Human leucocyte antigen and TNFalpha polymorphism association in microscopic colitis

Clinicopathologic Characterization of Lymphocytic Colitis in the Pediatric Population

BACKGROUND

Lymphocytic colitis (LC) in the pediatric population has been associated with immune dysregulation.

METHODS

Single-center retrospective study of pediatric LC.

RESULTS

50 patients (35 female, 70%) with a median age of 12 years at diagnosis (interquartile range: 5.7-15.8) of LC were identified. At presentation, 11 patients (22%) had malnutrition, 16 (32%) had a known underlying immune dysregulation, 4 (8%) had celiac disease (CD), and none had a diagnosis of inflammatory bowel disease. The most common medications prior to diagnosis were non-steroidal anti-inflammatory drugs, proton pump inhibitor, and selective serotonin reuptake inhibitors (10% each). Colonic biopsies showed a median number of intraepithelial lymphocytes (IELs)/100 epithelial cells of 48 (range: 25-85), and only 10% of cases had neutrophilic cryptitis. Upper gastrointestinal tract findings included lymphocytic esophagitis (4%), and duodenal IELs without and with villous blunting (9% each) (n: 47). Ten patients (23%) had increased IELs in the terminal ileum (n: 43). Treatments including 5-ASA, budesonide, prednisone, and gluten-free diet improved symptoms in <50% of patients (n: 42), and all follow-up colonoscopies showed persistent LC (n: 13).

CONCLUSION

Our study supports the association of LC with immune-mediated conditions, most commonly celiac disease. Symptomatic improvement was seen in <50% of patients with none of the patients with repeat colonoscopy showing histologic improvement.

Microscopic colitis and risk of incident rheumatoid arthritis: A nationwide population-based matched cohort study

BACKGROUND

Microscopic colitis (MC) has been linked to several autoimmune conditions. Results from previous studies on the association with rheumatoid arthritis (RA) have been inconsistent.

AIM

To assess the risk of future RA in MC.

METHODS

We conducted a nationwide matched cohort study in Sweden of 8179 patients with biopsy-verified MC (diagnosed in 2007-2017), 36,400 matched reference individuals and 8202 siblings without MC, with follow-up until 2021. Information on MC was obtained from all of Sweden's regional pathology registers (n = 28) through the ESPRESSO cohort. Data on incident RA were collected from the National Patient Register. Using Cox regression, we calculated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).

RESULTS

During a median follow-up of 9.1 years (interquartile range = 6.7-11.7), 73 MC patients and 183 reference individuals from the general population were diagnosed with RA (99 vs. 55 events per 100,000 person-years), equivalent to one extra case of RA in 226 patients with MC followed for 10 years. These rates corresponded to an aHR of 1.83 (95% CI = 1.39-2.41). The aHR was highest during the first year of follow-up (2.31 [95% CI = 1.08-4.97]) and remained significantly elevated up to 5 years after MC diagnosis (aHR 2.16; 95% CI = 1.42-3.30). Compared to siblings, without MC, the aHR was 2.04 (95% CI = 1.18-3.56).

CONCLUSION

Patients with MC are at a nearly two-fold risk of developing RA compared to the general population. Knowledge of this increased risk may expedite evaluation for RA in patients with MC presenting with joint symptoms and/or arthralgia, thus preventing delay until RA diagnosis.

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.

Differential diagnosis of ulcerative colitis with increased diarrhea; collagenous colitis or irritable bowel syndrome? A case report

A 50-year-old man with a 20-year history of left-sided ulcerative colitis (UC) presented to our hospital with sudden onset of watery diarrhea. To this point, he had been treated with mesalazine 2.0 g/day for UC and had maintained remission. We considered that the UC had worsened. We immediately performed surveillance colonoscopy, which revealed a normal mucous membrane. The results of blood laboratory examinations were normal. Histopathology of colonic biopsies revealed new-onset collagenous colitis (CC), with a thickened subepithelial collagen band (SECB) and inactive UC. We herein report the importance of random colonic biopsies to diagnose CC even when the endoscopic appearance of the colon is normal in patients with inflammatory bowel disease with worsened diarrhea.

Rheumatologic Associations of Microscopic Colitis: A Narrative Review

Extra-intestinal manifestations are frequent complications of the classical inflammatory bowel diseases, Crohn's disease and ulcerative colitis. However, in addition to the classical diseases, there is a spectrum of conditions, often termed "microscopic colitis", in which extra-intestinal manifestations are less well described. Our objective was to review the literature regarding the extra-intestinal manifestations complicating microscopic colitis and describe the association with systemic autoimmune rheumatic diseases. A comprehensive search and review of peer-reviewed English-language and international journals and reports was completed based on key terms, including "microscopic colitis", "lymphocytic colitis", "collagenous colitis", "inflammatory bowel disease", "extraintestinal manifestations", and the specific disease associations utilizing the PubMed Central database and MEDLINE. A broad spectrum of rheumatologic manifestations has been reported in patients with microscopic colitis. The identification of rheumatoid arthritis and limited scleroderma as co-morbidities with microscopic colitis was noteworthy. Inflammatory arthropathy was frequently seen in microscopic colitis, usually preceding or occurring in conjunction with the onset of gastrointestinal symptoms. A variety of presentations of associated arthritis were reported: migratory, symmetric or asymmetric, peripheral or axial, oligoarticular or polyarticular, erosive or non-erosive. There was a high incidence of autoantibodies in these patients, supporting a potential autoimmune association. On the basis of these anecdotal reports, we would suggest development of a clinical registry to help define the incidence of extra-intestinal manifestations and systemic autoimmune rheumatic diseases among microscopic colitis patients to help elucidate shared predispositions, pathogenic mechanisms and therapeutic opportunities.

Lack of autoantibodies against collagen and related proteins in collagenous colitis

Introduction

Collagenous colitis (CC) is a common cause of chronic diarrhea and is characterized by a subepithelial thickened collagen layer in the colonic mucosa.

It shares many of the characteristics found in autoimmune diseases, but no autoantibodies have been identified. In CC, an imbalance in collagen turnover is evident. The purpose of the present study was to investigate whether any collagen-associated autoantibodies or other antibodies such as TPO and ASCA were present, and if levels of total IgE were increased.

