Factors associated with long-term clinical outcome in microscopic colitis.

BACKGROUND AND AIMS: Microscopic colitis has been increasingly recognized as a cause of chronic diarrhoea. We aimed to characterize the role of disease-related factors and treatments on the clinical outcomes of microscopic colitis. METHODS: We retrospectively reviewed the medical records of patients with microscopic colitis who were treated at the University of Chicago and Oregon Health & Science University between August 2010 and May 2016. Patient characteristics and treatments were evaluated as predictors of clinical outcomes using univariate and multivariate analyses. Clinical remission was defined as no symptoms associated with microscopic colitis based on physician assessment and histologic remission was defined as no evidence of histological inflammation of microscopic colitis. RESULTS: Seventy-two patients with microscopic colitis were included in the study (28 with lymphocytic colitis and 44 with collagenous colitis). Non-steroidal anti-inflammatory drugs, proton pump inhibitors and selective serotonin reuptake inhibitors were used in 23 (31.9%), 14 (19.4%) and 15 (20.8%), respectively, at the time of diagnosis. Among 46 patients with adequate follow-up data, 25 (54.3%) patients achieved clinical remission. Response to budesonide (p = .0002) and achieving histologic remission (p = .0008) were associated with clinical remission on univariate analysis. On multivariate analysis, budesonide response (p = .0052) was associated with clinical remission (odds ratio 25.00, 95% confidence interval 2.63-238.10). Among 22 patients who underwent a follow-up colonoscopy, five patients (22.7%) achieved histologic remission. All patients with histologic remission maintained clinical remission without medication, whereas only two patients (11.8%) were able to discontinue medical therapy when histologic inflammation was present (p = .0002). CONCLUSIONS: In the present cohort of patients with microscopic colitis, a favourable response to budesonide was significantly associated with long-term clinical remission, and all patients achieving histological remission were able to maintain clinical remission without further medical therapy. Larger studies are required to confirm these findings.

Microscopic colitis related to food supplement containing turmeric: a review of 3 cases.

Microscopic colitis is a chronic inflammatory disorder of the colon characterized by microscopic changes in the intestinal lining. Turmeric, a commonly used spice, is generally regarded as beneficial for digestive and articular health thanks to its anti-inflammatory properties. No cases of microscopic colitis under a food supplement containing turmeric has been previously described in the literature. This article highlights 3 cases where the consumption of a specific turmeric-based supplement caused microscopic colitis. Each of them complained about profuse watery diarrhea shortly after initiating the food supplement containing turmeric. Ileo-colonoscopies with biopsies confirmed the diagnosis of microscopic colitis, with two cases classified as lymphocytic colitis and the third as collagenous colitis. Following the discontinuation of the supplement, all patients experienced a resolution of their symptoms within a few days. Subsequent control biopsies for the three patients confirmed the resolution of microscopic colitis.

Lymphocytic colitis can be transcriptionally divided into channelopathic and inflammatory lymphocytic colitis.

BACKGROUND: The pathobiology of the non-destructive inflammatory bowel disease (IBD) lymphocytic colitis (LC) is poorly understood. We aimed to define an LC-specific mucosal transcriptome to gain insight into LC pathology, identify unique genomic signatures, and uncover potentially druggable disease pathways. METHODS: We performed bulk RNA-sequencing of LC and collagenous colitis (CC) colonic mucosa from patients with active disease, and healthy controls (n = 4-10 per cohort). Differential gene expression was analyzed by gene-set enrichment and deconvolution analyses to identify pathologically relevant pathways and cells, respectively, altered in LC. Key findings were validated using reverse transcription quantitative PCR and/or immunohistochemistry. Finally, we compared our data with a previous cohort of ulcerative colitis and Crohn's disease patients (n = 4 per group) to distinguish non-destructive from classic IBD. RESULTS: LC can be subdivided into channelopathic LC, which is governed by organic acid and ion transport dysregulation, and inflammatory LC, which is driven by microbial immune responses. Inflammatory LC displays an innate and adaptive immunity that is limited compared to CC and classic IBD. Conversely, we noted a distinct induction of regulatory non-coding RNA species in inflammatory LC samples. Moreover, compared with CC, water channel and cell adhesion molecule gene expression decreased in channelopathic LC, whereas it was accentuated in inflammatory LC and associated with reduced intestinal epithelial cell proliferation. CONCLUSIONS: We conclude that LC can be subdivided into channelopathic LC and inflammatory LC that could be pathomechanistically distinct subtypes despite their shared clinical presentation. Inflammatory LC exhibits a dampened immune response compared to CC and classic IBDs. Our results point to regulatory micro-RNAs as a potential disease-specific feature that may be amenable to therapeutic intervention.

