Facing Terminal Ileitis: Going Beyond Crohn's Disease

Evaluation of Acute Terminal Ileitis in Hospitalized Patients: Development of a Predictive Model to Distinguish Crohn's Disease from Other Etiologies

Background/Objectives: Terminal ileitis (TI) is often identified on CT scans in emergency settings. Diagnosing Crohn's disease (CD) as a cause of TI is crucial due to its significant long-term implications. This study aimed to differentiate CD from other causes of acute TI and develop a predictive model for CD diagnosis. Methods: A retrospective case-control study was conducted at Shamir Medical Center including adults diagnosed with acute TI from January 2012 to December 2020. Patients with a history of inflammatory bowel disease or prior intestinal surgery were excluded. Patients were categorized into CD and non-CD groups based on their subsequent clinical course. A logistic regression model was developed and subsequently validated with additional patients hospitalized between 2021 and 2023. Results: Among 135 patients, 37 (27.4%) were diagnosed with CD. CD patients were younger (median age 27 vs. 39 years, p = 0.003), predominantly male (83.8% vs. 51%, p = 0.001), and had higher rates of chronic abdominal pain, diarrhea, anemia, and weight loss prior to hospitalization. Significant laboratory differences included higher platelet counts (p = 0.006) and lower mean corpuscular volume (MCV) (p = 0.001) in CD patients. Radiologic signs of complicated disease were more common in CD (35.1% vs. 4.1%, p < 0.001). The predictive model incorporating gender, abdominal pain history, and MCV showed an area under the curve (AUC) of 0.87, with a sensitivity of 100% and specificity of 63.6% in the validation group of 18 patients. Conclusions: This study identified key predictors of CD in patients presenting with acute TI and developed a predictive model with a substantial diagnostic capability. Use of this model for early identification and treatment of CD may potentially improve patient outcomes. Further prospective validation of this model is warranted.

Terminal Ileitis as the Exclusive Manifestation of COVID-19 in Children

The clinical presentation, organ involvement, and severity of disease caused by SARS-CoV-2 are highly variable, ranging from asymptomatic or mild infection to respiratory or multi-organ failure and, in children and young adults, the life-threatening multisystemic inflammatory disease (MIS-C). SARS-CoV-2 enters cells via the angiotensin-converting enzyme-2 receptor (ACE-2), which is expressed on the cell surfaces of all organ systems, including the gastrointestinal tract. GI manifestations have a high prevalence in children with COVID-19. However, isolated terminal ileitis without other manifestations of COVID-19 is rare. In March 2023, two previously healthy boys (aged 16 months and 9 years) without respiratory symptoms presented with fever and diarrhea, elevated C-reactive protein levels, and low procalcitonin levels. Imaging studies revealed marked terminal ileitis in both cases. SARS-CoV-2 (Omicron XBB.1.9 and XBB.1.5 variants) was detected by nucleic acid amplification in throat and stool samples. Both patients recovered fast with supportive measures only. A differential diagnosis of acute abdominal pain includes enterocolitis, mesenteric lymphadenitis, appendicitis, and more. During SARS-CoV-2 epidemics, this virus alone may be responsible for inflammation of the terminal ileum, as demonstrated. Coinfection with Campylobacter jejuni in one of our patients demonstrates the importance of a complete microbiological workup.

Diagnostic Value of Ileal Lesions Found during Colonoscopy with Reference to Endoscopic Indications and Findings

