Quantity and distribution of eosinophils in the gastrointestinal tract of children

Histopathology of Eosinophilic Gastrointestinal Diseases Beyond Eosinophilic Esophagitis

Eosinophilic gastrointestinal diseases (EGID), such as eosinophilic gastritis (EoG), eosinophilic enteritis, and eosinophilic colitis (EoC), are chronic inflammatory conditions characterized by persistent gastrointestinal symptoms and elevated levels of activated eosinophils in the gastrointestinal tract. EoG and eosinophilic duodenitis (EoD) are strongly associated with food allergen triggers and TH2 inflammation, whereas EoC shows minimal transcriptomic overlap with other EGIDs. The level of expression of certain genes associated with TH2 immune response is associated with certain histopathologic findings of EoG, EoD, and EoC. Current immune therapy for EoG depletes tissue eosinophilia with persistence of other histopathologic features of disease.

The Dual Lens of Endoscopy and Histology in the Diagnosis and Management of Eosinophilic Gastrointestinal Disorders-A Comprehensive Review

Eosinophilic Gastrointestinal Disorders (EGIDs) are a group of conditions characterized by abnormal eosinophil accumulation in the gastrointestinal tract. Among these EGIDs, Eosinophilic Esophagitis (EoE) is the most well documented, while less is known about Eosinophilic Gastritis (EoG), Eosinophilic Enteritis (EoN), and Eosinophilic Colitis (EoC). The role of endoscopy in EGIDs is pivotal, with applications in diagnosis, disease monitoring, and therapeutic intervention. In EoE, the endoscopic reference score (EREFS) has been shown to be accurate in raising diagnostic suspicion and effective in monitoring therapeutic responses. Additionally, endoscopic dilation is the first-line treatment for esophageal strictures. For EoG and EoN, while the literature is more limited, common endoscopic findings include erythema, nodules, and ulcerations. Histology remains the gold standard for diagnosing EGIDs, as it quantifies eosinophilic infiltration. In recent years, there have been significant advancements in the histological understanding of EoE, leading to the development of diagnostic scores and the identification of specific microscopic features associated with the disease. However, for EoG, EoN, and EoC, precise eosinophil count thresholds for diagnosis have not yet been established. This review aims to elucidate the role of endoscopy and histology in the diagnosis and management of the three main EGIDs and to analyze their strengths and limitations, their interconnection, and future research directions.

[Eosinophils in otorhinolaryngology: friend or foe?]

This article summarizes the essential aspects of current knowledge about eosinophils, classifies eosinophilia in terms of the dimensions healthy or harmful reaction, takes a specific look at eosinophils in the field of otorhinolaryngology, and gives recommendations for diagnostic workup and therapeutic intervention in case of proven eosinophilia, particularly as an adverse drug reaction. The thoughts are inspired by communications at the 29th Congress of the European Rhinologic Society in Sofia, Bulgaria, 2023.

Nutrient-derived signals regulate eosinophil adaptation to the small intestine

Eosinophils are well recognized as effector cells of type 2 immunity, yet they also accumulate in many tissues under homeostatic conditions. However, the processes that govern homeostatic eosinophil accumulation and tissue-specific adaptation, and their functional significance, remain poorly defined. Here, we investigated how eosinophils adapt to the small intestine (SI) microenvironment and the local signals that regulate this process. We observed that eosinophils gradually migrate along the crypt-villus axis, giving rise to a villus-resident subpopulation with a distinct transcriptional signature. Retinoic acid signaling was specifically required for maintenance of this subpopulation, while IL-5 was largely dispensable outside of its canonical role in eosinophil production. Surprisingly, we found that a high-protein diet suppressed the accumulation of villus-resident eosinophils. Purified amino acids were sufficient for this effect, which was a consequence of accelerated eosinophil turnover within the tissue microenvironment and was not due to altered development in the bone marrow. Our study provides insight into the process of eosinophil adaptation to the SI, highlighting its reliance on nutrient-derived signals.

Joint ESPGHAN/NASPGHAN Guidelines on Childhood Eosinophilic Gastrointestinal Disorders Beyond Eosinophilic Esophagitis

INTRODUCTION

Eosinophilic gastrointestinal disorders beyond eosinophilic esophagitis (non-EoE EGIDs) are rare chronic inflammatory disorders of the gastrointestinal (GI) tract. Diagnosis is based on clinical symptoms and histologic findings of eosinophilic inflammation after exclusion of a secondary cause or systemic disease. Currently, no guidelines exist for the evaluation of non-EoE EGIDs. Therefore, the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) formed a task force group to provide consensus guidelines for childhood non-EoE EGIDs.

METHODS

The working group was composed of pediatric gastroenterologists, adult gastroenterologists, allergists/immunologists, and pathologists. An extensive electronic literature search of the MEDLINE, EMBASE, and Cochrane databases was conducted up to February 2022. General methodology was used in the formulation of recommendations according to the Appraisal of Guidelines for Research and Evaluation (AGREE) II and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to meet current standards of evidence assessment.

RESULTS

The guidelines provide information on the current concept of non-EoE EGIDs, disease pathogenesis, epidemiology, clinical manifestations, diagnostic and disease surveillance procedures, and current treatment options. Thirty-four statements based on available evidence and 41 recommendations based on expert opinion and best clinical practices were developed.

CONCLUSION

Non-EoE EGIDs literature is limited in scope and depth, making clear recommendations difficult. These consensus-based clinical practice guidelines are intended to assist clinicians caring for children affected by non-EoE EGIDs and to facilitate high-quality randomized controlled trials of various treatment modalities using standardized, uniform disease definitions.

Determination of Optimal Eosinophil Thresholds for Diagnosis of Eosinophilic Gastritis and Duodenitis: A Pooled Analysis of 4 Prospective Studies

INTRODUCTION

Consensus is lacking regarding the number of eosinophils (eos) required for the diagnosis of eosinophilic gastritis (EoG) and eosinophilic duodenitis (EoD). In addition, thresholds that require multiple high-power fields (HPFs) may not be practical for clinical use, resulting in delayed or missed diagnoses. This pooled analysis of 4 prospective studies assessed thresholds for multiple and single HPFs used to diagnose EoG and EoD.

METHODS

Studies included the phase 2 ENIGMA1, the phase 3 ENIGMA2, an EoG/EoD prevalence study and a healthy volunteer study. Eos were quantified in the epithelium and lamina propria for controls and symptomatic participants. Symptomatic participants were further divided by histologic diagnosis of EoG/EoD. Peak eos counts were assessed, and the area under the receiver operating characteristic curve was analyzed to identify eos cutoffs for detection of EoG/EoD using the Youden index and sensitivity and specificity equality approaches.

RESULTS

Based on the highest specificity analysis in 740 patients, the optimal eos threshold was determined to be 20 eos/HPF in 5 gastric HPFs for EoG (71% sensitivity and 94% specificity) and 33 eos/HPF in 3 duodenal HPFs for EoD (49% sensitivity and 100% specificity). For single-field analysis, the optimal eos thresholds were 33 eos/HPF (EoG) and 37 eos/HPF (EoD), both corresponding to 93% sensitivity and 93% specificity.

DISCUSSION

Highly specific single gastric and duodenal HPF thresholds may have more clinical applicability than thresholds requiring multiple HPFs and could better facilitate development of practical histopathologic guidelines to aid pathologists and clinicians in the detection and diagnosis of EoG and/or EoD.

Neuromedin U programs eosinophils to promote mucosal immunity of the small intestine

Eosinophils are granulocytes that play an essential role in type 2 immunity and regulate multiple homeostatic processes in the small intestine (SI). However, the signals that regulate eosinophil activity in the SI at steady state remain poorly understood. Through transcriptome profiling of eosinophils from various mouse tissues, we found that a subset of SI eosinophils expressed neuromedin U (NMU) receptor 1 (NMUR1). Fate-mapping analyses showed that NMUR1 expression in SI eosinophils was programmed by the local microenvironment and further enhanced by inflammation. Genetic perturbation and eosinophil-organoid coculture experiments revealed that NMU-mediated eosinophil activation promotes goblet cell differentiation. Thus, NMU regulates epithelial cell differentiation and barrier immunity by stimulating NMUR1-expressing eosinophils in the SI, which highlights the importance of neuroimmune-epithelial cross-talk in maintaining tissue homeostasis.

A Marked Eosinophilic Infiltration in Mucosa Could Be a Better Predictive Factor for Intractable Non-Esophageal Eosinophilic Gastrointestinal Disorders

INTRODUCTION

Non-esophageal eosinophilic gastrointestinal disorders (non-EoE EGIDs) are rare, but their prevalence has recently increased. Although it has been reported that one-half of patients with non-EoE EGIDs have intractable clinical courses, their clinical features are not fully understood.

METHODS

This is a multicenter retrospective study in which 10 institutions in Japan participated. Clinical databases from January 1998 to December 2020 were reviewed to identify patients with non-EoE EGIDs. A total of 44 patients were identified; they were divided into two groups based on their clinical course: an intractable group and a non-intractable group. The clinical features were compared between the two groups by a logistic regression analysis. Remarkable eosinophilic infiltration (REI) was defined histologically when the maximal counts of mucosal eosinophils reached a threshold level in the respective area of biopsy.