Methods

Sera from women with active CC were analysed with ELISA for detection of autoantibodies against collagen type III and IV (Col III and IV), matrix metalloproteinase-9 (MMP-9), tissue inhibitors of metalloproteinase-1 (TIMP-1) and tenascin-C (TNC). Sera were also analysed for TPO, ASCA and total IgE. Healthy female blood donors served as controls. The cut-off value in the control group was defined as relative units > 97.5th percentile.

Results

Sixty-six women were included (mean age 60 years; range 31–74, mean disease duration 6 years; range 1–22). No autoantibody was significantly overexpressed in the CC population compared to controls. The mean disease duration was lower (p = 0.03) in the subjects who expressed collagen-associated autoantibodies (3.7 years; range 1–14), compared to those who did not (6.4 years; range 1–22). Treatment with budesonide was not associated with any of these autoantibodies.

Conclusion

No increased presence of the investigated antibodies could be found in the present study of CC. Neither could antibodies against ASCA or TPO, or elevated levels of IgE, be found. Consequently, no association was found between CC and these proteins, even though this may not be generalizable to other compounds in the collagen layer.

Pathogenesis of Microscopic Colitis: A Systematic Review

BACKGROUND

Whereas the exact aetiology of microscopic colitis [MC] remains unknown, a dysregulated immune response to luminal factors or medications is the most accepted pathogenesis hypothesis.

METHODS

We conducted a systematic review of the pathogenesis of MC. We applied the Joanna Briggs Institute methodologies and the PRISMA statement for the reporting of systematic reviews [PROSPERO Trial Identifier: CRD42020145008]. Populations, Exposure of interest, and Outcome [PEO] questions were used to explore the following topics in MC: 1] intestinal luminal factors; 2] autoimmunity; 3] innate immunity; 4] adaptive immunity; 5] extracellular matrix; 6] genetic risk factors; and 7] mechanism of diarrhoea. A search was done in PubMed, Embase, and Web of Science up to February 2020. A narrative description was performed explaining the findings for each aspect of MC aetiopathogenesis.

RESULTS

Thirty-eight documents provided evidence for PEO1, 100 for PEO2, 72 for PEO3 and 4, 38 for PEO5, 20 for PEO6, and 23 for PEO7. The majority of documents were cohorts, case reports, and case series, with a few case-control and some experimental studies. Consistency among data provided by different studies was considered to support pathogenetic hypotheses. MC is a multifactorial disease believed to involve innate and adaptive immune responses to luminal factors, genetic risk, autoimmunity, and extracellular matrix alterations, all contributing by varied mechanisms to watery diarrhoea.

CONCLUSIONS

This is the first systematic review on the aetiology of MC supporting the notion that MC is a multifactorial disease. However, high-profile studies are lacking, and most evidence derives from small heterogeneous studies.

Autoimmune diseases in microscopic colitis: A Danish nationwide case-control study

BACKGROUND

The association between autoimmune diseases and microscopic colitis remains uncertain.

AIMS

To describe the association between autoimmune diseases and microscopic colitis by using a matched case-control design based on nationwide registry data.

METHODS

All adult Danish patients with a diagnosis of microscopic colitis from 2001 to 2018 were identified from nationwide registries. Odds of autoimmune diseases were compared between cases with microscopic colitis and sex- and age-matched controls from the background population in a 1:10 ratio and evaluated by logistic regression calculating odds ratios (OR) with 95% confidence intervals (CI) adjusted for comorbidity. Analyses were stratified according to sex, age and the subtypes of lymphocytic and collagenous colitis.

RESULTS

We identified 15 597 cases with microscopic colitis and matched to 155 910 controls. In total, 3491 (22%) of patients with microscopic colitis had concomitant autoimmune disease compared to 16 521 (11%) of controls (OR, 2.46; 95% CI, 2.36-2.56). Adjusting for comorbidities reduced the OR to 2.09 (95% CI, 2.01-2.19). Analyses showed increased ORs with 16 different autoimmune diseases, particularly of gastrointestinal and endocrine origin, and connective tissue disorders. The highest ORs were for coeliac disease (OR = 10.15; 95% CI, 8.20-12.6), Crohn's disease (OR = 2.47; 95% CI, 2.10-2.91) and ulcerative colitis (OR = 6.73; 95% CI, 6.20-7.30). In stratified analyses younger age at diagnosis and collagenous colitis were associated with higher odds.

CONCLUSION

Using nationwide registry data, microscopic colitis was associated with a wide range of autoimmune diseases, especially of gastrointestinal origin. The results suggest an autoimmune predisposition to microscopic colitis.

Macroscopic to Microscopic - A Case of Crohn's Disease Progressing to Collagenous Colitis

The association between microscopic colitis (MC) and inflammatory bowel disease (IBD) is uncertain and infrequently reported. Rare cases in the literature consist of simultaneous MC and IBD, or progression of one condition to the other. We present a unique case of clinically and endoscopically diagnosed and successfully treated IBD that revealed MC on histology months later due to reappearance of diarrhea. Common pathophysiologic mechanisms, such as tumor necrosis factor α and T helper type 1 cells, may explain the MC and IBD relationship. During endoscopy, a prompt biopsy should be taken if suspicious for MC, thus decreasing the duration of patient's symptoms and saving healthcare costs.

Collagenous Gastritis in Children: Incidence, Disease Course, and Associations With Autoimmunity and Inflammatory Markers

Collagenous gastritis (CG), a rare disorder of unknown etiology, has been postulated to have immune-mediated mechanisms. We investigated (i) the incidence and prevalence of CG in a pediatric population; (ii) the clinical, endoscopic, and histologic characteristics of childhood-onset CG; and (iii) the evidence for autoimmunity and/or inflammatory activity in these patients.

Microscopic Colitis and Risk of Inflammatory Bowel Disease in a Nationwide Cohort Study

BACKGROUND & AIMS

Microscopic colitis shares pathogenetic mechanisms with inflammatory bowel disease (IBD). We studied the association between microscopic colitis and risk of incident IBD using data from a nationwide cohort study.

METHODS

We conducted a prospective cohort study of all adults who received a diagnosis of microscopic colitis from 1990 through 2017 in Sweden and risk of incident IBD. Cases of microscopic colitis (n= 13,957) were identified through Systematized Nomenclature of Medicine codes from the ESPRESSO (Epidemiology Strengthened by histoPathology Reports in Sweden) study, which included gastrointestinal pathology reports from all of Sweden's 28 centers. Individuals with microscopic colitis were matched to 5 general population controls (n = 66,820) and to unaffected siblings (n =13,943). Cox regression was used to estimate adjusted hazard ratio (aHRs) and 95% confidence intervals (CIs).