The diagnostic value of ileoscopy is not well established, and its routine practice is controversial. We aimed to investigate the diagnostic value of biopsy for macroscopically abnormal lesions in the terminal ileum and to identify the association between endoscopic indications and findings and the presence of significant disease. This retrospective study included 551 patients who underwent biopsy of abnormal lesions in the terminal ileum (TI) during colonoscopy between February 2000 and June 2019. Biopsy results were analyzed in relation to the endoscopic indications and gross findings. Significant disease was defined as a case in which a specific disease was suspected or confirmed by the biopsy results, requiring additional examination or treatment. Among the 551 biopsies from macroscopically abnormal lesions in the TI, 44 (8.0%) had significant diseases. The frequency of significant disease was high in patients with clinically suspected inflammatory bowel disease (IBD) (50.0%), anemia (31.6%), right lower quadrant (RLQ) pain (28.6%), and radiological abnormalities in the TI (27.5%). The frequency of Crohn's disease (CD) was high in patients with clinically suspected IBD. A concurrent abnormality in the ileocecal valve (ICV) (14.3%) and the presence of an ulcer (14.2%), mass, or polyp (25.4%) correlated with a high incidence of significant disease, particularly CD. In cases of suspected IBD, anemia, RLQ pain, and radiologic abnormalities in the TI, there is a high possibility of significant disease. Ulcers, masses, polyps, and concurrent abnormalities in the ICV were also associated with significant disease.

Revised Algorithmic Approach to Differentiate Between Nonspecific and Specific Etiologies of Chronic Terminal Ileitis

INTRODUCTION

Chronic isolated terminal ileitis (TI) may be seen in Crohn's disease (CD) and intestinal tuberculosis (ITB) in addition to other etiologies that may be managed symptomatically. We developed a revised algorithm to distinguish patients with a specific etiology from a nonspecific etiology.

METHODS

Patients with chronic isolated TI followed up from 2007 to 2022 were retrospectively reviewed. A specific (ITB or CD) diagnosis was made based on standardized criteria, and other relevant data were collected. Using this cohort, validation of a previously suggested algorithm was conducted. Furthermore, based on the results of a univariate analysis, a multivariate analysis with bootstrap validation was used to develop a revised algorithm.

RESULTS

We included 153 patients (mean age 36.9 ± 14.6 years, males-70%, median duration-1.5 years, range: 0-20 years) with chronic isolated TI of whom 109 (71.2%) received a specific diagnosis (CD-69, ITB-40). On multivariate regression and validation statistics with a combination of clinical, laboratory, radiological, and colonoscopic findings, an optimism corrected c-statistic of 0.975 and 0.958 was obtained with and without histopathological findings, respectively. Revised algorithm, based on these, showed sensitivity, specificity, positive and negative predictive values, and overall accuracy of 98.2% (95% CI: 93.5-99.8), 75.0% (95% CI: 59.7-86.8), 90.7% (95% CI: 85.4-94.2), 94.3% (95% CI: 80.5-98.5) and 91.5%(95% CI:85.9-95.4), respectively. This was more sensitive and specific than the previous algorithm (accuracy 83.9%, sensitivity 95.5%, and specificity 54.6%).

DISCUSSION

We developed a revised algorithm and a multimodality approach to stratify patients with chronic isolated TI into specific and nonspecific etiologies with an excellent diagnostic accuracy, which could potentially avoid missed diagnosis and unnecessary side effects of treatment.

Isolated Terminal Ileitis in Children

Isolated terminal ileitis in adults is a well described entity that rarely progresses to Crohn disease (CD), and pediatric literature on this topic is very limited. We describe the prevalence, clinical, endoscopic, histologic, and radiological features, along with long-term outcome of isolated terminal ileitis in our institution. We reviewed charts of 956 children who underwent colonoscopy from 2013 to 2017. Thirty-three children had isolated histologically-defined terminal ileitis. Seventeen children were diagnosed with CD and 16 children had idiopathic terminal ileitis. Children with CD had higher prevalence of abnormal C-reactive protein levels, severe inflammation, and radiological evidence of bowel wall thickening compared with children with idiopathic ileitis. Children with idiopathic ileitis did not develop CD over a follow-up period of 83 months. In contrast to adults, CD is common in children with isolated terminal ileitis and those with idiopathic ileitis do well over long-term.