RESULTS

Prevalence of drug allergy and eosinophil counts more than 500/μL (EOS), vomiting symptoms, abnormalities of the stomach, duodenum, and jejunum on computed tomography (upper gastrointestinal abnormality on computed tomography [UACT]), and REI were significantly different between the two groups. Among the factors that were potentially associated with an intractable clinical course, logistic regression revealed that REI, EOS, and UACT were significant factors. Based on an analysis of the area under the receiver operator characteristic curve, a combination of REI and EOS had the lowest Akaike's information criterion, indicating the best model to predict an intractable clinical course.

CONCLUSIONS

REI may predict an intractable course in patients with non-EoE EGIDs. In addition, the combination of REI and EOS was a better predictor than REI alone.

Molecular analysis of duodenal eosinophilia

BACKGROUND

Eosinophilic duodenitis (EoD), characterized by nonspecific gastrointestinal symptoms and increased numbers of duodenal eosinophils, may be in the eosinophilic gastrointestinal disease spectrum. However, diagnostic thresholds and pathogenic processes of duodenal tissue eosinophilia are inadequately characterized.

OBJECTIVE

We aimed to define an EoD transcriptome and pathologic pathways.

METHODS

RNA sequencing and histologic features of human duodenal biopsy samples were analyzed as a function of duodenal eosinophils levels. For analyses, we defined EoD as more than 52 peak eosinophils/hpf (n = 8), duodenal eosinophilia as 30 to 52 eosinophils/hpf (n = 11), and normal controls as fewer than 30 eosinophils/hpf (n = 8). Associations between gene expression and histologic features were analyzed with Spearman correlation.

RESULTS

We identified 382 differentially expressed genes (EoD transcriptome) between EoD and normal controls (>2-fold change [adjusted P < .05]). The EoD transcriptome distinguished EoD from controls (duodenal eosinophilia and normal controls). The duodenal eosinophil count was correlated with a distinct EoD transcriptome when 50 to 60 peak eosinophils/hpf were present. The EoD transcriptome was enriched in genes involved in IL-4/IL-13 signaling, mast cells, and myeloid progenitor cells. Among duodenal histologic features, lamina propria eosinophil sheets was the most associated with transcriptomic changes (r = 0.66; P < .01). EoD gene signatures were shared with eosinophilic esophagitis and eosinophilic gastritis but not with eosinophilic colitis or celiac disease.

CONCLUSION

We have identified an EoD transcriptomic signature that emerges at 50 to 60 peak eosinophils/hpf and established EoD as part of a spectrum of upper eosinophilic gastrointestinal disorder associated with type 2 immunity and distinct from eosinophilic colitis and celiac disease. These findings provide a basis for improving diagnosis and treatment.

Number and distribution of eosinophils and lymphocytes in the Japanese pediatric gastrointestinal tract: in search of a definition for "abnormally increased eosinophils"

BACKGROUND

Primary eosinophilic gastrointestinal disorders (EGIDs) constitute chronic allergic inflammation. The number of eosinophils is one of the diagnostic criteria; more than 20 eosinophils per high-power field (HPF) in the gastrointestinal (GI) tract are considered abnormal in Japan. However, the quantity of eosinophils considered normal varies according to anatomical location and geographical region; such values have not been reported in Japanese pediatric patients, nor have the numbers of lymphocytes in the normal pediatric stomach. To establish a reference for defining diagnostic criteria for EGIDs, we evaluated the number of eosinophils in the normal Japanese pediatric GI tract.

METHODS

We examined 131 biopsy cases without significant clinical history, endoscopic abnormality, or histological abnormality. Immunohistochemical analysis of CD3 and CD20 was performed.

RESULTS

The mean eosinophil density was highest in the cecum (49.5 ± 22.4 per HPF). Counts of more than 20 eosinophils per HPF were observed in the duodenum [bulb (20.0 ± 9.6) and second portion (30.0 ± 15.8)], terminal ileum (38.3 ± 22.7), cecum (49.5 ± 22.4), ascending colon (42.3 ± 25.3), transverse colon (29.4 ± 17.0), and descending colon (32.2 ± 17.9). Counts of fewer than 10 eosinophils per HPF were observed in the stomach and rectum; a count of fewer than one eosinophil per HPF was observed in the esophagus. More than 100 CD3-positive T cells per HPF were observed in the stomach.

CONCLUSIONS

The mean numbers of eosinophils in the bowel were greater than 20 per HPF. For Japanese pediatrics, the current threshold eosinophil count should be revised.

Eosinophilic Gastrointestinal Diseases: The Pathogenesis, Diagnosis, and Treatment

Eosinophilic gastrointestinal diseases are delayed-type chronic allergic disorders that show gastrointestinal eosinophil dense infiltration, with an exaggerated Th2-type immune reaction considered to be an important mechanism. These diseases can be roughly divided into two types: eosinophilic esophagitis, mainly found in young and middle-aged men, and eosinophilic gastroenteritis, which is found in both genders equally. A diagnosis of eosinophilic esophagitis is suspected when characteristic endoscopic findings, including longitudinal furrows and rings, are noted. However, characteristic endoscopic abnormalities are rarely found in cases with eosinophilic gastroenteritis, so multiple biopsy sampling from the apparently normal gastrointestinal mucosal surface is important for making an accurate diagnosis. The administration of systemic glucocorticoid is the standard treatment for eosinophilic gastroenteritis, while acid inhibitors and topical glucocorticoid swallowing therapy are effective for eosinophilic esophagitis. Anti-cytokine therapies for eosinophilic gastrointestinal diseases are currently under development.

Breaking down the complex pathophysiology of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic and progressive immune-mediated disease of the esophagus associated with antigen-driven type 2 inflammation and symptoms of esophageal dysfunction. Our understanding of EoE pathophysiology has evolved since its initial recognition more than 20 years ago and has translated into diagnostic and novel therapeutic approaches that are affecting patient care. The mechanisms underlying disease development and progression are influenced by diverse factors, such as genetics, age, allergic comorbidities, and allergen exposures. Central to EoE pathophysiology is a dysregulated feed-forward cycle that develops between the esophageal epithelium and the immune system. Allergen-induced, type 2-biased immune activation by the esophageal epithelium propagates a cycle of impaired mucosal barrier integrity and allergic inflammation, eventually leading to tissue remodeling and progressive organ dysfunction. Herein, we review the current understanding of fundamental pathophysiological mechanisms contributing to EoE pathogenesis.

The Relationship between Eosinophil Density in the Colonic Mucosa and Eosinophil Blood Count in Children: A Cross-Sectional Study

Eosinophils are found in the mucosa of the healthy gastrointestinal tract, but they also often accompany gastrointestinal diseases. We hypothesized that a positive correlation exists between blood eosinophil count and colonic eosinophil mucosal density in children. Electronic health records regarding 181 colonoscopies, performed with biopsy in the years 2019-2022, were screened for information on blood and colonic eosinophil count, age, sex, diagnoses, weight, height, white blood cell (WBC) count, serum C-reactive protein (CRP), and total IgE concentration. The median age (IQR) of the 107 included children (109 colonoscopies) was 12.4 years (8.1-15.5); 32 presented with blood eosinophilia (29.3%). The median eosinophil density/high-power field in the colonic mucosa was 22.5 (9-31). We found a weak correlation between colonic mucosal eosinophil density and blood eosinophil count (r = 0.295, 95% CI 0.108-0.462, p = 0.0018). This association was more pronounced in patients with elevated CRP (r = 0.529, 95% CI 0.167-0.766, p = 0.0054) and older than 12.4 years (r = 0.448, 95% CI 0.197-0.644, p = 0.00068). Peripheral blood eosinophilia might hint at increased mucosal colonic eosinophil density, especially in older children and in the presence of systemic inflammation. However, it seems unlikely that blood and colonic eosinophilia are strongly linked in younger children. Studies in adults are warranted.

IL-22BP production is heterogeneously distributed in Crohn’s disease

Crohn’s disease (CD), a form of inflammatory bowel disease (IBD), is characterized by impaired epithelial barrier functions and dysregulated mucosal immune responses. IL-22 binding protein (IL-22BP) is a soluble inhibitor regulating IL-22 bioactivity, a cytokine proposed to play protective roles during CD. We and others have shown that IL-22BP is produced in IBD inflamed tissues, hence suggesting a role in CD. In this work, we extended the characterization of IL-22BP production and distribution in CD tissues by applying enzyme-linked immunosorbent assays to supernatants obtained from the culture of endoscopic biopsies of patients, and reverse transcription-quantitative polymerase chain reaction on sorted immune cell subsets. We reveal that IL-22BP levels are higher in inflamed ileums than colons. We observe that in a cell-intrinsic fashion, populations of mononuclear phagocytes and eosinophils express IL-22BP at the highest levels in comparison to other sources of T cells. We suggest the enrichment of intestinal eosinophils could explain higher IL-22BP levels in the ileum. In inflamed colon, we reveal the presence of increased IL-22/IL22BP ratios compared to controls, and a strong correlation between IL-22BP and CCL24. We identify monocyte-derived dendritic cells (moDC) as a cellular subtype co-expressing both cytokines and validate our finding using in vitro culture systems. We also show that retinoic acid induces the secretion of both IL-22BP and CCL24 by moDC. Finally, we report on higher IL-22BP levels in active smokers. In conclusion, our work provides new information relevant to therapeutic strategies modulating IL-22 bioactivity in CD, especially in the context of disease location.