Clinical Implications of Microscopic Colitis Isolated to Polyps.

Microscopic colitis is generally identified on random colon biopsies performed for chronic diarrhea, but rarely incidental polyps have histologic features of microscopic colitis. We compared patients with polypoid microscopic colitis to control patients with conventional polyps to determine the implications of polypoid microscopic colitis.Medical records were searched for patients without prior or concurrent microscopic colitis who were found to have polypoid microscopic colitis. For each patient with polypoid microscopic colitis, one patient with conventional polyps was selected as a control. We reviewed the histologic features of each polypoid microscopic colitis specimen, and evaluated endoscopic and clinical findings for polypoid microscopic colitis patients and controls.Twenty-six patients with polypoid microscopic colitis were identified with histologic features of collagenous colitis in 8 patients (31%) and lymphocytic colitis in 18 patients (69%). Polypoid microscopic colitis was unifocal in 14 patients (54%) and multifocal in 12 patients (46%). Patients with polypoid microscopic colitis were older than control patients (median age = 60 years vs 66 years, P = .04). On follow-up 7 patients with polypoid microscopic colitis (33%) developed chronic diarrhea compared to 3 (12%) controls (P = .16). Of patients with follow-up biopsies, 1 patient with polypoid microscopic colitis (13%) and no control patients developed microscopic colitis (P = 1).Polypoid microscopic colitis may be identified in asymptomatic patients and most patients do not develop chronic diarrhea, but some patients with polypoid microscopic colitis develop diarrhea (33% vs 12% in controls) or conventional microscopic colitis on follow-up. Thus pathologists should distinguish polypoid microscopic colitis from conventional microscopic colitis but may inform clinicians of the uncertain association with chronic diarrhea to guide decisions regarding follow-up.

What do we know today about drug-induced microscopic colitis? A case of lymphocytic colitis on olmesartan.

Microscopic colitis is part of the differential diagnosis of chronic watery diarrhea. Colonoscopy discloses a normal looking mucosa, therefore its diagnosis is based on histology of colonic biopsies. Two main phenotypes are distinguished: collagenous colitis and lymphocytic colitis. A third entity, incomplete microscopic colitis or unspecified microscopic colitis has been reported in the literature. It affects preferentially women over 60 years of age and its association with certain drugs is increasingly established. In case of suspected drug-induced microscopic colitis, identification of the responsible drug is a key to management. After discontinuation of the suspected drug, the gold standard of treatment is budesonide both for induction and for maintenance in case of clinical relapse, as is often the case after discontinuation. Therapy with immunomodulators, biologics, or surgery is reserved for refractory forms of microscopic colitis after multidisciplinary consultation. Through the clinical case of colitis on olmesartan, we will review the latest recommendations on drug-induced microscopic colitis.

Celiac disease and risk of microscopic colitis: A nationwide population-based matched cohort study.

BACKGROUND: An association has been reported between celiac disease (CD) and microscopic colitis (MC). However, large, population-based cohort studies are rare. OBJECTIVE: To systematically examine the association between CD and MC in a large, nationwide cohort. METHODS: We conducted a nationwide population-based matched cohort study in Sweden of 45,138 patients with biopsy-verified CD (diagnosed in 1990-2016), 223,149 reference individuals, and 51,449 siblings of CD patients. Data on CD and MC were obtained from all (n = 28) pathology departments in Sweden. Adjusted hazard ratios (aHRs) were calculated using Cox regression. RESULTS: During follow-up, 452 CD patients and 197 reference individuals received an MC diagnosis (86.1 vs. 7.5 per 100,000 person-years). This difference corresponded to an aHR of 11.6 (95% confidence interval [CI] = 9.8-13.8) or eight extra MC cases in 1000 CD patients followed up for 10 years. Although the risk of MC was highest during the first year of follow-up (aHR 35.2; 95% CI = 20.1-61.6), it remained elevated even after 10 years (aHR 8.1; 95% CI = 6.0-10.9). Examining MC subtypes lymphocytic colitis (LC) and collagenous colitis (CC) separately, the aHR was 12.4 (95% CI = 10.0-15.3) for LC and 10.2 (95% CI = 7.7-13.6) for CC. MC was also more common before CD (adjusted odds ratio [aOR] = 52.7; 95% CI = 31.4-88.4). Compared to siblings, risk estimates decreased but remained elevated (CD and later MC: HR = 6.2; CD and earlier MC: aOR = 7.9). CONCLUSION: Our study demonstrated a very strong association of MC with CD with an increased risk of future and previous MC in CD patients. The magnitude of the associations underscores the need to consider the concomitance of these diagnoses in cases in which gastrointestinal symptoms persist or recur despite a gluten-free diet or conventional MC treatment. The comparatively lower risk estimates in sibling comparisons suggest that shared genetic and early environmental factors may contribute to the association between CD and MC.