RESULTS

Through December of 2017, we identified 323 incident cases of ulcerative colitis (UC) and 108 incident cases of Crohn's disease (CD) in patients with microscopic colitis compared with 94 UC and 42 CD cases in population comparators. Mean times from diagnosis of microscopic colitis to diagnosis of CD was 3.3 ± 3.2 years and to diagnosis of UC was 3.2 ± 3.5 years. In multivariable models, microscopic colitis was associated with an aHR of 12.6 (95% CI 8.8-18.1) for CD, 17.3 (95% CI 13.7-21.8) for UC, and 16.8 (95% CI 13.9-20.3) for IBD. The 10-year absolute excess risks of CD and UC were 0.9 (95% CI 0.7-1.1) and 2.6 (95% CI 2.2-2.9) percentage points, respectively. In sensitivity analyses, comparing patients with microscopic colitis with their unaffected siblings, the aHRs of CD and UC were 5.4 (95% CI 3.2-9.2) and 9.4 (95% CI 6.4-13.8), respectively.

CONCLUSIONS

In a population-based study in Sweden, we found a significant increase in risk of incident IBD among patients with microscopic colitis. Future studies should focus on potential mechanisms underlying these observed associations.

Single-centre experience with anti-tumour necrosis factor treatment in budesonide-refractory microscopic colitis patients

Background

Microscopic colitis is an inflammatory bowel disease that causes chronic, watery diarrhoea. Microscopic colitis is usually effectively treated with budesonide, but some patients are refractory. Data on alternative treatments are sparse.

Aims

The purpose of this study was to retrospectively evaluate outcome of microscopic colitis patients receiving anti-tumour necrosis factor therapy at our centre.

Methods

Treatment results, including side effects, for all microscopic colitis patients receiving anti-tumour necrosis factor therapy were registered at week 12 and at end of follow-up. Clinical remission was defined as a mean of <3 stools and <1 watery stools/day/week and clinical response as a 50% reduction of mean stool frequency/day/week. Induction and maintenance treatment was either adalimumab or infliximab.

Results

The study cohort comprised 18 patients; mean age at diagnosis was 47 years (range 19-77). Ten and eight patients, respectively, received adalimumab and infliximab as first-line anti-tumour necrosis factor; seven patients received second-line anti-tumour necrosis factor due to non-response, loss of response or side effects. At week 12, 9/18 patients had achieved remission, 6/18 were responders and 3/18 were non-responders. Of the nine remission patients, 3/18 (16%) had long-lasting clinical remission post-induction therapy alone. Five patients (28%) (one first-line, four second-line anti-tumour necrosis factor) were in remission and one patient (6%) responded to maintenance treatment; follow-up was mean 22 (range 4-60) months. Six patients (33%) had minor, reversible side effects.

Conclusions

Over half of budesonide-refractory microscopic colitis patients can achieve clinical remission or response on anti-tumour necrosis factor agents. Prospective studies are mandatory to evaluate the efficacy and safety of anti-tumour necrosis factor treatments in budesonide-refractory microscopic colitis.

Expression Profiling of Inflammatory and Immunological Genes in Collagenous Colitis

BACKGROUND

Collagenous colitis [CC] is a common idiopathic cause of chronic watery diarrhoea. We investigated its pathogenesis by means of gene expression analysis.

METHODS

We analysed the expression of genes implicated in immunological and inflammatory pathways in paired colonic biopsies of histologically involved and uninvolved mucosa from five patients with histologically patchy CC, in pooled colonic biopsies of eight other patients with diffuse CC, and in pooled biopsies of eight normal controls. Analyses were performed with the Nanostring nCounter system. Expression ratios were generated and confirmed by quantitative reverse transcription PCR.

RESULTS

CC mucosa was characterized by enhanced expression of nitric oxide synthase 2; of matrix metalloproteinases 3 and 9 and tissue inhibitor of metalloproteinase 1, but not transforming growth factor β1; of mediators of T-helper 1 immunity including interleukins 12A [IL12A], 12B, IL12 receptor B1 and interferon γ; of immune mediators of the leukocyte immunoglobulin-like receptor subfamily B; and of multiple T cell cytokines and their receptors. The mitogen-activated protein kinase signalling pathway was unchanged. There were no increases in IL22, IL22RA2 or tumour necrosis factor α, which are reportedly elevated in chronic inflammatory bowel disease. In four of five patients with patchy CC, similar gene expression profiles were observed in histologically involved and uninvolved mucosa.

CONCLUSIONS

CC is characterized by altered expression of a limited repertoire of genes involved in nitric oxide synthesis, extracellular matrix remodelling, T-helper 1 immunity and immune modulation. The abnormal gene expression in patchy CC may be expressed in mucosa with and without histological disease manifestations.

Management of microscopic colitis: challenges and solutions

Microscopic colitis (MC) is a chronic inflammatory bowel disease characterized by nonbloody diarrhea in the setting of normal appearing colonic mucosa. MC has two main subtypes based on histopathologic features, collagenous colitis and lymphocytic colitis. Management of both subtypes is the same, with treatment goal of reducing the number of bowel movements and improving consistency. First-line treatment involves counseling the patient about decreasing their risk factors, like discontinuing smoking and avoiding medications with suspected association such as NSAIDs, proton pump inhibitor, ranitidine, and sertraline. Starting loperamide for immediate symptomatic relief is used as an adjunct to therapy with glucocorticoids. Budesonide is considered first-line treatment for MC given its favorable side effect profile and good efficacy, though relapse rates are high. Systemic glucocorticoids should be reserved to patients unable to take budesonide. In glucocorticoid refractory disease, medications that have been tried include cholestyramine, bismuth salicylate, antibiotics, probiotics, aminosalicylates, immunomodulators, and anti-tumor necrosis factor-alpha inhibitors. More research is needed for the creation of a systematic stepwise approach for relapsing and refractory disease.