Terminal ileitis and cytotoxic lesion of corpus callosum as the presenting features of Multisystem inflammatory syndrome in children (MIS-C): a case report

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) is a post-viral inflammatory vasculopathy characterized by persistent fever, multiorgan dysfunction, significant laboratory markers of inflammation, lack of an alternative diagnosis, and prior SARS-CoV-2 infection or exposure in children and adolescents. The most common early symptoms include a prolonged fever, as well as dermatologic, mucocutaneous, and gastrointestinal symptoms such abdominal pain, vomiting, and diarrhea.

CASE PRESENTATION

We present a pediatric patient with multisystem inflammatory syndrome with the development of abdominal pain and seizure who was found to have a circumferential wall thickening of the terminal ileum and ileocecal junction in abdominal CT scan. The brain MRI of the patient showed cytotoxic lesions of the corpus callosum (CLOCC) which had hypersignal intensity with a few diffusion restrictions in the splenium of the corpus callosum.

CONCLUSION

This case is being reported to raise awareness of MIS-C presenting characteristics. Given the rising number of MIS-C patients and a lack of understanding regarding early diagnostic clinical characteristics and therapy, further research into clinical presentations, treatment, and outcomes is urgently needed.

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.

Differential to Terminal Ileitis: Terminal Ileum Neuroendocrine Tumor Identified on Screening Colonoscopy

Background: Asymptomatic patients at average risk of developing colorectal cancer are encouraged to undergo screening colonoscopy beginning at age 45 years. While ileal intubation is often considered the gold standard for a complete colonoscopy, the relatively low diagnostic yield has prevented widespread adoption. Small bowel cancers, including neuroendocrine tumors, may present incidentally as terminal ileitis on routine colonoscopy with terminal ileum intubation. Neuroendocrine tumors, the most common primary neoplasm of the small intestine, are often asymptomatic or present as nonspecific abdominal pain in the sixth or seventh decade of life. Case Report: A 51-year-old asymptomatic male with unremarkable physical examination underwent screening colonoscopy that revealed scattered ulcerations of the terminal ileum. Immunohistochemistry of the lesion was consistent with well-differentiated neuroendocrine tumor, World Health Organization Grade I. DOTATATE positron emission tomography/computed tomography demonstrated avid adjacent right mesenteric lymph node and avid focal pancreatic body lesion. Fine-needle biopsy and immunohistochemistry of the pancreatic lesion confirmed neuroendocrine tumor, while the mesenteric lymph node was found to be benign. The patient underwent robotic-assisted ileocolic resection and has ongoing surveillance of the pancreatic lesion. Conclusion: Terminal ileitis encompasses a host of pathologic processes, including inflammatory states, infectious disease, malignancy, and vasculitis. Importantly, small bowel cancer is an increasing cause of terminal ileitis. Screening colonoscopy with ileal intubation can be a valuable tool for early detection of these lesions.

A complicated case of terminal ileitis post-COVID-19 infection requiring bowel resection

Since the beginning of the COVID-19 pandemic, there have been reports of children developing systemic hyperinflammatory response to COVID-19 infection, known as Paediatric Inflammatory Multisystem Syndrome Temporally associated with SARS-COV-2 (PIMS-TS). Here we would like to discuss a case of a 15-year-old male with PIMS-TS presenting as complicated terminal ileitis, requiring ileocaecal resection. Histopathologic findings of the ileocaecal specimen revealed thickened bowel mucosa, with features of granulomatous inflammation similar to Crohn’s disease, without features of intestinal vasculitis or viral particles. His post-operative course was complicated by fresh rectal bleeding, requiring urgent blood transfusion and endoscopy. Source of bleeding was not identified and his bleeding self-resolved. Gut biopsies of the remaining bowel taken during endoscopy were normal. Although this case suggests that the inflammatory process is focal to the terminal ileum with a good short-term prognosis, further follow-up is required to assess for long-term effects and risks of bowel disease.

The efficacy of mesalazine on nonspecific terminal ileal ulcers: A randomized controlled trial

Background: Nonspecific terminal ileal ulcers are one of the common ulcerative diseases in terminal ileum. However, the studies about treatment efficacy are scarce. We aimed to investigate the efficacy of mesalazine in the treatment of this disease.