Duodenal Eosinophils and Mast Cells in Functional Dyspepsia: A Systematic Review and Meta-Analysis of Case-Control Studies

BACKGROUND & AIMS

This study explored the link between duodenal eosinophils and mast cells in patients with functional dyspepsia (FD).

METHODS

MEDLINE (PubMed) and Embase electronic databases were searched until June 2021 for case-control studies reporting duodenal eosinophils and mast cells in FD. Pooled standardized mean difference (SMD), odds ratio, and 95% CIs of duodenal eosinophils and mast cells in FD patients and controls were calculated, using a random-effects model.

RESULTS

Twenty-two case-control studies with 1108 FD patients and 893 controls were identified. Duodenal eosinophils (SMD, 1.29; 95% CI, 0.85-1.73; P = .0001) and mast cells (SMD, 2.11; 95% CI, 1.14-3.07; P = .0001) were increased in FD patients compared with controls. Substantial heterogeneity was found (I² = 93.61, P = .0001; and I² = 96.69, P = .0001, respectively) and visual inspection of funnel plots confirmed publication bias. Degranulation of duodenal eosinophils was significantly higher in FD patients compared with controls (odds ratio, 3.78; 95% CI, 6.76-4.48; P = .0001), without statistically significant heterogeneity. We conducted a sensitivity analysis for duodenal eosinophils, by including only high-quality studies, and the results remained unchanged (SMD, 1.73; 95% CI, 1.06-2.40; P = .0001), with substantial heterogeneity. Postinfectious FD patients had increased duodenal eosinophils compared with controls (SMD, 3.91; 95% CI, 1.32-6.51; P = .001) and FD patients without any history of infection (SMD, 1.42; 95% CI, 0.88-1.96; P = .001). Helicobacter pylori-negative FD patients had significantly higher duodenal eosinophils compared with controls (SMD, 3.98; 95% CI, 2.13-5.84; P = .0001), with substantial heterogeneity. No significant difference in duodenal eosinophils was seen according to FD subtypes.

CONCLUSIONS

This meta-analysis suggests a link between duodenal microinflammation and FD. However, the quality of evidence is very low, largely owing to the unexplained heterogeneity and serious risk of publication bias in all comparative analyses. Thus, causality remains uncertain and further studies are required.

The Clinical Significance of Eosinophils in Ulcerative Colitis: A Systematic Review

BACKGROUND AND AIMS

Ulcerative colitis [UC] is characterised by an unpredictable disease course and variable response to therapy. Recent studies suggest a role for eosinophils in both pathogenesis and predicting treatment response. The goal of this study was to determine the association between eosinophils and clinical outcomes in UC.

METHODS

A systematic review of the literature from database inception to May 2021 was performed to identify all studies evaluating the relationship between eosinophils and/or eosinophil-derived proteins [EDPs] and clinical outcomes, such as disease activity, clinical relapse, severity of disease, and response to treatment.

RESULTS

A total of 55 studies were identified. Of these, 34 studies evaluated the relationship between eosinophils in colonic tissue and outcomes and 15 in blood. Eighteen studies assessed the relationship between EDPs and outcomes. In 25 of 34 studies, a positive correlation between eosinophils and/or EDPs and disease activity was reported, three studies found a negative correlation, and nine studies found no correlation. Positive correlations between eosinophils and clinical relapse were shown in four of nine studies, and with disease outcome severity in five of seven studies. Four of 15 studies showed that subjects with higher eosinophil levels had a poor response to treatment.

CONCLUSIONS

These findings suggest that higher eosinophil levels may be associated with increased disease activity and poorer clinical outcomes and response to therapy. Future studies are needed to determine whether a distinct eosinophil-rich UC phenotype exists and whether eosinophil-targeted therapy can alter the disease course.

Potent CCR3 Receptor Antagonist, SB328437, Suppresses Colonic Eosinophil Chemotaxis and Inflammation in the Winnie Murine Model of Spontaneous Chronic Colitis

Eosinophils and their regulatory molecules have been associated with chronic intestinal inflammation and gastrointestinal dysfunctions; eosinophil accumulation in the gut is prominent in inflammatory bowel disease (IBD). The chemokine receptor CCR3 plays a pivotal role in local and systemic recruitment and activation of eosinophils. In this study, we targeted CCR3-ligand interactions with a potent CCR3 receptor antagonist, SB328437, to alleviate eosinophil-associated immunological responses in the Winnie model of spontaneous chronic colitis. Winnie and C57BL/6 mice were treated with SB328437 or vehicle. Clinical and histopathological parameters of chronic colitis were assessed. Flow cytometry was performed to discern changes in colonic, splenic, circulatory, and bone marrow-derived leukocytes. Changes to the serum levels of eosinophil-associated chemokines and cytokines were measured using BioPlex. Inhibition of CCR3 receptors with SB328437 attenuated disease activity and gross morphological damage to the inflamed intestines and reduced eosinophils and their regulatory molecules in the inflamed colon and circulation. SB328437 had no effect on eosinophils and their progenitor cells in the spleen and bone marrow. This study demonstrates that targeting eosinophils via the CCR3 axis has anti-inflammatory effects in the inflamed intestine, and also contributes to understanding the role of eosinophils as potential end-point targets for IBD treatment.

Clinical, histopathological features and efficacy of elimination diet and proton-pump inhibitor therapy in achieving histological remission in Asian children with eosinophilic gastritis

AIM

Paediatric eosinophilic gastritis (EG) is a rare disorder and existing literature on diagnostic criteria and management remains lacking. We aim to describe the clinical spectrum and assess the efficacy of dietary elimination and proton-pump inhibitor (PPI) therapy, with particular emphasis on histologic remission in children with primary EG.

METHODS

We performed a retrospective study of patients aged 0-18 years diagnosed with EG at a single centre in Singapore from 2013 to 2021. EG was diagnosed based on histological criteria of infiltration of >30 eosinophils per high-power film (HPF) in >5 separate HPFs from gastric biopsies, in the absence of other causes. First-line treatment consisted of PPI therapy and empiric 1-6 food elimination diet (FED). Outcomes measured were clinical, endoscopic and histological remission (defined as eosinophil count <20/HPF in gastric biopsies).

RESULTS

Twenty-one (66.7% females) patients were included with median age at diagnosis of 15 months (range:3-192). Majority presented with vomiting (76.2%) and gastrointestinal bleeding (71.4%). Twenty patients were initiated on FED+PPI and 16 had post-treatment biopsies. Clinical, endoscopic and histologic remissions were achieved in 94.7%, 81.3% and 68.8% respectively following FED+PPI. Histologic remission was significantly associated with younger age (9 vs. 132 months; P = 0.026). Four patients who did not respond to FED+PPI were started on oral viscous budesonide, of whom one achieved histological remission and two had clinical improvement.

CONCLUSIONS

FED+PPI is effective as first-line treatment in achieving histological remission in paediatric EG particularly in younger patients. Topical corticosteroids can be considered for those who have failed FED+PPI therapy.

Type-2 Cytokines Promote the Secretion of the Eosinophil–Attractant CCL26 by Intestinal Epithelial Cells in Food-Sensitized Patients

Several inflammatory processes of the bowel are characterized by an accumulation of eosinophils at inflammation sites. The mechanisms that govern mucosal infiltration with eosinophils are not fully understood. In this work, we studied the colorectal polyp-confined tissue containing eosinophils and we hypothesized that intestinal epithelial cells are the cell source of eotaxin-3 or CCL26, a potent chemoattractant for eosinophils. We analyzed colorectal polyps (n=50) from pediatric patients with rectal bleeding by H&E staining and eosin staining, and different pro-inflammatory cytokines were assessed by RT-qPCR and ELISA. IgE and CCL26 were investigated by RT-qPCR, ELISA and confocal microscopy. Finally, the intracellular signaling pathway that mediates the CCL26 production was analyzed using a kinase array and immunoblotting in human intestinal Caco-2 cell line. We found a dense cell agglomeration within the polyps, with a significantly higher frequency of eosinophils than in control adjacent tissue. IL-4 and IL-13 were significantly up-regulated in polyps and CCL26 was elevated in the epithelial compartment. Experiments with Caco-2 cells showed that the type-2 cytokine IL-13 increased STAT3 and STAT6 phosphorylation and eotaxin-3 secretion. The addition of the blocking antibody Dupilumab or the inhibitor Ruxolitinib to the cytokine-stimulated Caco-2 cells diminished the CCL26 secretion to basal levels in a dose-dependent manner. In conclusion, our findings demonstrate a high frequency of eosinophils, and elevated levels of type-2 cytokines and eotaxin-3 in the inflammatory stroma of colorectal polyps from pediatric patients. Polyp epithelial cells showed to be the main cell source of CCL26, and IL-13 was the main trigger of this chemokine through the activation of the STAT3/STAT6/JAK1-2 pathway. We suggest that the epithelial compartment actively participates in the recruitment of eosinophils to the colonic polyp-confined inflammatory environment.

Evaluating Eosinophilic Colitis as a Unique Disease Using Colonic Molecular Profiles: A Multi-Site Study

BACKGROUND & AIMS

Colonic eosinophilia, an enigmatic finding often referred to as eosinophilic colitis (EoC), is a poorly understood condition. Whether EoC is a distinct disease or a colonic manifestation of eosinophilic gastrointestinal diseases (EGIDs) or inflammatory bowel disease (IBD) is undetermined.