Prevalence, Pathogenesis, Diagnosis, and Management of Microscopic Colitis

Microscopic colitis (MC), which is comprised of lymphocytic colitis and collagenous colitis, is a clinicopathological diagnosis that is commonly encountered in clinical practice during the evaluation and management of chronic diarrhea. With an incidence approaching the incidence of inflammatory bowel disease, physician awareness is necessary, as diagnostic delays result in a poor quality of life and increased health care costs. The physician faces multiple challenges in the diagnosis and management of MC, as these patients frequently relapse after successful treatment. This review article outlines the risk factors associated with MC, the clinical presentation, diagnosis and histologic findings, as well as a proposed treatment algorithm. Prospective studies are required to better understand the natural history and to develop validated histologic endpoints that may be used as end points in future clinical trials and serve to guide patient management.

Dense genotyping of immune-related loci identifies HLA variants associated with increased risk of collagenous colitis

OBJECTIVE

Collagenous colitis (CC) is a major cause of chronic non-bloody diarrhoea, particularly in the elderly female population. The aetiology of CC is unknown, and still poor is the understanding of its pathogenesis. This possibly involves dysregulated inflammation and immune-mediated reactions in genetically predisposed individuals, but the contribution of genetic factors to CC is underinvestigated. We systematically tested immune-related genes known to impact the risk of several autoimmune diseases for their potential CC-predisposing role.

DESIGN

Three independent cohorts of histologically confirmed CC cases (N=314) and controls (N=4299) from Sweden and Germany were included in a 2-step association analysis. Immunochip and targeted single nucleotide polymorphism (SNP) genotype data were produced, respectively, for discovery and replication purposes. Classical human leucocyte antigen (HLA) variants at 2-digit and 4-digit resolution were obtained via imputation from single marker genotypes. SNPs and HLA variants passing quality control filters were tested for association with CC with logistic regression adjusting for age, sex and country of origin.

RESULTS

Forty-two markers gave rise to genome-wide significant association signals, all contained within the HLA region on chromosome 6 (best p=4.2×10^-10 for SNP rs4143332). Among the HLA variants, most pronounced risk effects were observed for 8.1 haplotype alleles including DQ2.5, which was targeted and confirmed in the replication data set (p=2.3×10^-11; OR=2.06; 95% CI (1.67 to 2.55) in the combined analysis).

CONCLUSIONS

HLA genotype associates with CC, thus implicating HLA-related immune mechanisms in its pathogenesis.

Optimal management of collagenous colitis: a review

Collagenous colitis (CC) is an increasingly recognized cause of chronic inflammatory bowel disease characterized by watery non-bloody diarrhea. As a lesser studied inflammatory bowel disease, many aspects of the CC's natural history are poorly understood. This review discusses strategies to optimally manage CC. The goal of therapy is to induce clinical remission, <3 stools a day or <1 watery stool a day with subsequent improved quality of life (QOL). Antidiarrheal can be used as monotherapy or with other medications to control diarrhea. Budesonide therapy has revolutionized treatment and is superior to prednisone, however, the treatment is associated with high-relapse rates and the management of refractory disease is challenging. Ongoing trials will address the safety and efficacy of low-dose maintenance therapy. For those with refractory disease, case reports and case series support the role of biologic agents. Diversion of the fecal stream normalizes colonic mucosal changes and ileostomy may be considered where anti-tumor necrosis factor (TNF)-α agents are contraindicated. Underlying celiac disease, bile salt diarrhea, and associated thyroid dysfunction should be ruled out. The author recommends smoking cessation as well as avoidance of nonsteroidal anti-inflammatories as well as other associated medications.

Current concepts on microscopic colitis: evidence-based statements and recommendations of the Spanish Microscopic Colitis Group

BACKGROUND

Microscopic colitis (MC) is an underdiagnosed inflammatory bowel disease.

AIM

To develop an evidence-based clinical practice guide on MC current concepts.

METHODS

Literature search was done on the Cochrane Library, EMBASE and MEDLINE electronic databases, which were consulted covering the period up until March 2015. Work groups were selected for each of the reviewed topics, with the purpose of drafting the initial statements and recommendations. They subsequently underwent a voting process based on the Delphi method. Each statement/recommendation was accompanied by the result of the vote the level of evidence, and discussion of the corresponding evidence. The grade of recommendation (GR) using the GRADE approach was established for diagnosis and treatment recommendations.

RESULTS

Some key statements and recommendations are: advancing age increases the risk of developing MC, mainly in females. The symptoms of MC and IBS-D may be similar. If MC is suspected, colonoscopy taking biopsies is mandatory. Treatment with oral budesonide is recommended to induce clinical remission in patients with MC. Oral mesalazine is not recommended in patients with collagenous colitis for the induction of clinical remission. The use of anti-TNF-alpha drugs (infliximab, adalimumab) is recommended for the induction of remission in severe cases of MC that fail to respond to corticosteroids or immunomodulators, as an alternative to colectomy.

CONCLUSIONS

This is the first consensus paper on MC based on GRADE methodology. This initiative may help physicians involved in care of these patients in taking decisions based on evidence.

Contemporary methods for the diagnosis and treatment of microscopic colitis

Microscopic colitis is a common cause of chronic diarrhea. It is characterized by non-bloody watery diarrhea with macroscopically normal colonic mucosa. Its specific histological characteristics confirm the diagnosis. Two distinct histological forms can be identified, namely, collagenous colitis and lymphocytic colitis. In collagenous colitis, a thick colonic subepithelial collagenous deposit can be observed, whereas in lymphocytic colitis, a pronounced intraepithelial lymphocytic inflammation in the absence of a thickened collagen band can be identified. Microscopic colitis occurs more frequently in elderly females and its etiology is believed to be multifactorial, although smoking and consumption of several drugs have been identified as risks factors for the development of the disease. The treatment is based on avoiding the risks factors and administration of oral budesonide.

Microscopic colitis

Microscopic colitis (MC) is the common denominator for lymphocytic and collagenous colitis (CC). It is now recognized as a relatively frequent cause of diarrhea that equals the prevalence of inflammatory bowel disease. Patients are typically middle-aged women, but disease may occur at every age. Patients with MC report watery, non-bloody diarrhea in the absence of endoscopic and radiologic abnormalities. Lymphocytic colitis is characterized by an increased number of intraepithelial lymphocytes, and CC by a thickened subepithelial collagen band, whereas in both an increased mononuclear infiltration of the lamina propria is found. The pathogenesis of MC is largely unknown, but may relate to autoimmunity, adverse reactions to drugs or (bacterial) toxins, and abnormal collagen metabolism in the case of CC. Budesonide is so far the only drug that has proven efficacy in randomized controlled trials both for the induction and maintenance of remission. Patients who are nonresponsive, dependent or who experience side effects on budesonide may benefit from thiopurine or anti-TNF treatment, but these options are still experimental. The long-term prognosis of MC is good; it does not appear to predispose to malignancies and can in some cases be self-limiting. Further research and randomized clinical trials are required to expand our understanding of the natural course and the pathogenesis of MC.