Methods: Eighty-two patients with nonspecific terminal ileal ulcers who sought outpatient medical treatment in the Division of Gastroenterology, Wuhan Union Hospital, from April 2016 to January 2019 were enrolled and randomly divided into two groups. The experimental group took mesalazine orally, 4.0 g/d, once a day for 3 months. The control group was followed up without special intervention. The primary endpoint was the endoscopic remission rate at the 6^th and 12^th month. Secondary endpoints included the clinical remission rate at the 1^st, 6^th and 12^th month and adverse events (ChiCTR1900027503).

Results: About the endoscopic efficacy, the remission rate of the experimental group and control group was 73.2 versus 61.0% at the 6^th month (RR = 1.20, 95%CI 0.88∼1.63, p = 0.24) and 87.8 versus 78.0% at the 12^th month (RR = 1.13, 95%CI 0.92∼1.37, p = 0.24). About the clinical efficacy, the remission rate was 70.3 versus 43.8% at the 1^st month (RR = 1.61, 95%CI 1.03∼2.51, p = 0.03), 83.8 versus 68.8% at the 6^th month (RR = 1.22, 95%CI 0.93∼1.60, p = 0.14) and 91.9 versus 81.3% at the 12^th month (RR = 1.13, 95%CI 0.93∼1.37, p = 0.34). During follow-up, no patients were diagnosed with Crohn’s disease or intestinal tuberculosis, and no patients developed significant complications.

Conclusion: For patients with nonspecific terminal ileal ulcers, there is no disease progression over a short term. In addition, there is no significant difference in clinical or endoscopic efficacy between patients who received mesalazine and patients who are followed up without special intervention.

Comprehensive Evaluation and Unique Morphologic Features of Nonsteroidal Anti-Inflammatory Drug (NSAID) Enteropathy in the Terminal Ileum

Differentiating NSAID enteropathy from Crohn disease can be challenging on terminal ileum biopsy. It is important to distinguish these two entities for management. In this study, clinical, radiographic, endoscopic, and histologic features of 30 patients diagnosed with NSAID enteropathy and 30 patients diagnosed with Crohn disease on terminal ileal biopsy were compared. None of the patients in the NSAID cohort demonstrated significant changes on imaging performed prior to biopsy. Depending on disease severity, patients with Crohn disease showed imaging findings ranging from minimal changes to significant bowel wall and/or luminal changes. Endoscopically, erythema, erosions, and/or ulcers in the terminal ileum were observed in a majority of NSAID cases. Patients with active Crohn disease were noted to have erythema, ulcers, strictures, and/or visible inflammation throughout the distal ileum and colon. Histologically, at least 80% of cases in each cohort showed ulceration/erosion and cryptitis/crypt abscesses. The Crohn disease cohort had significantly higher degree of lymphoplasmacytic inflammation in the lamina propria compared to the NSAID cohort. In contrast, a significantly higher percentage of the NSAID cohort had gland/crypt atrophy. A decrease in number of Paneth cells was found in the NSAID cohort. Decreased lamina propria lymphoplasmacytic inflammation was the most specific and the presence of gland atrophy the most sensitive feature favoring NSAID enteropathy. In summary, the combination of gland/crypt/Paneth cell atrophy with decreased lamina propria lymphoplasmacytic inflammation can aid in differentiating NSAID enteropathy from Crohn disease in terminal ileal biopsies; however, correlation with clinical, radiographic, and endoscopic findings is still required.

The value of magnetic resonance enterography in diagnostic difficulties associated with Crohn's disease

Purpose

The diagnosis of Crohn’s disease (CD), one of the inflammatory bowel diseases (IBD), along with ulcerative colitis (UC), is often challenging due to the limitations of small intestine visualisation. Magnetic resonance enterography (MRE) enables imaging of intraluminal and extraintestinal complications without ionizing radiation. The objective of this study is to select CD-related MRE features and determine the feasibility of this technique to indicate a group of patients that should be subjected to more invasive diagnostic procedures.