METHODS

Subjects with EoC (n = 27) and controls (normal [NL, n = 20], Crohn's disease [CD, n = 14]) were enrolled across sites associated with the Consortium of Eosinophilic Gastrointestinal Disease Researchers. EoC was diagnosed as colonic eosinophilia (ascending ≥100, descending ≥85, sigmoid ≥65 eosinophils/high-power field) with related symptoms. Colon biopsies were subjected to RNA sequencing. Associations between gene expression and histologic features were analyzed with Spearman correlation; operational pathways and cellular constituents were computationally derived.

RESULTS

We identified 987 differentially expressed genes (EoC transcriptome) between EoC and NL (>1.5-fold change, P < .05). Colonic eosinophil count correlated with 31% of EoC transcriptome, most notably with CCL11 and CLC (r = 0.78 and 0.77, P < .0001). Among EoC and other EGIDs, there was minimal transcriptomic overlap and minimal evidence of a strong allergic type 2 immune response in EoC compared with other EGIDs. Decreased cell cycle and increased apoptosis in EoC compared with NL were identified by functional enrichment analysis and immunostaining using Ki-67 and cleaved caspase-3. Pericryptal circumferential eosinophil collars were associated with the EoC transcriptome (P < .001). EoC transcriptome-based scores were reversible with disease remission and differentiated EoC from IBD, even after controlling for colonic eosinophil levels (P < .0001).

CONCLUSIONS

We established EoC transcriptomic profiles, identified mechanistic pathways, and integrated findings with parallel IBD and EGID data. These findings establish EoC as a distinct disease compared with other EGIDs and IBD, thereby providing a basis for improving diagnosis and treatment.

Immune Activation in Functional Dyspepsia: Bystander Becoming the Suspect

Disorders of gut-brain interaction (DGBI), formerly termed functional gastrointestinal disorders (FGID), are highly prevalent although exact pathophysiological mechanisms remain unclear. Intestinal immune activation has been recognized, but increasing evidence supports a pivotal role for an active inflammatory state in these disorders. In functional dyspepsia (FD), marked eosinophil and mast cell infiltration has been repeatedly demonstrated and associations with symptoms emphasize the relevance of an eosinophil-mast cell axis in FD pathophysiology. In this Review, we highlight the importance of immune activation in DGBI with a focus on FD. We summarize eosinophil biology in both homeostasis and inflammatory processes. The evidence for immune activation in FD is outlined with attention to alterations on both cellular and molecular level, and how these may contribute to FD symptomatology. As DGBI are complex and multifactorial conditions, we shed light on factors associated to, and potentially influencing immune activation, including bidirectional gut-brain interaction, allergy and the microbiota. Crucial studies reveal a therapeutic benefit of treatments targeting immune activation, suggesting that specific anti-inflammatory therapies could offer renewed hope for at least a subset of DGBI patients. Lastly, we explore the future directions for DGBI research that could advance the field. Taken together, emerging evidence supports the recognition of FD as an immune-mediated organic-based disorder, challenging the paradigm of a strictly functional nature.

The aryl hydrocarbon receptor contributes to tissue adaptation of intestinal eosinophils in mice

Eosinophils are potent sources of inflammatory and toxic mediators, yet they reside in large numbers in the healthy intestine without causing tissue damage. We show here that intestinal eosinophils were specifically adapted to their environment and underwent substantial transcriptomic changes. Intestinal eosinophils upregulated genes relating to the immune response, cell-cell communication, extracellular matrix remodeling, and the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor with broad functions in intestinal homeostasis. Eosinophils from AHR-deficient mice failed to fully express the intestinal gene expression program, including extracellular matrix organization and cell junction pathways. AHR-deficient eosinophils were functionally impaired in the adhesion to and degradation of extracellular matrix, were more prone to degranulation, and had an extended life span. Lack of AHR in eosinophils had wider effects on the intestinal immune system, affecting the T cell compartment in nave and helminth-infected mice. Our study demonstrates that the response to environmental triggers via AHR partially shapes tissue adaptation of eosinophils in the small intestine.

Risk Factors of Clinical Relapses in Pediatric Luminal Crohn's Disease: A Retrospective Cohort Study

INTRODUCTION

There is currently little knowledge on factors associated with the relapse of Crohn's disease (CD) in children. The aims of this study were to describe the risk factors associated with relapse in pediatric CD and the changes in the relapse rate over the past decade.

METHODS

Patients younger than 18 years and diagnosed between 2009 and 2019 were included in this retrospective cohort study. Clinical, endoscopic, histological, and laboratory data, as well as induction and maintenance treatments, were collected from the medical records. Survival analyses and Cox regression models were used to assess the impact of these risk factors on relapse.

RESULTS

Six hundred thirty-nine patients were included. There was a decrease in the clinical relapse rate over the past decade: 70.9% of the patients diagnosed between 2009 and 2014 relapsed as compared with 49.1% of the patients diagnosed between 2015 and 2019 (P < 0.0001). The following variables were associated with clinical relapse: female sex (adjusted hazard ratio [aHR] = 1.52, P = 0.0007), exposure to oral 5-ASA (aHR = 1.44, P = 0.04), use of immunomodulatory agents compared with tumor necrosis factor-alpha inhibitors (methotrexate aHR = 1.73, P = 0.003; thiopurines aHR = 1.63, P = 0.002), presence of granulomas (aHR = 1.34, P = 0.02) and increased eosinophils on intestinal biopsies (aHR = 1.36, P = 0.02), high levels of C-reactive protein (aHR = 1.01, P < 0.0001) and fecal calprotectin (aHR = 1.08, P < 0.0001), and low serum infliximab levels (aHR = 2.32, P = 0.001).

DISCUSSION

Relapse of pediatric CD has decreased in the past decade. The risk of relapse is significantly associated with clinical, endoscopic, histological, and laboratory variables and treatment strategies.

Impressions and aspirations from the FDA GREAT VI Workshop on Eosinophilic Gastrointestinal Disorders Beyond Eosinophilic Esophagitis and Perspectives for Progress in the Field

The US Food and Drug Administration hosted a workshop on July 21, 2021, to discuss the disease characteristics, natural history, and end points to assess treatment benefit in patients with eosinophilic gastrointestinal disorders (EGIDs) beyond eosinophilic esophagitis (EoE). Notably, EGIDs beyond EoE, such as eosinophilic gastritis, eosinophilic enteritis, and eosinophilic colitis, herein referred to as non-EoE EGIDs, are understudied relative to EoE. This workshop provided a forum for open discussion among stakeholders-medical professionals (including their societies and research groups), Food and Drug Administration representatives, an industry representative, and a patient representative-to facilitate drug development. Experts in many disciplines related to EGIDs, including allergy, immunology, epidemiology, gastroenterology, and pathology, and both adult and pediatric clinicians contributed. Herein, we discuss some of the insights of the material presented at the meeting and present perspectives on moving the field forward toward drug approval.

A Quantitative Assessment of Mucosal Eosinophils in the Gastrointestinal Tract of Children Without Detectable Organic Disease

BACKGROUND

Accurate measurements of mucosal eosinophil concentrations in gastrointestinal tracts of healthy children are necessary to differentiate health and disease states in general, and better define eosinophilic gastrointestinal diseases.

STUDY

We retrospectively reviewed gastrointestinal biopsies from children with macroscopically normal endoscopies, who, after a minimal follow-up of one year, were not diagnosed with any organic disease. Peak eosinophil concentrations and distributions were assessed from each segment of the gastrointestinal tract.

RESULTS

Three centers (Italy, United Kingdom, and Israel) contributed 202 patients (median age 13 years IQR 9.5-15.5, range 1-18 years). Median (IQR, range) eosinophil concentrations (eos/mm²) were: esophagus 0 (0-0, 0-84), stomach 0 (0-4, 0-84), duodenal bulb 20 (13-30, 7-67), second part of duodenum 20 (13-29, 0-105), terminal ileum 29 (14-51, 0-247), cecum 53 (37-89, 10-232), ascending colon 55 (25-84, 0-236), transverse colon 38 (21-67, 4-181), descending colon 29 (17-59, 0-114), sigmoid colon 25 (13-40, 0-215) and rectum 13 (4-28, 0-152). Significant geographical variance was present, however, no differences in eosinophil concentrations were identified between children with resolving symptoms vs. those with functional diagnoses, nor across age groups.

CONCLUSIONS

Standardized eosinophil concentrations from the gastrointestinal tracts of children without organic disease will serve to better define both health and disease states. No differences were found between resolved symptoms vs. functional diagnoses nor between age groups in this pediatric cohort.

Changes in the clinical phenotype and behavior of pediatric luminal Crohn's disease at diagnosis in the last decade

BACKGROUND AND AIMS

The aims of this study were to describe the trends in the behavior of pediatric CD during the last decade and to describe the seasonal variation of disease presentation.

METHODS

Patients under 18 years old and diagnosed between 2009 and 2019 were included. The clinical, endoscopic, histological, and laboratory data were collected from the medical records. We analyzed the trends of these parameters according to the year and season of diagnosis.