Frequency And Risk Factors Of Microscopic Colitis As A Cause Of Chronic Watery Diarrhoea.

BACKGROUND: Microscopic colitis (MC) is one of the most underdiagnosed conditions leading to chronic watery diarrhoea in patients worldwide. This is the first study of this kind in Pakistan and we aimed to calculate the frequency as well as study the risk factors behind the disease. METHODS: This was a prospective cross-sectional study in a tertiary care hospital in Pakistan. A total of 58 participants with chronic watery diarrhoea who had normal colonoscopy were recruited for the study and biopsies were obtained for diagnosing MC. RESULTS: 2 participants out of 58 (3.4%) had biopsy proven microscopic colitis; one patient had a lymphocytic colitis variant and the other had a collagenous colitis variant. The average score based on the MC scoring system was 7.53 in the entire study group. The patient with lymphocytic colitis had a score of 06 while the patient with collagenous colitis had a score of 8. CONCLUSIONS: The frequency of microscopic colitis was found to be 3.4% of all cases of chronic watery diarrhoea. A link between MC and autoimmune diseases was also observed. However, we had a limited sample size and encouraged future studies to employ a larger sample size to get a multifaceted look at the disease process.

Estimating the optimum number of colon biopsies for diagnosing microscopic colitis: a systematic review.

Microscopic colitis (MC) is an inflammatory disease of the colon characterized by persistent watery, nonbloody diarrhea. Subtypes of MC include collagenous and lymphocytic MC. Microscopic examination of colon tissue is crucial to confirming the diagnosis because the colonic mucosa often appears normal during flexible sigmoidoscopy or colonoscopy. We aim to determine the optimal sites and minimum number of colon biopsies required to diagnose MC from published studies. We systematically searched PubMed, Web of Science, Scopus, and Cochrane databases from inception until October 2020 using the following keywords: microscopic, lymphocytic, collagenous, colitis, biopsy, and biopsies. We screened the search results for eligibility and extracted data from the included studies. We pooled the numbers of biopsies provided by each study to calculate the mean number of biopsies, SD, and SEM. We included three retrospective cohort studies with 356 patients (148 collagenous, 192 lymphocytic, and 16 mixed), and the total number of biopsies were 1854. The mean number of biopsies that were recommended by the included studies are 4, 4, and 9, respectively. The pooled mean ± SD is 5.67 ± 2.89. The included studies reported that biopsies from the ascending colon (AC) and descending colon (DC) had the highest diagnostic rates. To ensure a high level of certainty in diagnosing MC, a total of six biopsies should be taken from the AC and DC (3 AC and 3 DC). However, special care should be directed toward differentiating MC from other forms of colitis. In addition, detailed and comparative studies are needed to provide stronger recommendations to diagnose MC.

Mucosal and faecal neutrophil gelatinase-associated lipocalin as potential biomarkers for collagenous colitis.