Material and methods

A total of 131 patients (mean age 25) underwent MRE, 60 of whom had been previously diagnosed with CD and 17 with UC. Additionally, 26 patients with suspected IBD and 28 with other or unknown pathologies were included in the study. Radiological reports of MRE examinations, effectuated using a 1.5-T field strength, were retrospectively analysed regarding radiological features of IBD, such as the following: bowel wall thickening, enhancement, comb sign, stricture, enlarged mesenteric nodes, inflammatory infiltration, and abnormal diffusion restriction in diffusion-weighted imaging. The statistical model was based on machine learning of the Kohonen map, together with univariate and multivariate analysis.

Results

The selected neuron (Neuron 3) incorporated 23 cases of CD, 9 of suspected IBD, 2 patients with UC, and 4 with other pathologies. The statistical analysis identified bowel wall thickening, intestinal stricture, and lymphadenopathy as the 3 MRE findings most associated with Neuron 3 (AUC = 0.919, p = 0.031).

Conclusions

Bowel wall thickening, stricture, and enlarged mesenteric lymph nodes in MRE are independent predictive factors for CD diagnosis; thus, patients presenting these features should undergo further examinations. MRE constitutes a powerful imaging modality in cases of suspected IBD.

Analysis and Follow up of Endoscopy Results in 1099 Patients with Terminal Ileum Lesions

OBJECTIVE

We aim to analyze the diagnostic yield, diagnostic accuracy, and delayed diagnosis of patients with terminal ileum lesions, providing follow-up suggestions for suspected patients.

METHODS

We carried out an analysis of 1099 patients who had terminal ileum lesions in our hospital from 2009 to 2019. The endoscopy reports and histopathology reports of terminal ileal biopsies were recorded. Clinical diagnosis and management were reviewed to determine whether there was a need to correct after a follow-up endoscopy result.

RESULTS

A total of 1099 patients were found to have terminal ileum lesions, among which 959 in 1099 patients (87.26%) were diagnosed as benign, 17 in 1099 patients (1.55%) were diagnosed as malignant, and 123 in 1099 patients (11.19%) were diagnosed as suspected. The diagnostic accuracies of terminal ileal polyp, cyst, cancer, eosinophilic enteritis, parasite, lymphofollicular hyperplasia, and amyloidosis were 100%. The diagnosis was delayed in 9.93% of Crohn's disease (CD) and 12.5% of lymphoma. Among the definite cases, the diagnosis was corrected during the follow-up in 12.5% of the patients, while the clinical treatment was corrected during the follow-up in 17.86% of the patients. Among the suspected cases, the diagnosis and treatment was corrected in 61.11% of the patients during the follow-up.

CONCLUSION

Coincident diagnosis of ileitis and ileum ulcer is low. Delayed diagnosis of Crohn's disease and lymphoma were observed in a certain proportion of patients with terminal ileum lesions. A follow-up endoscopy was strongly recommended for these suspected patients with terminal ileum lesions.

Crohn's disease at radiological imaging: focus on techniques and intestinal tract

Over recent years, inflammatory bowel diseases have become an issue of increased attention in daily clinical practice, due to both a rising incidence and improved imaging capability in detection. In particular, the diagnosis of Crohn's disease is based on clinical picture, laboratory tests and colonoscopy with biopsy. However, colonoscopic evaluation is limited to the mucosal layer. Thus, imaging modalities play a pivotal role in enriching the clinical picture, delivering information on intestinal and extraintestinal involvement. All the imaging modalities can be employed in evaluation of Crohn's disease patients, each of them with specific strengths as well as limitations. In this wide selection, the choice of a proper diagnostic framework can be challenging for the clinician. Therefore, the aim of this work is to offer an overview of the different imaging techniques, with brief technical details and diagnostic potential related to each intestinal tract.