RESULTS

654 patients were included in the study. The number of incident CD cases increased yearly. Patients diagnosed between 2015 and 2019 were younger at diagnosis (OR 2.53, p = 0.02), had more perianal diseases (OR: 2.30, p < 0.0001) and more granulomas (OR: 1.61, p = 0.003), but fewer eosinophils (OR: 0.35, p < 0.0001) and less chronic lymphoplasmacytic infiltrate (OR: 0.56, p = 0.008) as compared to the 2009-2014 cohort. There was fewer CD diagnosis during winter. Patients diagnosed in the fall had lower PCDAIs, less failure to thrive and less extensive digestive involvement. Colonic disease was significantly more frequent during summer and fall.

CONCLUSION

The clinical and histological phenotype of CD has changed over time and there are important seasonal trends in the frequency and severity on disease behavior suggesting possible disease triggers.

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.

A Pattern-based Pathology Approach to Very Early-onset Inflammatory Bowel Disease: Thinking Beyond Crohn Disease and Ulcerative Colitis

Very early-onset inflammatory bowel disease (VEO-IBD), IBD diagnosed in children younger than 6 years old, is phenotypically and genetically distinct from older onset IBD. Monogenic and digenic causative defects, particularly in primary immunodeficiency and intestinal epithelial barrier genes, have been identified in a subset of patients with VEO-IBD allowing for targeted therapies and improved outcomes. However, these findings are the minority, thus strategies to correctly diagnose patients, including identification of specific histopathologic findings with correlating clinical and laboratory features may provide critical and necessary insight into mechanisms of disease pathogenesis and subsequent therapeutic options. In this article, we review the pathologic findings seen in patients with VEO-IBD and outline a pattern-based approach to diagnosis using examples from primary immunodeficiencies with gastrointestinal manifestations.

Clinical features of pediatric eosinophilic gastroenteritis

BACKGROUND

No study has analyzed more than100 cases of eosinophilic gastroenteritis (EGE) in children in a single center. We aimed to describe the clinical features of pediatric EGE.

METHODS

This retrospective study was conducted at a single center. Between April 2007 and December 2017, 860 children between the ages of 1 year and 15 years underwent endoscopy for gastrointestinal symptoms of unknown cause. Among them, 109 (12.7%) were diagnosed with EGE according to the diagnostic criteria for EGE developed by the research group of the Ministry of Health, Labour and Welfare of Japan for eosinophilic gastrointestinal disorder in 2015. We investigated their symptoms, comorbidities, endoscopic findings, pathological findings, treatments, and outcomes.

RESULTS

Seventy-one boys (65.1%) and 38 girls (34.9%) were diagnosed with EGE. The median age at diagnosis was 11 years (range, 1-15 years). The chief complaints were abdominal pain in 83 (76.1%) and diarrhea in 26 (23.9%). Upper and lower gastrointestinal endoscopies showed normal findings in 32 patients (29.4%). The most common treatment was a combination of elimination of foods suspected of causing EGE and anti-allergic agents in 50 cases (45.9%). The outcomes were symptom disappearance in 43 patients (39.4%) and symptom improvement in 53 patients (48.6%).

CONCLUSIONS

For gastrointestinal symptoms of unknown cause in children, EGE should be considered as a differential diagnosis. Although the symptoms and endoscopic findings are nonspecific, cracked mucosa may be a specific endoscopic finding for pediatric EGE. An elimination diet and/or anti-allergic drugs were effective in most patients with pediatric EGE.

Factors associated with time to clinical remission in pediatric luminal Crohn's disease: A retrospective cohort study

Background and Aim

Data on factors influencing time to remission in pediatric Crohn's disease (CD) are very limited in the literature. The aim of this retrospective cohort study was to describe the trends of time to clinical remission over the past decade and to identify factors associated with time to clinical remission in children with luminal CD.

Methods

Patients under 18 years old diagnosed between 2009 and 2019 were included. All data were collected from the patients' medical records. Survival analyses and linear regression models were used to assess the impact of clinical, laboratory, endoscopic, histological, and therapeutic factors on time to clinical remission.

Results

A total of 654 patients were included in the study. There was no change in the time to clinical remission over the decade. Female sex in adolescents (adjusted bêta regression coefficient [aβ] = 31.8 days, P = 0.02), upper digestive tract involvement (aβ = 46.4 days, P = 0.04) perianal disease (aβ = 32.2 days, P = 0.04), presence of active inflammation on biopsies at diagnosis (aβ = 46.7 days, P = 0.01) and oral 5‐aminosalicylates (5‐ASA) exposure (aβ = 56.6 days, P = 0.002) were associated with longer time to clinical remission. Antibiotic exposure (aβ = −29.3 days, P = 0.04), increased eosinophils (aβ = −29.6 days, P = 0.008) and combination of exclusive enteral nutrition with tumor‐necrosis‐factor‐alpha (TNF‐alpha) inhibitors as induction therapy (aβ = −36.8 days, P = 0.04) were associated with shorter time to clinical remission.

Conclusion

In children with newly diagnosed Crohn's disease, time to clinical remission did not shorten during the decade. It was associated with baseline clinical and histological data and treatment strategies. Combination of enteral nutrition and TNF‐alpha inhibitors was associated with faster clinical remission.

Esophageal Eosinophilia and Eosinophilic Esophagitis in Celiac Children: A Ten Year Prospective Observational Study

The association between eosinophilic esophagitis and celiac disease is still controversial and its prevalence is highly variable. We aimed to investigate the prevalence of esophageal eosinophilia and eosinophilic esophagitis in a large group of children with celiac disease, prospectively followed over 11 years.

METHODS

Prospective observational study performed between 2008 and 2019. Celiac disease diagnosis was based on ESPGHAN criteria. At least four esophageal biopsies were sampled in patients who underwent endoscopy. The presence of at least 15 eosinophils/HPF on esophageal biopsies was considered suggestive of esophageal eosinophilia; at the same time, eosinophilic esophagitis was diagnosed according to the International Consensus Diagnostic Criteria for Eosinophilic Esophagitis.

RESULTS

A total of 465 children (M 42% mean age 7.1 years (range: 1-16)) were diagnosed with celiac disease. Three hundred and seventy patients underwent endoscopy, and esophageal biopsies were available in 313. The prevalence of esophageal eosinophilia in children with celiac disease was 1.6% (95% CI: 0.54-2.9%). Only one child was diagnosed as eosinophilic esophagitis; we calculated a prevalence of 0.3% (95% CI: 0.2-0.5%). The odds ratio for an association between eosinophilic esophagitis and celiac disease was at least 6.5 times higher (95% CI: 0.89-47.7%; p = 0.06) than in the general population.

CONCLUSION

The finding of an increased number of eosinophils (>15/HPF) in celiac patients does not have a clinical implication or warrant intervention, and therefore we do not recommend routine esophageal biopsies unless clinically indicated.

Mast Cell and Eosinophil Counts in Gastric and Duodenal Biopsy Specimens From Patients With and Without Eosinophilic Gastroenteritis

BACKGROUND & AIMS

Mast cells are believed to contribute to the development of eosinophilic gastrointestinal disorders (EGIDs). We quantified mast cells and eosinophils in biopsy specimens from patients with EGIDs and without known esophageal or gastrointestinal disease to investigate associations between these cell types and EGID and its features.

METHODS

We conducted a retrospective study of patients with EGID (n = 52) and of children and adults who underwent upper endoscopy and were found to have no evidence of gastrointestinal or systemic conditions (n = 123). We re-reviewed archived gastric and duodenal biopsy specimens to quantify mast cells (by tryptase immunohistochemistry) and eosinophils. We calculated the specificity of cell count thresholds for identification of patients with EGIDs and evaluated the correlation between mast cell and eosinophil counts and clinical and endoscopic features.

RESULTS

In the gastric biopsy specimens from patients without esophageal or gastrointestinal diseases, the mean mast cell count was 18.1 ± 7.2 cells per high-power field (hpf), and the peak mast cell count was 21.9 ± 8.2 cells/hpf. In the duodenal biopsy specimens from patients without esophageal or gastrointestinal diseases, the mean mast cell count was 23.6 ± 8.1 cells/hpf and the peak mast cell count was 28.1 ± 9.3 cells/hpf. The mean and peak eosinophil counts in gastric biopsy specimens from patients without disease were 3.8 ± 3.6 eosinophils/hpf and 5.8 ± 5.0 eosinophils/hpf; the mean and peak eosinophil counts in duodenal biopsy specimens were 14.6 ± 8.9 eosinophils/hpf and 19.5 ± 11.0 eosinophils/hpf. A mean count of 20 eosinophils/hpf in gastric biopsy specimens or 30 eosinophils/hpf in duodenal biopsy specimens identified patients with EGIDs with high specificity. Gastric and duodenal biopsy specimens from patients with EGIDs had significant increases in mean mast cell counts compared with biopsy specimens from patients without EGIDs. There was a correlation between mean mast cell and eosinophil counts in duodenal biopsy specimens (R = 0.47; P = .01). The mean mast cell and eosinophil counts did not correlate with symptoms or endoscopic features of EGIDs.

CONCLUSIONS

We identified thresholds for each cell type that identified patients with EGIDs with 100% specificity. The increased numbers of mast cells and eosinophils in gastric and duodenal tissues from patients with EGIDs supports the concept that these cell types are involved in pathogenesis. However, cell counts are not associated with symptoms or endoscopic features of EGIDs.

Clinical Characteristics and Outcomes of Eosinophilic Colitis in Patients With Cancer

BACKGROUND

Eosinophilic colitis (EoC) is a rare form of eosinophilic gastrointestinal disease characterized by diffuse eosinophilic infiltration in the deep lamina propria of colonic mucosa. The pathophysiology is unclear, but EoC has been associated with multiple known risk factors.