New insights and challenges in microscopic colitis

Microscopic colitis (MC) is described as an inflammatory bowel disease characterized by chronic, bloodless diarrhea with normal or close to normal endoscopic findings. Histopathological examination reveals two subtypes: collagenous colitis (CC) and lymphocytic colitis (LC), which are indistinguishable clinically. The disease debuts typically in middle-aged patients, but can occur at all ages, including children. A female predominance is found in both CC and LC, but is not confirmed by others in LC. The etiology is unclear, but the disease has been assumed to be of autoimmune origin. However, several etiologies may render a microscopic inflammation in the mucosa; this is a common, universal reaction to a variety of irritants in contact with the intestinal lumen. Furthermore, some patients with a microscopic inflammation in their colonic mucosa have no symptoms, or are suffering from constipation or abdominal pain, rather than diarrhea. Recently, a discussion was initiated calling into question the overdiagnosing of symptoms and pointing out the danger of exacerbating people's perception of their ailments, of weakening their eligibility in health insurance, of overprescription of drugs, and thus the increasing cost to the society of health care. In the light of this discussion, this review will highlight histopathological and clinical features of MC, and discuss the diagnosis and management of this disease. Perhaps, the intestinal mucosa has no other mode by which to react than an inflammatory response, irrespective of the presence or absence of autoimmunity. Thus, to better identify and classify subgroups of MC, and to clarify and correctly handle the inflammatory changes, this field of research stands to benefit from a review of the results and experience gained to date.

Microscopic colitis: a review

AIM

In recent years, microscopic colitis has been increasingly diagnosed. This review was carried out to evaluate demographic factors for microscopic colitis and to perform a systematic assessment of available treatment options.

METHOD

Relevant publications up to December 2013 were identified following searches of PubMed and Google Scholar using the key words 'microscopic colitis', 'collagenous colitis' and 'lymphocytic colitis'. Two-hundred and forty-eight articles were identified.

RESULTS

The term microscopic colitis includes lymphocytic colitis and collagenous colitis. Both have common clinical symptoms but are well defined histopathologically. The clinical course is usually benign, but serious complications, including death, may occur. A peak incidence from 60 to 70 years of age with a female preponderance is observed. Although most cases are idiopathic, associations with autoimmune disorders, such as coeliac disease and hypothyroidism, as well as with exposure to nonsteroidal anti-inflammatory drugs and proton-pump inhibitors, have been observed. The incidence and prevalence of microscopic colitis is rising and good-quality epidemiological research is needed. Treatment is currently largely based on anecdotal evidence and on results from limited clinical trials of budesonide. Long-term follow-up of these patients is not well established.

CONCLUSION

The review synthesizes work on the definition of microscopic colitis and the relationship between collagenous and lymphocytic colitis. It reviews the international epidemiology and work on aetiology. In addition, it critically considers the efficacy of a range of treatments.

Diagnosis and management of microscopic colitis: current perspectives

Collagenous colitis and lymphocytic colitis, together constituting microscopic colitis, are common causes of chronic diarrhea. They are characterized clinically by chronic nonbloody diarrhea and a macroscopically normal colonic mucosa where characteristic histopathological findings are seen. Previously considered rare, they now have emerged as common disorders that need to be considered in the investigation of the patient with chronic diarrhea. The annual incidence of each disorder is five to ten per 100,000 inhabitants, with a peak incidence in 60- to 70-year-old individuals and a predominance of female patients in collagenous colitis. The etiology and pathophysiology are not well understood, and the current view suggests an uncontrolled mucosal immune reaction to various luminal agents in predisposed individuals. Clinical symptoms comprise chronic diarrhea, abdominal pain, fatigue, weight loss, and fecal incontinence that may impair the patient's health-related quality of life. An association is reported with other autoimmune disorders, such as celiac disease, thyroid disorders, diabetes mellitus, and arthritis. The best-documented treatment, both short-term and long-term, is budesonide, which induces clinical remission in up to 80% of patients after 8 weeks' treatment. However, after successful budesonide therapy is ended, recurrence of clinical symptoms is common, and the best possible long-term management deserves further study. The long-term prognosis is good, and the risk of complications, including colonic cancer, is low. We present an update of the epidemiology, pathogenesis, diagnosis, and management of microscopic colitis.

Genome-wide association study of celiac disease in North America confirms FRMD4B as new celiac locus

We performed a genome-wide association study (GWAS) of 1550 North American celiac disease cases and 3084 controls. Twelve SNPs, distributed across four regions (3p21.31, 4q27, 6q15, 6q25), were significantly associated with disease (p-value <1.0×10⁻⁷), and a further seven SNPs, across four additional regions (1q24.3, 10p15.1, 6q22.31, 17q21.32) had suggestive evidence (1.0×10⁻⁷ < p-value < 1.0×10⁻⁶). This study replicated a previous suggestive association within FRMD4B (3p14.1), confirming it as a celiac disease locus. All four regions with significant associations and two regions with suggestive results (1q24.3, 10p15.1) were known disease loci. The 6q22.31 and 10p11.23 regions were not replicated. A total of 410 SNPs distributed across the eight significant and suggestive regions were tested for association with dermatitis herpetiformis and microscopic colitis. Preliminary, suggestive statistical evidence for association with the two traits was found at chromosomes 3p21.31, 6q15, 6q25, 1q24.3 and 10p11.23, with future studies being required to validate the reported associations.