BACKGROUND: Collagenous colitis (CC) is an inflammatory bowel disease where chronic diarrhoea is the main symptom. Diagnostic markers distinguishing between CC and other causes of chronic diarrhoea remain elusive. This study explores neutrophil gelatinase-associated lipocalin (NGAL) and its mRNA lipocalin2 (LCN2) as histological and faecal disease markers in CC. METHODS: NGAL/LCN2 were studied in colonic biopsies from CC patients before and during budesonide treatment using RNA sequencing (n = 9/group), in situ hybridization (ISH) (n = 13-22/group) and immunohistochemistry (IHC) (n = 14-25/group). Faecal samples from CC (n = 3-28/group), irritable bowel syndrome diarrhoea (IBS-D) (n = 14) and healthy controls (HC) (n = 15) were assayed for NGAL and calprotectin. RESULTS: NGAL/LCN2 protein and mRNA expression were upregulated in active CC vs HC, and vs paired samples of treated CC in clinical remission. IHC and ISH localized increased NGAL/LCN2 mainly to epithelium of active CC, compared to almost absence in HC and treated CC. In contrast, calprotectin was solely expressed in immune cells. Despite great individual differences, faecal NGAL was significantly increased in active CC compared to HC, IBS-D and treated CC and had high test sensitivity. Faecal calprotectin levels were variably increased in active CC, but the values remained below usual clinical cut-offs. CONCLUSION: NGAL/LCN2 is upregulated in the epithelium of active CC and reduced during budesonide-induced clinical remission to the level of HC and IBD-S. This was reflected in NGAL faecal concentrations. We propose NGAL as an IHC marker for disease activity in CC and a potential faecal biomarker discriminating CC from HC and IBS-D.

Gastrointestinal Infection and Risk of Microscopic Colitis: A Nationwide Case-Control Study in Sweden.

BACKGROUND AND AIMS: Gastrointestinal infections have been linked to changes in the composition and function of gut microbiome and development of inflammatory bowel diseases. We therefore sought to examine the relationship between gastroenteritis and risk of microscopic colitis (MC). METHODS: We conducted a case-control study of all adult patients with MC diagnosed between 1990 and 2016 in Sweden matched to up to 5 general population controls according to age, sex, calendar year, and county. Cases of MC were identified using Systematized Nomenclature of Medicine codes from the ESPRESSO (Epidemiology Strengthened by histoPathology Reports in Sweden) study, a cohort of gastrointestinal pathology reports from all 28 pathology centers in Sweden. We used logistic regression modeling to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). RESULTS: Through December of 2016, we matched 13,468 MC cases to 64,479 controls. The prevalence of previous diagnosed gastrointestinal infection was 7.5% among patients with MC, which was significantly higher than in controls (3.0%, Pcomparison < .001). After adjustment, gastroenteritis was associated with an increased risk of MC (aOR 2.63; 95% CI 2.42-2.85). Among specific pathogens, Clostridioides difficile (aOR 4.39; 95% CI 3.42-5.63), Norovirus (aOR 2.87; 95% CI 1.66-4.87), and Escherichia species (aOR 3.82; 95% CI 1.22-11.58), but not Salmonella species, were associated with an increased risk of MC. The association between gastrointestinal infections and risk of MC was stronger for collagenous subtype (aOR 3.23; 95% CI 2.81-3.70) as compared with lymphocytic colitis (aOR 2.51; 95% CI 2.28-2.76; Pheterogeneity = .005). The associations remained significant after adjustment for immune-mediated conditions and polypharmacy and when compared with unaffected siblings. CONCLUSION: In a nationwide study, we found that gastrointestinal infection, particularly Clostridioides difficile, is associated with an increased risk of subsequent MC. This study was approved by the Regional Ethics Committee, Stockholm, Sweden (Protocol no. 2014/1287-31/4).

Collagenous colitis in a child induced by chronic respiratory allergy: A case report.

INTRODUCTION: Collagen colitis (CC) is a microscopic colitis diagnosed by mucosal biopsy and is extremely rare in children. PATIENT CONCERNS: We reported a child with severe persistent diarrhea that could not be relieved with traditional diarrheal treatment. No abnormalities were found after multiple colonoscopies. DIAGNOSES: A significant increase in total IgE levels was found in the patient's blood. He had a history of mild chronic allergic rhinitis and slightly intermittent wheezing. However, we found that the child had a hyperallergic reaction to multiple respiratory antigens and had mild pulmonary dysfunction. Finally, colonoscopy with biopsy identified the diagnosis of CC. INTERVENTION: Considering that a respiratory allergic reaction was one of the causes of diarrhea, anti-allergic treatment was given to the child, and his severe diarrhea was soon relieved. Corticosteroid treatment was suggested to the patient, but his parents firmly refused steroid therapy. According to the patient's specific allergic reaction to mites, desensitization treatment was finally chosen for him. OUTCOMES: After 1 year of desensitization for dust mites, the patient's respiratory symptoms improved, total IgE levels decreased, autoantibodies declined, and diarrhea did not reoccur. Colonoscopy with biopsy showed a significant improvement in pathology. CONCLUSION: CC in children is rare, and childhood CC induced by a respiratory allergic reaction has not been previously reported. Therefore, this is a special case of CC in a patient who was cured with anti-allergy treatments and desensitization instead of steroid therapy.