AIM

The aim of this study was to characterize the clinical characteristics and disease course of patients with EoC at a major cancer center.

MATERIAL AND METHODS

We retrospectively reviewed colonic samples obtained between January 2000 and December 2018 from our institutional database and included cases with significant colonic eosinophilia. Baseline clinical data and EoC-related clinical course and outcomes were documented.

RESULTS

Forty-one patients were included. One fourth had coexisting autoimmune conditions. Seventy-eight percent had a cancer diagnosis. Half the patients received chemotherapy, with a median duration of 180 days between chemotherapy and EoC onset. Symptoms were present in 76% of patients. Diarrhea was more prevalent in patients who received chemotherapy (85% vs. 42%). Median duration of EoC symptoms was 30 days in patients with cancer and 240 days in those without cancer (P=0.03). Most patients (88%) had normal colonoscopy findings. Fifteen percent of patients required hospitalization. All-cause mortality was 37%, mostly related to underlying malignancy and organ failure.

CONCLUSIONS

EoC in cancer patients appears to have more diarrhea-predominant symptoms, particularly in patients receiving chemotherapy, but a shorter disease duration compared with patients without cancer. Hospitalization can be required for serious cases. Treatment may be reserved for patients requiring symptom management, as most patients with EoC have good clinical outcomes regardless of treatment.

Developing a standardized approach for assessing mast cells and eosinophils on tissue biopsies: A Work Group Report of the AAAAI Allergic Skin Diseases Committee

Mast cells and eosinophils are commonly found, expectedly or unexpectedly, in human tissue biopsies. Although the clinical significance of their presence, absence, quantity, and quality continues to be investigated in homeostasis and disease, there are currently gaps in knowledge related to what constitutes quantitatively relevant increases in mast cell and eosinophil number in tissue specimens for several clinical conditions. Diagnostically relevant thresholds of mast cell and eosinophil numbers have been proposed and generally accepted by the medical community for a few conditions, such as systemic mastocytosis and eosinophilic esophagitis. However, for other mast cell- and eosinophil-associated disorders, broad discrepancies remain regarding diagnostic thresholds and how samples are processed, routinely and/or specially stained, and interpreted and/or reported by pathologists. These discrepancies can obfuscate or delay a patient's correct diagnosis. Therefore, a work group was assembled to review the literature and develop a standardized consensus for assessing the presence of mast cells and eosinophils for a spectrum of clinical conditions, including systemic mastocytosis and cutaneous mastocytosis, mast cell activation syndrome, eosinophilic esophagitis, eosinophilic gastritis/enteritis, and hypereosinophilia/hypereosinophilic syndrome. The intent of this work group is to build a consensus among pathology, allergy, dermatology, hematology/oncology, and gastroenterology stakeholders for qualitatively and quantitatively assessing mast cells and eosinophils in skin, gastrointestinal, and bone marrow pathologic specimens for the benefit of clinical practice and patients.

Organ-Specific Hypereosinophilic Syndrome Presenting as Eosinophilic Gastroenteritis

Gastrointestinal (GI) diseases have a substantial impact on the population health and healthcare resources of the United States. They constitute billions of dollars in expenditure and millions of office and hospital visits. With advancing diagnostic and treatment modalities, rare diseases are increasingly recognized and managed. However, after close to 80 years since the first description, eosinophilic GI disorders (EGID) are still uncommon, and only around 300 cases have been reported to date. Hypereosinophilic syndrome (HES) is well studied, but there are still no guidelines to direct management. We report the case of a 56-year-old female who presented with gastroenteritis and a persistent eosinophil count above 7 x 10⁹/L. Imaging was suggestive of bowel wall thickening, and endoscopy revealed normal-appearing mucosa. However, histologic examination revealed eosinophilic infiltration of the GI tract. She was diagnosed with HES and treated with oral prednisone with remarkable improvement of her symptoms.

Gastrointestinal Eosinophil Responses in a Longitudinal, Randomized Trial of Peanut Oral Immunotherapy

BACKGROUND & AIMS

Gastrointestinal side effects are common during oral immunotherapy (OIT) and eosinophilic esophagitis (EoE) is a potential complication. We aimed to characterize eosinophilic gastrointestinal responses to peanut OIT, in which peanut protein is given orally, with incremental increases in dose over time.

METHODS

Twenty adults with IgE-mediated peanut allergy were randomly assigned to groups given peanut OIT (n = 15) or placebo (n = 5); 1 additional subject withdrew before randomization. Serial gastrointestinal biopsies were collected at baseline (n = 21, 0 weeks), following dose escalation (n = 10, 52 weeks), and during the maintenance phase (n = 11, 104 weeks). Endoscopic findings were characterized using the EoE endoscopic reference score. Biopsies were assessed for eosinophils per high-power field (eos/hpf) and other pathology features using EoE histologic scoring system scores. We performed immunohistochemical analyses of eosinophil peroxidase deposition, quantified using automated image analysis.

RESULTS

At baseline, no subjects reported current gastrointestinal symptoms. However, 3 of the 21 subjects (14%) had esophageal peak eosinophil counts ≥15 eos/hpf and all subjects had dilated intercellular spaces (DIS). OIT induced or exacerbated esophageal eosinophilia (EE) at 52 weeks in most subjects (peak eosinophil counts >5 eos/hpf in 6 of 7 patients [86%]; peak eosinophil counts ≥15 eos/hpf in 4 of 7 patients [57%]). One subject met clinicopathologic criteria for EoE and withdrew; no significant changes in esophageal peak eosinophil counts were observed in the placebo group. EE in the OIT group corresponded with significant increases in EoE histologic scoring system scores and deposition of eosinophil peroxidase. In 4 of 6 participants (67%), OIT-induced EE and gastrointestinal eosinophilia resolved by the end of the maintenance phase. Gastrointestinal symptoms were not clearly associated with EE or gastrointestinal eosinophilia.

CONCLUSIONS

In this pilot study, we found that peanut OIT-induced EE and gastrointestinal eosinophilia are usually transient and are not always associated with gastrointestinal symptoms. Clinicaltrials.gov no: NCT02103270.

Utility of gastric and duodenal biopsy sampling in adult eosinophilic esophagitis patients to rule out other gastrointestinal disorders

RATIONALE

According to consensus guidelines, if eosinophilic esophagitis (EoE) is suspected, not only esophageal but also gastric and duodenal biopsy specimens should be sampled in order to exclude other generalized or eosinophilic gastrointestinal (GI) disorders, such as eosinophilic gastroenteritis or celiac disease. However, the diagnostic yield for this remains unclear.

AIM

To assess the diagnostic yield of biopsy sampling from the stomach and duodenum in adult EoE patients to rule out generalized or eosinophilic GI disorders.

METHODS

A retrospective chart-review was conducted in untreated adult EoE patients that underwent upper endoscopy with biopsies sampled from the esophagus, stomach and duodenum. Standardized (electronic) case-report forms were used to extract clinical, endoscopic and histologic data.

RESULTS

In total, 93 adults (71% males, age 36.4 (interquartile range 28.4 - 49.1) years) with untreated EoE (≥15 eosinophils/high-power-field) were included. Symptoms of dysphagia and food impaction were reported in 93% and 58%, respectively of the patients. Typical endoscopic EoE-features were present in 77 (85%) patients. The yield of routinely sampled gastric and duodenal biopsy specimens in our cohort was 3.6% (95% confidence interval: 2.6-4.8%) (n/N = 1/93) for a relevant other generalized or eosinophilic GI diagnosis and 30% for other histological diagnosis such as non-specific or H. Pylori gastritis. In total, 62 (67%) patients presented with other GI symptoms and/or endoscopic abnormalities of the stomach and/or duodenum - which both may be suggestive for other relevant GI conditions. The diagnostic yield for a relevant generalized or eosinophilic GI disorder in this subgroup was, 4.8% (95%CI 3.4 - 6.7%) (n/N = 1/62).

CONCLUSION

Gastric and duodenal biopsy specimens seem to have limited diagnostic value for the exclusion of generalized or eosinophilic GI disorders in adults with EoE.KEY POINTSEvidence is lacking on the diagnostic value of additional biopsies sampled form the stomach and duodenum to rule out other relevant generalized or eosinophilic gastrointestinal (GI) disorders.The yield of gastric and duodenal biopsies routinely sampled in our cohort was 3.6% for a relevant other generalized or eosinophilic GI diagnosis and 30% for other histological diagnosis such as non-specific or H. Pylori gastritis.The diagnostic yield for a relevant generalized or eosinophilic GI disorder in the subgroup of patients (67%) presenting with other GI symptoms and/or endoscopic abnormalities of the stomach and/or duodenum - which both may be suggestive for other relevant GI conditions was, 4.8%.Gastric and duodenal biopsy specimens seem to have limited diagnostic value for the exclusion of generalized or eosinophilic GI disorders in adults with EoE.