Microscopic colitis: Common cause of unexplained nonbloody diarrhea

Microscopic colitis (MC) is characterized by chronic, watery, secretory diarrhea, with a normal or near normal gross appearance of the colonic mucosa. Biopsy is diagnostic and usually reveals either lymphocytic colitis or collagenous colitis. The symptoms of collagenous colitis appear most commonly in the sixth decade. Patients report watery, nonbloody diarrhea of a chronic, intermittent or chronic recurrent course. With collagenous colitis, the major microscopic characteristic is a thickened collagen layer beneath the colonic mucosa, and with lymphocytic colitis, an increased number of intraepithelial lymphocytes. Histological workup can confirm a diagnosis of MC and distinguish the two distinct histological forms, namely, collagenous and lymphocytic colitis. Presently, both forms are diagnosed and treated in the same way; thus, the description of the two forms is not of clinical value although this may change in the future. Since microscopic colitis was first described in 1976 and only recently recognized as a common cause of diarrhea, many practicing physicians may not be aware of this entity. In this review, we outline the epidemiology, risk factors associated with MC, its etiopathogenesis, the approach to diagnosis and the management of these individuals.

Celiac disease and other autoimmune diseases in patients with collagenous colitis

BACKGROUND AND AIMS

Collagenous colitis (CC) is associated with autoimmune disorders. The aim of the present study was to investigate the relationship between CC and autoimmune disorders in a Swedish multicenter study.

METHODS

Patients with CC answered questionnaires about demographic data and disease activity. The patient's files were scrutinized for information about autoimmune diseases.

RESULTS

A total number of 116 CC patients were included; 92 women, 24 men, median age 62 years (IQR 55-73). In total, 30.2% had one or more autoimmune disorder. Most common were celiac disease (CeD; 12.9%) and autoimmune thyroid disease (ATD, 10.3%), but they also had Sjögren's syndrome (3.4%), diabetes mellitus (1.7%) and conditions in skin and joints (6.0%). Patients with associated autoimmune disease had more often nocturnal stools. The majority of the patients with associated CeD or ATD got these diagnoses before the colitis diagnosis.

CONCLUSION

Autoimmune disorders occurred in one-third of these patients, especially CeD. In classic inflammatory bowel disease (IBD), liver disease is described in contrast to CC where no cases occurred. Instead, CeD was prevalent, a condition not reported in classic IBD. Patients with an associated autoimmune disease had more symptoms. Patients with CC and CeD had an earlier onset of their colitis. The majority of the patients with both CC and CeD were smokers. Associated autoimmune disease should be contemplated in the follow-up of these patients.

Auto-antibodies and their association with clinical findings in women diagnosed with microscopic colitis

Background

Microscopic colitis (MC) is a disease manifested by diarrhoea and is divided into collagenous and lymphocytic colitis. The aetiology is unknown, but auto-immunity is suggested. Auto-antibodies have been only rarely examined in this entity. The aim of the study was to examine the prevalence of auto-antibodies, and to examine associations between the presence of antibodies and clinical findings.

Methods and Findings

Women with MC verified by biopsy and younger than 73 years, at any Department of Gastroenterology, in the district of Skåne, between 2002 and 2010 were invited to participate in this study. The patients were asked to complete both a questionnaire describing their medical history and the Gastrointestinal Symptom Rating Scale (GSRS). Blood samples were collected. Anti-nuclear antibodies (ANA), anti-neutrophil cytoplasmic antibodies (ANCA), anti-Saccharomyces cerevisiae antibodies (ASCA), and antibodies against glutamic acid decarboxylase (anti-GAD), islet antigens-like insulin 2 (anti-IA2), thyroid peroxidase (anti-TPO), and thyrotropin receptor (TRAK) were analysed. Of 240 women identified, 133 were finally included in the study, median age 63 (59–67) years. Apart from the MC diagnosis, 52% also suffered from irritable bowel syndrome, 31% from hypertension and 31% from allergy. The prevalence of ANA (14%), ASCA IgG (13%), and anti-TPO antibodies (14%) for these patients was slightly higher than for the general population, and were found together with other concomitant diseases. Patients had more of all gastrointestinal symptoms compared with norm values, irrespective of antibody expression.

Conclusions

Women with MC have a slightly increased prevalence of some auto-antibodies. These antibodies are not associated with symptoms, but are expressed in patients with concomitant diseases, obscuring the pathophysiology and clinical picture of MC.

Clinical presentation, diagnosis, pathogenesis and treatment options for lymphocytic colitis (Review)

Lymphocytic colitis (LC) is characterized by chronic or relapsing non-bloody watery diarrhea and a macroscopically normal colon. However, histopathological examination of colonic biopsy samples reveals an increased intraepithelial infiltration of lymphocytes (≥20/100 enterocytes), and increased inflammatory cells within the lamina propria, but with a normal mucosal architecture. The reported prevalence of LC varies from 14.2 to 45 per 100,000 individuals, while its reported incidence is between 0.6 and 16 per 100,000 individuals. LC has a high rate of spontaneous symptomatic remission and is not associated with an increased risk of colon cancer or inflammatory bowel disease. The diagnosis is based on the histopathological findings. The density of colonic chromogranin A-positive cells provides an effective diagnostic tool with high sensitivity and specificity in both the right and left colon. Gastrointestinal infections, drugs, and/or autoimmunity may trigger chronic colonic low-grade inflammation. Colonic nitric oxide, serotonin and peptide YY (PYY) cell densities are markedly increased in patients with LC. It has been hypothesized that the low-grade inflammation in LC through the endocrine-immune axis causes this increase. It has been postulated further that these abnormalities in the neuroendocrine system of the colon are responsible for the diarrhea observed in patients with LC. The benign course and rate of spontaneous remission of LC denotes that drugs with severe side-effects should be avoided if possible. The drug cost and drug coverage may also be limiting factors for some patients. These aspects should be taken into account when making decisions regarding treatment options.

Human leukocyte antigen DQ2/8 prevalence in non-celiac patients with gastrointestinal diseases

AIM: To investigate the prevalence of human leukocyte antigen (HLA) DQ2/8 alleles in Southern Italians with liver and gastrointestinal (GI) diseases outside of celiac disease.

METHODS: HLA DQ2/8 status was assessed in 443 patients from three ambulatory gastroenterology clinics in Southern Italy (University of Federico II, Naples, Loreto Crispi Hospital, Ruggi D’Aragona Hospital, Salerno). Patients were grouped based on disease status [pre-post transplant liver disease, esophageal/gastric organic and functional diseases, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD)] and DQ2/8 alleles, which correspond to a celiac disease genetic risk gradient. Subject allele frequencies were compared to healthy Italian controls.