Effects of subspecialty signout and group consensus on the diagnosis of microscopic colitis.

Microscopic colitis (MC) includes lymphocytic colitis (LC) and collagenous colitis (CC). Microscopic changes are required to establish these diagnoses. While criteria exist, interobserver variability has been reported previously. This has not been evaluated in the context of subspecialty signout (SSSO) or a consensus conference. We identified 133 colon biopsies diagnosed as LC, CC, MC, or normal but with mild changes insufficient for MC. All predated the introduction of SSSO at our institution. They were independently reviewed by three gastrointestinal (GI) pathologists. Cases lacking independent consensus were reviewed by the same pathologists in consensus conference to establish a final diagnosis. Individual diagnoses were compared with the consensus diagnoses, and consensus diagnoses were compared with original diagnoses made by GI and non-GI pathologists. Consensus diagnoses were normal (n = 34), LC (n = 57), and CC (n = 42). "Normal" was the diagnosis most commonly agreed upon independently (27/34 cases, P = 0.0073 versus LC, P = 0.0172 versus CC). The reviewing pathologists independently agreed with 80%, 80%, and 94% of consensus diagnoses (κ = 0.70, 0.69, and 0.91). The group consensus agreed with the diagnoses in 49 of 58 (84%) cases originally signed out by non-GI pathologists (κ = 0.77) and in 44 of 57 (77%) cases originally signed out by GI pathologists (κ = 0.63). Good interobserver agreement exists for MC, though whether GI subspecialty training improves agreement remains unclear. Group consensus may aid in diagnosis of difficult/borderline MC cases.

Collagenous colitis without diarrhoea at diagnosis - a follow up study.

OBJECTIVE: Chronic watery diarrhoea is a classical symptom of collagenous colitis (CC). However, in some cases, the typical histologic findings of CC can be found in patients without this symptom. In this study we have performed a follow up on patients with a confirmed histological diagnosis of CC without the typical symptom watery diarrhoea. PATIENTS AND METHODS: A structured medical record follow-up was performed on the subgroup of patients without watery diarrhoea but diagnosed with the typical CC histologic appearance in a previous study of microscopic colitis. RESULTS: At follow up after a median time of 8 years (range: 0.33-12 years), five of these fifteen patients developed bowel symptoms but only two developed characteristic CC symptoms with watery diarrhoea. CONCLUSION: The majority of patients without chronic watery diarrhoea at diagnosis remained free from this symptom during follow up and only in a few cases symptoms attributed to CC developed.

Diagnóstico y manejo de la colitis microscópica / Diagnosis and management of microscopic colitis

Microscopic colitis (MC) is a clinical condition characterized by chronic watery diarrhea, normal colonic mucosa and characteristic histological findings. It is composed of two main entities: collagenous colitis (CC) and lymphocytic colitis (LC). Its incidence has been increasing, currently accounting for between 8 to 16% of studies for chronic diarrhea. It is more frequent in elderly women and is strongly associated with other autoimmune disorders. Its pathogenesis is not very well understood, but it supposes the immune activation secondary to the exposure of the colonic mucosa to different luminal antigens, mainly drugs. Management includes suspension of the potential causative agent and the use of anti-diarrheal medications. Oral budesonide has proven to be effective in induction and maintenance of remission, but with a high rate of recurrence upon discontinuation. Immune-modulators drugs such as azatioprine and metrotrexate have been tested in patients dependent to corticoids with variable results. Antibodies against tumor necrosis factors (TNF) are under studies, with promising results.

La colitis microscópica (CM) es una condición clínica caracterizada por diarrea crónica acuosa con mucosa colónica normal y hallazgos histológicos característicos. Está compuesta por dos entidades principales: la colitis colágena (CC) y la colitis linfocítica (CL). Su incidencia ha ido en aumento, siendo en la actualidad la responsable del 8 a 16% de los casos por diarrea crónica. Es más frecuente en mujeres de edad avanzada con una fuerte asociación a otras enfermedades autoinmunes. Su etiopatogenia no es del todo conocida, pero se cree juega un rol la activación inmune secundaria a la exposición de la mucosa colónica a diferentes antígenos luminales, principalmente fármacos. Dentro del manejo se incluye la suspensión del potencial agente causal y el uso de fármacos antidiarreicos. La budesonida oral ha demostrado alta efectividad en la inducción y mantención de la remisión, pero con una alta tasa de recurrencia al suspenderla. Fármacos inmunomoduladores como azatioprina y metrotrexato se han probado en pacientes corticodependendientes con resultados variables. El uso de anticuerpos monoclonales anti factor de necrosis tumoral (TNF) se encuentra en estudio, con resultados prometedores.