Daily Dilemmas in Pediatric Gastrointestinal Pathology

The evaluation of gastrointestinal pathology in children often requires a different approach from that in adults. In this concise review, the authors outline 3 diagnostic challenges that are often encountered in daily practice; these include eosinophilic diseases, duodenal intraepithelial lymphocytosis with preserved villous architecture, and terminal ileal inflammation in the setting of idiopathic inflammatory bowel disease.

Perforated Meckel Diverticulum: A Rare Cause of Acute Abdomen in Children

Meckel diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract and the most common cause of gastrointestinal bleeding in children. Although it usually follows the rule of 2's, exceptions to this rule are reported in the literature. Often asymptomatic, MD is commonly an incidental finding during surgical interventions. When symptomatic, the most common presentation of this condition is painless rectal bleeding. A myriad of other nonspecific symptoms are however possible, especially in adults, thus making this diagnosis difficult. Meckel diverticulum has been reported to mimic other abdominal pathologies like appendicitis, inflammatory bowel disease, and pancreatitis to name a few.We report a patient with acute abdomen in whom the more common causes of acute abdomen were ruled out and a diagnosis of MD was established on exploratory laparoscopy, only after he developed perforation. This report emphasizes the need for maintaining a high index of suspicion towards a possibility of a complicated MD in patients presenting with an acute abdomen, once other causes of acute abdomen are ruled out.

Environmental Microbial Factors Determine the Pattern of Inflammatory Lesions in a Murine Model of Crohn's Disease-Like Inflammation

Crohn's disease (CD) patients can be grouped into patients suffering from ileitis, ileocolitis, jejunoileitis, and colitis. The pathophysiological mechanism underlying this regional inflammation is still unknown. Although most murine models of inflammatory bowel disease (IBD) develop inflammation in the colon, there is an unmet need for novel models that recapitulate the spontaneous and fluctuating nature of inflammation as seen in CD. Recently, mice with an intestinal epithelial cell-specific deletion for Caspase-8 (Casp8ΔIEC mice), which are characterized by cell death-driven ileitis and disrupted Paneth cell homeostasis, have been identified as a novel model of CD-like ileitis. Here we uncovered that genetic susceptibility alone is sufficient to drive ileitis in Casp8ΔIEC mice. In sharp contrast, environmental factors, such as a disease-relevant microbial flora, determine colonic inflammation. Accordingly, depending on the microbial environment, isogenic Casp8ΔIEC mice either exclusively developed ileitis or suffered from pathologies in several parts of the gastrointestinal tract. Colitis in these mice was characterized by massive epithelial cell death, leading to spread of commensal gut microbes to the extra-intestinal space and hence an aberrant activation of the systemic immunity. We further uncovered that Casp8ΔIEC mice show qualitative and quantitative changes in the intestinal microbiome associated with an altered mucosal and systemic immune response. In summary, we identified that inflammation in this murine model of CD-like inflammation is characterized by an immune reaction, presumably directed against a disease-relevant microbiota in a genetically susceptible host, with impaired mucosal barrier function and bacterial clearance at the epithelial interface.

Interferon Lambda Promotes Paneth Cell Death Via STAT1 Signaling in Mice and Is Increased in Inflamed Ileal Tissues of Patients With Crohn's Disease

BACKGROUND & AIMS

Interferon lambda (IFNL) is expressed at high levels by intestinal epithelial cells (IECs) and mucosal immune cells in response to infection and inflammation. We investigated whether IFNL might contribute to pathogenesis of Crohn's disease (CD).

METHODS

We obtained serum samples and terminal ileum biopsies from 47 patients with CD and 16 healthy individuals (controls). We measured levels of IFNL by enzyme-linked immunosorbent assay and immunohistochemistry and location of expression by confocal microscopy. Activation of IFNL signaling via STAT1 was measured in areas of no, mild, moderate, and severe inflammation and correlated with Paneth cell homeostasis and inflammation. IFNL expression and function were studied in wild-type mice and mice with intestinal epithelial cell-specific (ΔIEC) disruption or full-body disruption of specific genes (Mlkl^-/-, Stat1^ΔIEC, Casp8^ΔIEC, Casp8^ΔIECRipk3^-/-, Casp8^ΔIECTnfr^-/-, Casp8^ΔIECMlkl^-/-, and Nod2^-/- mice). Some mice were given tail vein injections of a vector encoding a secreted form of IFNL. Intestinal tissues were collected from mice and analyzed by immunohistochemistry and immunoblots. We generated 3-dimensional small intestinal organoids from mice and studied the effects of IFNL and inhibitors of STAT-signaling pathway.