RESULTS: One hundred and ninety-six out of four hundred and forty-three (44.2%) subjects, median age 56 years and 42.6% female, were DQ2/8 positive. When stratifying by disease we found that 86/188 (45.7%) patients with liver disease were HLA DQ2/8 positive, 39/73 (53.4%) with functional upper GI diseases and 19/41 (46.3%) with organic upper GI diseases were positive. Furthermore, 38/105 (36.2%) patients with IBS and 14/36 (38.9%) with IBD were HLA DQ2/8 positive (P = 0.21). Compared to healthy controls those with functional upper GI diseases disorders had a 1.8 times higher odds of DQ2/8 positivity. Those with liver disease had 1.3 times the odds, albeit not statistically significant, of DQ2/8 positivity. Both those with IBS and IBD had a lower odds of DQ2/8 positivity compared to healthy controls.

CONCLUSION: The proportion of individuals HLA DQ2/8 positive is higher in those with liver/upper functional GI disease and lower in IBS/IBD as compared to general population estimates.

Microscopic colitis: epidemiology, pathophysiology, diagnosis and current management-an update 2013

Microscopic colitis is a common cause of chronic diarrhea. Over the last years the incidence and the prevalence of microscopic colitis are rising and this rise is largely attributed to a rising awareness, and concomitantly an increasing number of diagnoses are made. Patients with microscopic colitis report watery, nonbloody diarrhea of chronic, intermittent, or chronic recurrent course. Following an unremarkable physical examination the diagnosis of microscopic colitis is made by colonoscopy, which shows essentially a normal colonic mucosa. Biopsies taken during the colonoscopy procedure will then finally establish the correct diagnosis. Histological workup can then confirm a diagnosis of microscopic colitis and can distinguish the two distinct histological forms, namely, collagenous colitis and lymphocytic colitis. Presently both forms are diagnosed and treated in the same way; thus the description of the two forms is not of clinical value, though this may change in future. Depending on the patients age and gender 10-30% of patients investigated for chronic diarrhea will be diagnosed with microscopic colitis if biopsies are taken. Microscopic colitis is most common in older patients, especially in female patients and is frequently associated with autoimmune disorders and the consumption of several drugs. This review summarizes the present knowledge of the epidemiology, the pathophysiology, and the diagnosis of microscopic colitis and discusses the former and the present treatment options.

Lymphocytic colitis is associated with increased pro-inflammatory cytokine profile and up regulation of prostaglandin receptor EP4

Microscopic colitis (MC) is comprised of two entities, lymphocytic (LC) and collagenous colitis. Up to 20% of patients with chronic diarrhea that have a normal appearing colonoscopy will be diagnosed with MC. Since MC was first described less than 40 years ago, little is known about the mechanisms involved in disease pathogenesis. Nonsteroidal anti-inflammatory drugs are associated with an increased risk of MC and some reports suggest a dysregulation in prostaglandin production. Recent genome wide screens have found an association between prostaglandin receptor EP4 expression and inflammatory bowel disease; however, EP4 expression has never been studied in MC. The aim of this study was to assess colonic mucosal inflammatory cytokine profiles in patients with LC and to assess expression of the prostaglandin receptor EP4. Colonic mucosal biopsies were obtained from patients undergoing colonoscopy for investigation of diarrhea and in those undergoing colon cancer screening. Following histological assessment, expression of cytokines and the prostaglandin receptor EP4 was analyzed using real-time reverse transcriptase-PCR and immunohistochemistry. Patients with LC had markedly increased mRNA expression for TNF-α, IFN-γ and IL-8 compared to normal controls (p<0.001). No significant differences were noted for IL-1β, IL-4, IL-10 or IL-12/23. Interestingly, those with LC had increased EP4 receptor expression, which positively correlated with increased TNF-α expression. This is the first report to demonstrate that LC is associated with increased TNF-α, INF-γ and IL-8 concurrent with a marked up-regulation of EP4. These findings add to our knowledge on the pathogenesis of LC and may give rise to possible new therapeutic and/or diagnostic tools in the management of MC.

Microscopic colitis: Current status, present and future challenges: statements of the European Microscopic Colitis Group

Microscopic colitis (MC) is an inflammatory bowel disease presenting with chronic, non-bloody watery diarrhoea and few or no endoscopic abnormalities. The histological examination reveals mainly two subtypes of MC, lymphocytic or collagenous colitis. Despite the fact that the incidence in MC has been rising over the last decades, research has been sparse and our knowledge about MC remains limited. Specialists in the field have initiated the European Microscopic Colitis Group (EMCG) with the primary goal to create awareness on MC. The EMCG is furthermore a forum with the intention to promote clinical and basic research. In this article statements and comments are given that all members of the EMCG have considered being of importance for a better understanding of MC. The paper focuses on the newest updates in epidemiology, symptoms and diagnostic criteria, pathophysiology and highlights some unsolved problems. Moreover, a new treatment algorithm is proposed on the basis of new evidence from well-designed, randomized control trials.

The Differential Diagnosis of Colitis in Endoscopic Biopsy Specimens: A Review Article

Context.—A variety of inflammatory disorders may affect the colon, with widely differing clinical outcomes and management. These conditions encompass a spectrum of acute and chronic conditions.

Objective.—Review the pathology of the major colitides and highlight the most diagnostically useful features.

Data Sources.—Review of recent literature supplemented with personal experience in the field of gastrointestinal pathology.

Conclusions.—The etiologies associated with the various types of colitis are diverse and the range of histologic changes is somewhat limited. Nevertheless, the combination of clinical and endoscopic data coupled with histopathology allows for accurate classification in the majority of cases.

Biopsy interpretation of colonic biopsies when inflammatory bowel disease is excluded

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

Lymphocytic colitis and collagenous colitis: a review of clinicopathologic features and immunologic abnormalities

Lymphocytic colitis (LC) and collagenous colitis (CC), 2 histologic forms of microscopic colitis, were recognized as rare disease entities 4 decades ago. An increasing body of evidence accumulated in the past 40 years reveals increasing incidence and prevalence rates, a wide spectrum of clinical presentations, and several histologic variants. Although several recent randomized clinical trials confirmed the efficacy of oral budesonide in treating LC and CC, disease relapse after a short-duration treatment is common. Despite their common clinical presentations and well-defined histologic diagnostic criteria, there are only few studies on the immunologic abnormalities in colonic tissue. The aim of this review is to (1) familiarize the pathologists in general practice with histomorphology of LC and CC, including the rare histologic variants and the clinical implication associated with these 2 diagnoses, (2) summarize the data from recent randomized clinical trials of oral budesonide, and (3) review immunological studies on colonic tissue. Overall, immunologic abnormalities of colonic tissue seem to explain for the histomorphologic features and the clinical symptomatology of LC and CC. Advances in the understanding of the underlying immunologic abnormalities in the colonic tissue may help develop novel and effective therapies for these 2 diseases.