Colonic mucosal eosinophilia in children without inflammatory bowel disease

Children undergoing colonoscopy and mucosal biopsies may show increased colonic mucosal eosinophils, which may or may not be associated with inflammatory bowel disease. There is not much clinical data on American children who have isolated increased colonic mucosal eosinophils. We sought to study the clinical correlates of children without inflammatory bowel disease who show increased mucosal eosinophils to understand their clinical presentation, etiological associations, and outcome. A retrospective analysis of children seen at a tertiary-level Children's hospital was performed by reviewing their medical charts and extracting pertinent data. There were 110 children in the study who had increased colonic mucosal eosinophils. Most children presented with abdominal pain, but several of them also had constipation, blood in stools, and diarrhea. Food allergies, irritable bowel syndrome, asthma, and lactase deficiency were the top four conditions present in these patients. Pathology of the colonic distribution revealed involvement of more than two colonic regions in 86% of the subjects, and only two subjects showing epithelial or crypt involvement by eosinophils. All subjects had a good outcome. Children with colonic mucosal eosinophilia (CME) who do not have an inflammatory bowel disease most frequently present with abdominal pain and primarily an increase of lamina propria eosinophils in two or more colonic regions. Based on the etiological associations we noted in the study, a work-up of children with CME may encompass detailed history for functional gastrointestinal disorders and lactose intolerance, testing for food and environmental allergies, stool examination for parasites, and peripheral blood counts. Almost all children had resolution of symptoms in the studied period suggesting that CME in children has a good clinical outcome.

Beyond Helicobacter: dealing with other variants of gastritis-an algorithmic approach

In daily practice, the presence of inflammation in gastric biopsies prompts a mental algorithm, an early question being whether the lesion present is Helicobacter-associated. If Helicobacter organisms are not found, then there is a further algorithm, governed by the predominant type of inflammatory cells present, and the presence of other features such as intraepithelial lymphocytosis, a subepithelial collagen band, granulomas, coexisting chronic inflammation, focality, and superimposed reactive changes including erosions and ulcers. Each of these generates its own differential diagnosis. If no inflammation is present, then the two major changes specifically looked for are the changes associated with hypergastrinaemia, by far the most common cause of which is treatment with proton pump inhibitors, and reactive changes. These may be present with and without accompanying inflammation, and, when the epithelial changes dominate, the term gastropathy is preferred. In this article, we present an approach to non-Helicobacter inflammation and gastropathies.

Eosinophilic colitis in adults

Eosinophilic colitis (EoC) is a pathological entity associated with abnormal infiltration of colonic mucosa by eosinophilic polynuclear cells (Eo). This is a relatively common pathology in infants and children under 2 years old, but is more rare and has been less studied in adults. EoC can be classified as primary or secondary. Primary EoC is, in the majority of cases, related to an allergic reaction, either IgE-mediated and capable of causing an anaphylactic-type food allergy, or not mediated by IgE and capable of giving rise to food enteropathy. The symptoms for adults with EoC are variable and non-specific, diarrhoea and abdominal pain being the most common signs. There is no histological consensus for the diagnosis of EoC. The presence of over 40 Eo per high-power field (×400) in at least two different colonic segments could be suggested as the criterion for the diagnosis. In adults with primary EoC, skin tests are of limited value and the response to a restrictive diet is less effective than in young children, given that IgE or non-IgE-mediated allergic reactions are rarely identified and EoC generally require medical treatment. There is no consensus on the treatment of EoC, but the potential efficacy of corticosteroids and budesonide has been demonstrated in the vast majority of cases studied.

Genetic and shared environmental risk factors do not lead to eosinophil activation in healthy twins of IBD patients

OBJECTIVE

To examine the role of eosinophils in the pre-diagnostic phase of inflammatory bowel disease (IBD), we studied the influence of genetic and shared environmental risk factors in a twin cohort of IBD.

MATERIAL AND METHODS

We analysed eosinophil derived neurotoxin (EDN) and eosinophil cationic protein (ECP) in faecal samples from twin pairs with Crohn's disease (n = 37) or ulcerative colitis (n = 21) and from external healthy controls (n = 44). Eosinophils stained with eosinophil peroxidase (EPO) were quantified in rectal biopsies. Ratios with 95% confidence intervals were calculated.

RESULTS

Twins with Crohn' disease displayed higher levels of EDN (Ratio = 2.98, 1.65-5.37) and ECP (Ratio 1.83, 1.24-2.70) than their healthy siblings. Levels did not differ between healthy twin-siblings and external controls (EDN, Ratio = 1.52, 0.79-2.94 and ECP, Ratio = 0.93, 0.56-1.54). Higher levels of EDN (Ratio = 2.43, 1.13-5.24) and ECP (Ratio = 1.53, 0.92-2.53) were observed among twins with ulcerative colitis vs their healthy siblings. Levels did not differ between healthy twin-siblings and external controls (EDN, Ratio = 1.08, 0.51-2.25 and ECP, Ratio = 1.29, 0.74-2.26). Using intra-class correlation coefficient (ICC), we found no agreement in levels of EDN or ECP in discordant pairs, except for ECP in monozygotic Crohn's disease pairs (ICC = 0.63). In contrast, agreement was observed in monozygotic pairs concordant for Crohn's disease (EDN, ICC = 0.67 and ECP, ICC = 0.66). The number of eosinophils in rectum was increased in twins with ulcerative colitis vs their healthy sibling (Ratio = 2.22, 1.50-3.27).

CONCLUSIONS

Activation of eosinophils in IBD seems to be a consequence of inflammation rather than an effect of genetic and shared environmental risk factors alone.

Food protein-induced allergic proctocolitis in infants: Literature review and proposal of a management protocol

Food protein-induced allergic proctocolitis (FPIAP) is a condition characterized by inflammatory changes in the distal colon in response to one or more foreign food proteins because of immune-mediated reactions.

FPIAP prevalence estimates range widely from 0.16% in healthy children and 64% in patients with blood in stools.

In clinical practice, FPIAP is diagnosed when patients respond positively to the elimination of a suspected triggering food allergen. Nevertheless, significant proportions of infants get misdiagnosed with IgE mediated allergy and undergo unnecessary dietary changes.

Diagnosis is based on clinical symptoms, a good response to an allergen-free diet and the recurrence of symptoms during the “allergy challenge test”. Sometimes clinical features may be non-specific and the etiology of rectal bleeding in childhood may be heterogeneous. Therefore, it is crucial to exclude a variety of other possible causes of rectal bleeding in the pediatric age group, including infection, anal fissure, intestinal intussusception and, in infants, necrotizing enterocolitis and very early onset inflammatory bowel disease. The diagnostic workup includes in those cases invasive procedures such as sigmoidoscopy and colonoscopy with biopsies.

The high prevalence of FPIAP contrasts with the lack of known information about the pathogenesis of this condition. For this reason and due to the absence of a review of the evidence, a literature review appears necessary to clarify some aspects of allergic colitis.

The aim of the review is to fill this gap and to lay the foundations for a subsequent evidence-based approach to the condition.

Eosinophilic colitis: an infrequent disease with difficult diagnose

Eosinophilic colitis (EC) is a rare entity. It is part of eosinophilic gastroenteritis, a rare inflammatory disorder characterised by eosinophilic infiltration of tissues that can affect any segment of the digestive tract. The diagnosis is established by the presence of an increased eosinophilic infiltrate in the colon wall in symptomatic patients. There is no characteristic clinical picture of EC. It can be associated with abdominal pain, changes in bowel movements, diarrhoea and rectal bleeding. Biopsies are mandatory if EC is suspected and despite visualising a normal mucosa. Although there are no protocol guidelines in this regard, steroid treatment is the first option in controlling the disease. Increasing the knowledge of clinicians and pathologists of this disorder and the recording its real incidence and population impact, could improve the understanding and treatment of the disease.

Single-Organ and Multisystem Hypereosinophilic Syndrome Patients with Gastrointestinal Manifestations Share Common Characteristics

BACKGROUND

Eosinophilic gastrointestinal diseases (EGIDs) are defined by marked eosinophilia in the gastrointestinal (GI) tract resulting in a wide variety of GI symptoms. When accompanied by blood hypereosinophilia (HE; absolute eosinophil count ≥1500/mm3), EGID can occur as an isolated GI disorder (hypereosinophilic syndrome [HES]/EGID overlap) or as part of a multisystem hypereosinophilic syndrome (Multisystem HES).

OBJECTIVE

To describe the GI disease of patients categorized as those with HES/EGID overlap versus those with Multisystem HES.

METHODS

Consecutively enrolled patients on a natural history protocol to study eosinophilia with biopsy-proven EGID involving the esophagus, stomach, small-bowel, and/or colon were evaluated for clinical, histopathologic, and endoscopic features by retrospective chart review.

RESULTS

Among the 56 patients with EGID and HE, 34 were categorized as HES/EGID overlap and 22 as Multisystem HES. Demographics, GI symptoms, and associated comorbidities were similar between the 2 groups. Multisegment GI eosinophilia was present in 20 of 30 (67%) patients who underwent tissue sampling of all 4 GI segments. Tissue eosinophilia in all 4 GI segments was found in 5 of 30 (17%) patients. Dietary therapy was more common in patients with HES/EGID overlap (65% vs 23%, P = .0028). Patients with Multisystem HES were more likely to receive glucocorticoids (100% vs 79%, P = .0349) and nonglucocorticoid systemic therapies (77% vs 38%, P = .0061). One-third (8 of 22) of patients with Multisystem HES presented with isolated GI symptoms before developing extraintestinal manifestations at a median of 1 year (range, 0.25-15 years).