[Microscopic Colitis]. / Mikroskopische Kolitis.

Microscopic colitis (MC) is still an underestimated cause of chronic, non-bloody watery diarrhea. It is typically manifested in elderly patients with a female predominance. The incidence of microscopic colitis has been increasing. The aetiology and pathophysiology remain unclear. Conditions associated with it include autoimmune diseases. There may be a genetic predisposition, as familial cases have been described. As implicated by the name microscopic colitis, the diagnosis is found by histological examination. There are mainly two subtypes, the lymphocytic colitis (LC) and the collagenous colitis (CC). Even if the condition's long-term course is benign, a chronic recurrent course of the symptoms is frequent. Due to the symptoms, there is an impairment of patient's health-related quality of life. A correct diagnosis and therapy is therefore mandatory. The aim of this paper is to create awareness for microscopic colitis.

Microscopic colitis: a population-based case series over a 9-year period in Northern Ireland.

AIM: We report clinicopathological experience of microscopic colitis (MC) in a population-based case series in Northern Ireland over a 9-year period. METHOD: The pathology laboratory information system within a large teaching centre serving two healthcare trusts was interrogated for cases coded between 2008 and 2016 as collagenous colitis (CC) or lymphocytic colitis (LC). Demographic, clinical and follow-up information was collected from healthcare records. RESULTS: A total of 326 new diagnoses of MC were identified, an average annual incidence of 6.7 per 100 000 population. The average annual incidence of CC and LC was 5.0 and 1.7 per 100 000 population, respectively. For coding reasons it is likely that LC data are incomplete. Of 191 cases diagnosed by specialist gastrointestinal pathologists, 141 patients had CC and 50 patients had LC. Both CC and LC predominantly involved women aged 60-79. Some 15% demonstrated endoscopic abnormalities. Endoscopic sampling protocols varied widely: 30% of individuals with CC and 32% of those with LC had the right and left colon sampled separately, with histology concordant in 95% of cases. Of the 191 cases, only one case (of LC) was refractory to treatment; the rest exhibited a clinical response. Only 35 patients had follow-up endoscopy and biopsies, and three of each diagnosis showed persistent disease on histology. CONCLUSION: Overall, CC and LC are benign conditions with similar demographics, clinical associations, management and outcomes. Separate sampling of the right and left colon is advised at colonoscopy if this diagnosis is being considered, but left colonic sampling, which can be performed at flexible sigmoidoscopy, will diagnose the vast majority of cases.

Pediatric Collagenous Gastritis and Colitis: A Case Series and Review of the Literature.

INTRODUCTION: Collagenous gastritis is a rare disease characterized by the subepithelial deposition of collagen bands. Two phenotypes of the disease have been described: a pediatric-onset and an adult-onset type. The adult-onset form is associated with collagenous colitis and autoimmune disorders. No effective treatment has been identified to date. OBJECTIVE: We aim to describe the clinical features and outcomes of patients in our cohort and provide a summary of published pediatric cases with collagenous gastritis and colitis reported to date to gather information that will contribute to improved knowledge of this rare condition. METHODS: A retrospective chart review of all patients with collagenous gastritis and/or colitis who were treated at the Royal Children's Hospital, Melbourne, was performed. A literature review was also conducted. RESULTS: A total of 12 cases of collagenous gastritis were reviewed. Three of 12 (25%) patients had associated collagenous colitis. The most common clinical presentation was iron deficiency anemia. Nine (75%) patients were followed up, and repeat endoscopies were performed in 8 (67%). Iron deficiency anemia resolved in all patients on oral iron supplementation. Histologic improvement was only identified in one patient with the adult phenotype who had been treated with oral corticosteroids and azathioprine. CONCLUSIONS: Collagenous gastritis is a rare condition in children. A small proportion of children develop features of the "'adult" phenotype at a very young age. Patients with collagenous gastritis require long-term follow-up and monitoring of their disease. Further randomized clinical trials are needed to establish an effective therapeutic strategy.