Cytokine gene polymorphism in microscopic colitis association with the IL-6-174 GG genotype

OBJECTIVES

Microscopic colitis (MC) is a chronic inflammatory disease with unknown pathogenesis. Very little is known about polymorphisms in the cytokine genes in MC. We have investigated the occurrence of well-characterized polymorphisms of interleukins (IL-6, IL-1β, IL-1 receptor antagonist, IL-10) and CD14 in MC. We also determined the serum IL-6 levels.

METHODS

We genotyped 81 patients with MC and 178 controls for polymorphisms of IL-6-174, IL-1β-511, IL-1β-3953, IL-1 receptor antagonist, IL-10-1082 and CD14-159. Serum concentration of IL-6 was measured in 72 patients.

RESULTS

Genotype GG of IL-6-174 was more prevalent in MC compared with the controls (P=0.030; odds ratio: 1.941; confidence interval: 1.078-3.495), and the frequency of allele G of IL-6-174 was higher in MC (0.55 vs. 0.47; P=0.036; odds ratio: 1.514; confidence interval: 1.041-2.203). However, after correction for multiple comparisons, the difference became nonsignificant. IL-6 genotype and the serum IL-6 concentration showed no association. The concentration of IL-6 was higher in patients with collagenous colitis than in those with lymphocytic colitis (median 1.73 vs. 1.34 pg/ml, P=0.011). No association between polymorphisms of other cytokine genes and MC was seen.

CONCLUSION

The IL-6-174 gene polymorphism has a possible association with MC, as the IL-6 GG genotype was more frequent in patients with the disease. As this genotype may be linked with an enhanced IL-6 production, we speculate that this polymorphism can influence the pathogenesis of MC by evoking a proinflammatory bias in the mucosal cytokines. The enhanced concentration of IL-6 in collagenous colitis compared with lymphocytic colitis supports a difference in the pathogenetic mechanisms between the two subgroups of MC.

Gastroduodenal mucosa in microscopic colitis

BACKGROUND

We have assessed gastroduodenal, endoscopical and histopathological findings in a series of patients with microscopic colitis (MC).

METHODS

We studied 75 patients with MC, 27 with collagenous colitis (CC) and 48 with lymphocytic colitis (LC), and 60 controls. Data of endoscopical findings were collected and biopsies were assessed.

RESULTS

Helicobacter pylori infection rate was 15% in MC and 28% in the controls (p = 0.088). Age at diagnosis of MC was higher in H. pylori positive than negative patients (63.4 ± 9.6 vs. 54.4 ± 13.1 years; p = 0.034). Gastric endoscopic erosions were more prevalent in CC than in LC (25.9% vs. 6.2%; p = 0.030) and associated with thick body glands and antral predominance of gastritis in H. pylori positive patients. Rates of focal gastritis (5.6% vs. 6.9%) and lymphocytic gastritis (5.6% vs. 10%) were similar in MC and controls. LC was associated with gastric epithelial lymphocytosis and lymphocytic gastritis. Fifteen patients (20%) had celiac disease.

CONCLUSIONS

Unlike LC, CC is associated with endoscopic erosions, likely related with the high acid secretion capacity as indicated by the ample body glands and antral predominance of gastritis in H. pylori associated cases of CC. The presence of some divergent gastroduodenal features in LC and CC, and in comparison with those reported in inflammatory bowel disease (IBD), supports the concept that these two conditions differ not only from IBD but also from each other. The findings also suggest the presence of pathogenetic links between colorectal and gastroduodenal abnormalities.

Microscopic colitis -- a common cause of diarrhoea in older adults

Diarrhoeal diseases are common in older populations and often markedly affect their quality of life. Although there are numerous potential causes, microscopic colitis (MC) is increasingly recognised as a major diagnostic entity in older individuals. MC is comprised of two distinct histological forms - collagenous colitis and lymphocytic colitis, both of which frequently occur in older populations. Recent studies suggest that between 10 and 30% of older patients investigated for chronic diarrhoea with an endoscopically normal appearing colon will have MC. It is unclear why MC is more common in older populations, but it is associated with both autoimmune disorders and several drugs that are commonly used by seniors. A definitive diagnosis can only be made with colonic biopsies. Since MC was first described in 1976 and only recently recognised as a common cause of diarrhoea, many practising physicians may not be aware of this entity. In this review, we outline the epidemiology, risk factors associated with MC, its pathophysiology, the approach to diagnosis and the management of these individuals.

Microscopic colitis: an update

Microscopic colitis (MC) causes chronic diarrhea, abdominal cramping, nausea, and weight loss. Colonic mucosa appears normal on endoscopy; however, biopsies show abnormalities such as intraepithelial lymphocytosis in lymphocytic colitis, and a thickened subepithelial collagen band in collagenous colitis. Epidemiologic data demonstrates that MC is a more common cause of diarrhea than previously shown. Although the etiology of this condition is unclear, certain well-defined risk factors exist. Recently there has been more research on the pathophysiology of MC, and studies on treatment have demonstrated budesonide to be most effective, although other treatments also hold promise.

Diagnosis and management of microscopic colitis

Microscopic colitis, comprising collagenous and lymphocytic colitis, is characterized clinically by chronic watery diarrhea, and a macroscopically normal colonic mucosa where diagnostic histopathological features are seen on microscopic examination. The annual incidence of each disorder is 4-6/100,000 inhabitants, with a peak incidence in 60-70-year-old individuals and a noticeable female predominance for collagenous colitis. The etiology is unknown. Chronic diarrhea, abdominal pain, weight loss, fatigue and fecal incontinence are common symptoms, which impair the health-related quality of life of the patient. There is an association with other autoimmune disorders such as celiac disease, diabetes mellitus, thyroid disorders and arthritis. Budesonide is the best-documented short-term treatment, but the optimal long-term strategy needs further study. The long-term prognosis is good and the risk of complications including colonic cancer is low.