RESULTS

Patients with CD had significant increases in serum and ileal levels of IFNL compared with controls. Levels of IFNL were highest in ileum tissues with severe inflammation. High levels of IFNL associated with a reduced number of Paneth cells and increased cell death at the crypt bottom in inflamed ileum samples. Intestinal tissues from the ileum of wild-type mice injected with a vector expressing IFNL had reduced numbers of Paneth cells. IFNL-induced death of Paneth cells in mice did not occur via apoptosis, but required Mixed Lineage Kinase Domain Like (MLKL) and activation of Signal transducer and activator of transcription 1 (STAT1). In organoids, inhibitors of Janus kinase (JAK) signaling via STAT1 (glucocorticoids, tofacitinib, or filgotinib) reduced expression of proteins that mediate cell death and prevented Paneth cell death.

CONCLUSIONS

Levels of IFNL are increased in serum and inflamed ileal tissues from patients with CD and associated with a loss of Paneth cells. Expression of a secreted form of IFNL in mice results in loss of Paneth cells from intestinal tissues, via STAT1 and MLKL, controlled by caspase 8. Strategies to reduce IFNL or block its effects might be developed for treatment of patients with CD affecting the terminal ileum.

Pyloric and foveolar type metaplasia are important diagnostic features in Crohn's disease that are frequently missed in routine pathology

Pyloric type metaplasia (PYME) as evidence of chronic mucosal damage, is one of the main histopathological findings for diagnosing Crohn's Disease (CD) in terminal ileum biopsies, according to the latest guidelines but still frequently underdiagnosed in routine pathology. Foveolar metaplasia (FOME) changes in mucosa, another aspect of the chronic post -inflammatory Ulcer Associated Cell Lineage (UACL), have only been reported in a few cases. However, their clinical significance has not been investigated in depth except in pouchitis. The aim of this study was to investigate the importance of meticulous study of terminal ileum biopsies for the recognition of PYME/FOME as an adjunct finding helpful for the diagnosis of CD. In the present study, two experienced gastrointestinal pathologists, have reviewed 105 terminal ileum biopsies from 105 patients with CD, using a protocol of 15 sections on average per biopsy. In 21% (22/105) of cases PYME was recognized and in 4% (4/105) FOME was also present. PYME/FOME had not been detected in 83% of these cases in the original reports. FOME was also identified in terminal ileum biopsies, a feature not reported previously in CD. Conclusively, PYME/FOME can be easily missed in terminal ileum biopsies from patients with suspected or known CD unless a meticulous study of the histologic material is carried out combined with awareness of the pathologist about its importance.

Backwash ileitis in ulcerative colitis: Are there MR enterographic features that distinguish it from Crohn disease?

OBJECTIVE

To reveal the MR enterography (MRE) findings that distinguish backwash ileitis (BWI) from terminal ileitis due to Crohn's disease (CD) and to determine the usability of barium studies manifestations (ileocecal valve (ICV) gaping, terminal ileum dilatation) in MRE for the diagnosis of BWI in ulcerative colitis (UC) patients by pointing at the diagnostic performance of these imaging findings.

SUBJECTS-METHODS

The study population consisted of patients who were diagnosed as ulcerative colitis (UC), and underwent 1.5 T MRI between August 2011 and November 2017 to rule out small bowel involvement. The matched controls were comprised of Crohn's patients examined at the same period. Ileocolonoscopic/ histopathologic findings were accepted as reference standard. Mural/extramural changes in bowel segments, ileocecal valve (ICV) gaping, terminal ileum dilatation, restricted diffusion and anatomical extent of involvement were evaluated. In UC patients, the association between ICV gaping and terminal ileum dilatation and BWI was assessed by χ2 test. The diagnostic accuracy of these two findings in BWI was determined.

