a biopsy (P<0.001) or in the colorectum (P=0.009), compared with CD patients. Kaplan-Meier analyses showed that incidental PGM in a biopsy was more likely to predict IBD in patients younger than 50 years (P<0.001) and those without a history of bowel surgery (P<0.001) and also more likely to signify CD in patients younger than 50 years (P=0.004), those without a history of bowel surgery (P=0.020), and when identified in the small intestine (P=0.032). In conclusion, intestinal PGM warrants a high suspicion for IBD and specifically CD, however, it should be interpreted with caution, especially in older patients or those with a history of prior intestinal surgery and in colorectal biopsies or specimens lacking severely active inflammation.

Ulcerative Colitis: Making the Diagnosis

Ulcerative colitis is an inflammatory condition of the colon. The diagnosis of ulcerative colitis is based on clinical presentation, endoscopic evaluation, and histologic parameters in the absence of demonstrable alternate etiology. The differential diagnosis remains broad, and infection in particular must be considered and excluded. Although laboratory and radiographic findings can aid in the diagnosis of ulcerative colitis, endoscopy remains the gold standard for diagnosis. A correct diagnosis and disease staging are imperative because these factors affect treatment options and prognosis.

Microscopic/"Backwash" Ileitis and Its Association With Colonic Disease in New Onset Pediatric Ulcerative Colitis

BACKGROUND

Microscopic ileitis and its association with pancolitis in adults with ulcerative colitis (UC) have been described. The incidence of ileitis and associations with colonic disease in pediatric UC have, however, not been thoroughly investigated. This study was undertaken to examine the prevalence of microscopic ileal inflammation at the time of initial diagnosis in a cohort of children with UC.

METHODS

We reviewed colonoscopy and biopsy data at time of diagnosis from 105 children and young adults with treatment naïve UC; ileal and colonic mucosal biopsies were available on all patients. Ileal mucosal biopsies were examined for the presence and severity of ileal inflammation, and other histologic features. Concurrently obtained colonic mucosal biopsies were assessed to define the severity, distribution, and extent of disease; endoscopic and clinical follow-up data were reviewed.

RESULTS

A total of 107 ileal mucosal biopsies and 693 corresponding colonic mucosal biopsies were examined. Seventeen of 105 patients (16%) were found to have ileal inflammation (mean age = 10.4 years, 59% girls), 14 (82%) of whom had histologic pancolitis. The presence of ileal inflammation was significantly associated with endoscopic pancolitis (P = 0.02). The association between histologic pancolitis, severity of active inflammation in the cecum, and ascending colon suggested a possible association with ileal inflammation (P = 0.06, 0.07, and 0.08 respectively), but did not reach statistical significance.

CONCLUSION

Patients with new onset UC may have microscopic ileal inflammation at time of diagnosis, even if the terminal ileum appears macroscopically normal. The presence of endoscopic pancolitis is associated with the presence of histologic ileitis. In contrast to existing studies in adults, an association between the presence of ileitis and the histologic severity or the histologic extent of colitis was not observed. Children with microscopic ileitis in the context of UC do not need to be reclassified as "indeterminate colitis" or Crohn disease.

Increase in chromogranin A- and serotonin-positive cells in pouch mucosa of patients with ulcerative colitis undergoing proctocolectomy

BACKGROUND

Inflammatory bowel disease (IBD) is associated with neuroendocrine cell hyperplasia.

AIMS

We investigated neuroendocrine cells in J-pouches of patients with ulcerative colitis undergoing restorative proctocolectomy and ileal pouch-anal anastomosis.

METHODS

Sections from pouch biopsies of 17 patients and ileal biopsies of 17 active IBD patients and 16 controls were processed by immunohistochemistry for chromogranin A (CgA) and serotonin. Mucosal tryptophan hydroxylase (TpH)-1 and serotonin-selective reuptake transporter (SERT) transcripts were measured by quantitative RT-PCR. TpH-1 and SERT transcripts were detected in pouch biopsies cultured with infliximab or its isotype control, while interleukin (IL)-6 and IL-8 were measured in biopsy supernatants.

RESULTS

A significant increase in CgA-positive cells and serotonin-positive cells was observed in both pouch and IBD ileum compared to control ileum. Significantly raised transcripts of TpH-1, but not SERT, were found in IBD ileum in comparison to control ileum, with no significant difference between pouch and IBD ileum. Infliximab had no influence on ex vivo pouch expression of TpH-1 and SERT, nor on the production of IL-6 and IL-8.

CONCLUSION

We here demonstrated neuroendocrine cell hyperplasia in pouch mucosa. Further studies are needed to clarify the pathophysiological implication of this finding.