CONCLUSION

There are striking clinical similarities between patients with Multisystem HES and those with HES/EGID overlap, despite differing treatment approaches. Moreover, Multisystem HES can present with isolated GI involvement. Larger prospective studies are needed to confirm these findings.

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.

Association Between Endoscopic and Histologic Findings in a Multicenter Retrospective Cohort of Patients with Non-esophageal Eosinophilic Gastrointestinal Disorders

BACKGROUND

Little is known about the endoscopic and histologic findings of non-esophageal eosinophilic gastrointestinal diseases (EGID).

AIM

To characterize the presenting endoscopic and histologic findings in patients with eosinophilic gastritis (EG), eosinophilic gastroenteritis (EGE), and eosinophilic colitis (EC) at diagnosis and 6 months after initiating the treatment.

METHODS

We conducted a retrospective cohort study at 6 US centers associated with the Consortium of Eosinophilic Gastrointestinal Researchers. Data abstracted included demographics, endoscopic findings, tissue eosinophil counts, and associated histologic findings at diagnosis and, when available, after initial treatment.

RESULTS

Of 373 subjects (317 children and 56 adults), 142 had EG, 123 EGE, and 108 EC. Normal endoscopic appearance was the most common finding across all EGIDs (62% of subjects). Baseline tissue eosinophil counts were quantified in 105 (74%) EG, 36 (29%) EGE, and 80 (74%) EC subjects. The mean peak gastric eosinophil count across all sites was 87 eos/hpf for EG and 78 eos/hpf for EGE. The mean peak colonic eosinophil count for EC subjects was 76 eos/hpf (range 10-500). Of the 29% of subjects with post-treatment follow-up, most had an improvement in clinical, endoscopic, and histologic findings regardless of treatment utilized. Reductions in tissue eosinophilia correlated with improvements in clinical symptoms as well as endoscopic and histologic findings.

CONCLUSIONS

In this large cohort, normal appearance was the most common endoscopic finding, emphasizing the importance of biopsy, regardless of endoscopic appearance. Decreased tissue eosinophilia was associated with improvement in symptoms, endoscopic, and histologic findings, showing that disease activity is reversible.

Distribution of eosinophils in the gastrointestinal tract of children with no organic disease

Background

This study aimed to assess the eosinophil (eos) density of the mucosa of the gastrointestinal (GI) tract in children undergoing endoscopic procedures following an extensive workup, without diagnosis of an organic disease.

Methods

Biopsies from GI endoscopies performed at 3 major children’s hospitals (Athens, Madrid and Rome), between January 2012 and June 2018, were evaluated by a single pathologist in each center. Peak eos counts were expressed /high power field and /mm². Other histological abnormalities were also reported.

Results

A total of 111 children (median age 11 years; 48 boys) underwent upper endoscopy (333 biopsies), while 44 (median age 12; 25 boys) underwent ileocolonoscopy (262 biopsies). The median (interquartile range) eos/mm² were as follows: esophagus 0 (0-0); stomach 10.2 (3.3-15.3); duodenum 56.1 (26.1-86.7); ileum 61.2 (49.0-91.8); cecum 76.5 (40.9-99.7); ascending colon 73.9 (49.5-131.4); transverse colon 66.3 (40.8-91.5); descending colon 66.3 (30.6-81.6); sigmoid colon 39.2 (27.8-51.0); and rectum 25.5 (9.8-45.8). Geographical variations in GI tissue eos counts were found amongst the participating centers, but the causative factors need further evaluation. Functional GI disorders according to the Rome IV criteria were diagnosed in 73 children (37 boys, median age 13 years). No differences were found between children with or without functional GI disorder diagnosis, with regard to eos density in the GI tract.

Conclusion

The reported peak counts of GI tissue eos in children with no organic diseases provide normative values that may be useful in the evaluation of children with GI symptoms suggestive of eosinophilic GI disorders.

Gastrointestinal involvement of primary skin diseases

Less is known about gastrointestinal (GI) involvement of primary skin diseases due to the difference in embryology, histology, microbiology and physiology between integument and alimentary tract. Oesophagus, following the oropharyngeal mucosa, is the most common GI segment affected by primary skin diseases, especially by eosinophilic oesophagitis, lichen planus and autoimmune bullous dermatoses like pemphigus vulgaris, mucosal membrane pemphigoid and epidermolysis bullosa acquisita. Eosinophilic oesophagitis is an emerging chronic atopic disease with oesophageal dysfunction as the typical presentation, and oesophageal narrowing, rings and stricture as late complications. Oesophageal lichen planus mainly involves the proximal to mid-oesophagus in elderly aged women with long-term oral mucosal lesions. In acute attack of pemphigus vulgaris, oesophageal involvement is not uncommon but often neglected and may cause sloughing oesophagitis (oesophagitis dissecans superficialis) with acute GI bleeding in rare cases. GI manifestation of hereditary bradykininergic angio-oedema with colicky acute abdomen mostly affects small intestine, usually in the absence of pruritus or urticaria, and is more severe and long-lasting than the acquired histaminergic form. Strong evidence supports association between inflammatory bowel disease, especially Crohn disease, and hidradenitis suppurativa/acne inversa. Patients with vitiligo need surveillance of autoimmune liver disease, autoimmune atrophic gastritis or coeliac disease when corresponding symptoms become suspect. Melanoma is the most common primary tumour metastatic to the GI tract, with small intestine predominantly targeted. Gastrointestinal involvement is not uncommon in disseminated mycosis fungoides. Extramammary Paget's disease is an intraepidermal adenocarcinoma of controversial origin, and a high association between the anogenital occurrence and colorectal adenocarcinoma has been reported. As GI tract is the largest organ system with multidimensional functions, dermatologists in daily practice should be aware of the gastrointestinal morbidities related to primary skin diseases for an early diagnosis and treatment.

Colonic mucosal inflammatory cells in children and adolescents with lactase deficiency

INTRODUCTION AND OBJECTIVES

Many of the symptoms of patients with lactose intolerance are due to fermentation of undigested lactose in the colonic lumen, which may also lead to inflammatory cell changes in the colonic mucosa. The objective of our project was to understand the histopathological changes involving infiltration of eosinophils and mast cells in the colonic mucosa of children with lactase deficiency (LD).

METHODS

In this retrospective study we studied colonic mucosa of children and adolescents with LD to determine if any pathological changes or inflammatory cell changes were present. Pathology reports and Hematoxylin and eosin stained slides were reviewed. Tryptase immunohistochemistry was performed for mast cell assessment.

RESULT

There were 30 subjects in the study who had a LD and 15 presented with diarrhea and 15 without diarrhea. The colonic mucosa of 35.5 % of the subjects revealed increased mucosal eosinophils. There was no increase of mast cells or lymphocytic colitis in any of the subjects. Excepting for the increased eosinophils in a subset of the subjects, all had a normal appearance of the colonic mucosa.

CONCLUSION

Colonic mucosa of children and adolescents with LD has a normal histological appearance in majority of the patients. However, 35 % of the patients could demonstrate elevated eosinophils. In primary LD without any comorbidity there is no increase of mast cells and lymphocytic cells in the colonic mucosa.

Gastrointestinal Manifestations of Hypereosinophilic Syndromes and Mast Cell Disorders: a Comprehensive Review

Hypereosinophilic syndrome and mastocytosis are relatively rare proliferative diseases encountered in the general population. However, allergists frequently consider these disorders in the differential of patients presenting with gastrointestinal, pulmonary, cutaneous, and allergic symptoms. Gastrointestinal symptoms are some of the most frequent and/or debilitating aspects of both disease states and in many cases lead to poor quality of life and functional limitation for the patient. They are the third most common clinical manifestation in hypereosinophilic syndrome and have been found to be the most distressful aspect of the disorder in those with systemic mastocytosis. Both eosinophils and mast cells play integral parts in normal gut physiology, but when and how exactly their effector functionality translates into clinically significant disease remains unclear, and the available literature regarding their pathophysiology remains sparse. Eosinophils and mast cells even, in fact, may not necessarily function in isolation from each other but can participate in bidirectional crosstalk. Both are affected by similar mediators and can also influence one another in a paracrine fashion. Their interactions include both production of soluble mediators for specific eosinophil and mast cell receptors (for example, eosinophil recruitment and activation by mast cells releasing histamine and eotaxin) as well as direct physical contact. The mechanistic relationship between clonal forms of hypereosinophilia and systemic mastocytosis has also been explored. The nature of gastrointestinal symptomatology in the setting of both hypereosinophilic syndrome and mast cell disease is frequently manifold, heterogeneous, and the lack of better targeted therapy makes diagnosis and management challenging, especially when faced with a substantial differential. Currently, the management of these gastrointestinal symptoms relies on the treatment of the overall disease process. In hypereosinophilia patients, systemic corticosteroids are mainstay, although steroid-sparing agents such as hydroxyurea, IFN-α, methotrexate, cyclosporine, imatinib, and mepolizumab have been utilized with varying success. In mastocytosis patients, anti-mediator therapy with antihistamines and mast cell stabilization with cromolyn sodium can be considered treatments of choice, followed by other therapies yet to be thoroughly studied, including the role of the low-histamine diet, corticosteroids, and treatment of associated IBS symptoms. Given that both eosinophils and mast cells may have joint pathophysiologic roles, they have the potential to be a combined target for therapeutic intervention in disease states exhibiting eosinophil or mast cell involvement.