RESULTS

Sixty patients were included in the study (30 UC; 30 CD; mean age, 43 years in both groups). Ileocecal valve gaping and terminal ileum dilatation were significantly more frequent among BWI patients (p < 0.001) in UC. Patients with BWI showed a higher rate of pancolitis (88.9%). Median terminal ileum wall thickness was found to be significantly greater in patients with CD (p < 0.001).

CONCLUSION

In patients with definite diagnosis of UC, ileocecal valve gaping and terminal ileum dilatation suggest the development of BWI. However, these findings cannot be use to differentiate cause of terminal ileitis in patients with unconfirmed diagnosis and do not give reliable information about the causative factor of ileitis.

Community-acquired infection to Raoultella ornithinolytica presenting as appendicitis and shock in a healthy individual

Raoultella ornithinolytica and Raoultella planticola are histamine-producing bacteria that are usually found in fish and water. They are associated with scombroid syndrome that presents with vomiting and flushing. A wide range of infections with these germs is reported, but mainly in fragile hospitalized patients with multiple comorbidities. We report the case of a 54-year-old healthy patient who presented with 24-hours abdominal pain, vomiting, flushing and shock. The abdominal examination showed guarding in the right lower quadrant (RLQ), and the abdominal CT scan images showed a thickened terminal ileum and a distended appendix. The patient underwent a surgical exploration revealing a normal terminal ileum but an inflamed appendicular base. Raoultella ornithinolytica was found in blood cultures and in the liquid retrieved from the RLQ. To the best of our knowledge, this is the first report of a severe life-threatening intra-abdominal presentation due to a community-acquired R. ornithinolytica infection.

Associations between inflammatory bowel diseases and vitamin D

Inflammatory Bowel Diseases (IBD) are increasing sharply, and the common medications are not effective for most patients. Vitamin D (VD) has been considerate to reduce inflammatory processes and may be helpful in IBD. The aim of this review was to perform an update on the potential role of VD in the IBD. We performed a search for articles associating VD and IBD published in MEDLINE-PubMed and EMBASE. The focused question used for the search was "What is the association between Inflammatory Bowel Disease and Vitamin D?" The exclusion criteria for this search were studies not in English, editorials, case reports, or poster presentations. VD prevents the inflammatory process such as negatively interfering with the release of Interleukin (IL)-1, IL-6, and Tumour Necrosis Factor-α; enhancing the function of the intestinal epithelial barrier; decreasing the occurrence of apoptosis; stimulating Toll-Like Receptor-4; inducing the production of an antimicrobial peptide in Paneth cells. Furthermore, deficiency of VD is related to the severity of the symptoms and increased the risk of cancer and surgery. In conclusion, VD shows a potential role in the management of IBD, the supplementation is inexpensive, safe, and leads to improvement of the quality of life.

Pyloric Gland Metaplasia of the Ileocecal Valve: Clinicopathologic Correlates of Inflammatory Bowel Disease

Pyloric gland metaplasia of the ileocecal valve, in the setting of Crohn's disease, is an unusual clinical entity. Though its etiology and pathogenesis remains unclear, metaplastic changes have been associated with chronic inflammation and inflammatory bowel disease. Herein, we report a case of a 23-year-old male who presented for surveillance colonoscopy after being diagnosed with Crohn's disease four years ago. Diagnostic colonoscopy revealed stenosis of the ileocecal valve as well as a 5 mm polypoid circumferential non-obstructing lesion. Excisional biopsy followed by histopathology revealed pyloric metaplasia and non-necrotizing epithelioid cell granuloma. We discuss the clinical significance of pyloric gland metaplasia of the ileocecal valve in the context of inflammatory bowel disease.