Review article: Microscopic colitis--lymphocytic, collagenous and 'mast cell' colitis

Is mastocytic colitis a specific clinical-pathological entity?

The number of intestinal mast cells (MC) is increased in several types of colitis, but the mucosa of patients with chronic non-bloody diarrhea has not been studied. The current study sought to determine the relationship between MC counts and degranulation and the severity of symptoms in patients with chronic loose stools. Following a negative laboratory workup for the most common causes of chronic diarrhea, patients with chronic non-bloody loose stools were included in the study. Patients with macroscopic evidence of inflammation or organic disease were excluded after endoscopy with biopsies. Biopsies from the 179 patients in the study were stained with hematoxylin and eosin and anti-CD117 c-kit antibodies. Immunohistochemistry was used to assess the degree of MC degranulation. Out of the 179 patients, 128 had normal histologic findings suggestive of irritable bowel syndrome and were used as controls. Twenty-four presented with abnormally high MC counts (≥40 MC x HPF), 23 with ≥20 intraepithelial lymphocytes x HPF suggesting lymphocytic colitis, and 4 had both (≥40 MC and ≥20 intraepithelial lymphocytes x HPF). In the patients with high MC counts, figures were significantly higher in the right colon versus the left colon (p=0.016), but degranulation did not differ in the right versus the left colon (p=0.125). No age or sex-related difference was observed (p=0.527 and p=0.859 respectively). The prevalence of abdominal pain and bloating did not differ in the three groups (p=0.959 and p=0.140, respectively). Patients with lymphocytic colitis (p=0.008) and those with high MC counts (p=0.025) had significantly higher evacuation rates compared to controls. There was no difference between these two groups (p=0.831). Mast cell degranulation was not associated with the number of evacuations, abdominal pain, or bloating (p=0.51; p=0.41; p=0.42, respectively). The finding that a significantly higher number of evacuations was linked to increased MC in the colonic mucosa of a subset of patients with otherwise normal laboratory and endoscopic findings suggests that "mastocytic colitis" may be a new clinical-pathological entity responsible for chronic non-bloody diarrhea. Prospective studies with a larger number of patients, as well as endoscopic and histological follow-up, are needed to confirm this hypothesis.

Increased Mast Cell Counts and Degranulation in Microscopic Colitis

OBJECTIVES

Microscopic colitis (MC) is characterized by chronic diarrhea, normal colonoscopy findings, and mucosal inflammation in colonic biopsies and can be classified as collagenous colitis (CC) or lymphocytic colitis (LC). However, the pathogenesis of MC is largely unknown. In this study, we aimed to study mast cell counts and activation in MC.

METHODS

We investigated 64 biopsy samples from the surgical pathology database of Indiana University Health, which met the diagnostic criteria for CC or LC along with 20 control samples collected from 2014 to 2015. The specimens were used for the quantification of mast cells by examining the presence of intracellular and extracellular tryptase by immunohistochemistry.

RESULTS

In the lamina propria, the mast cell count was higher in both CC and LC groups than the control (mean highest count, 39/high-power field (HPF) vs. 30/HPF vs. 23/HPF; P < 0.01). Extracellular tryptase was present in 10% of control subjects as compared to 41% of CC (P < 0.01). Extracellular tryptase was present in 10% of control subjects as compared to 41% of CC (P < 0.01). Extracellular tryptase was present in 10% of control subjects as compared to 41% of CC (.

CONCLUSIONS

The increased mast cell count and degranulation are identified in MC, suggesting that mast cell activation might be involved in the pathogenesis of MC.

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.

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.

Demographic and Dietary Associations of Chronic Diarrhea in a Representative Sample of Adults in the United States

OBJECTIVES

No studies to date estimate the prevalence of chronic diarrhea in the United States using the Bristol stool form scale (BSFS). This study aims to report the prevalence and associated factors of chronic diarrhea using BSFS scores in a nationally representative sample of US adults.

METHODS

We identified 5,246 adult participants (age ≥20 years) who completed the bowel health questionnaire in the National Health and Nutrition Examination Survey 2009-2010 data set. Chronic diarrhea was defined as type 6 or 7 rating on the BSFS (mushy or liquid consistency) as the "usual or the most common stool type." Co-variables included age, race, education, poverty income ratio, body mass index, number of medications, feeling depressed, physical activity, and dietary intake. Prevalence estimates and prevalence odds ratios (PORs) were analyzed in adjusted multivariable models using appropriate sampling weights.

RESULTS

We found a prevalence of chronic diarrhea of 6.6% (95% confidence interval (CI) 5.8, 7.4) in the nationally representative data set. High daily carbohydrate intake (POR 1.56, 95% CI 1.02, 2.40), obesity (POR 2.04, 95% CI 1.44, 2.89), feeling depressed (POR 1.84, 95% CI 1.21, 2.80), older age (POR 1.02, 95% CI 1.01, 1.02), and female sex (POR 1.68, 95% CI 1.28, 2.21) were positively correlated with chronic diarrhea. Non-Hispanic White race (POR 0.49, 95% CI 0.29, 0.81) and higher education (POR 0.60, 95% CI 0.43, 0.83) were negatively correlated with chronic diarrhea.

CONCLUSIONS

In a nationally representative sample of the US adults, the prevalence of chronic diarrhea was 6.6%. We identified demographic, lifestyle, and dietary factors associated with chronic diarrhea.

Farnesoid X Receptor Expression in Microscopic Colitis: A Potential Role in Disease Etiopathogenesis

Introduction

Microscopic colitis (MC) is a chronic inflammatory bowel disease with unclear etiology. Bile acid (BA) malabsorption has been described in MC patients. Farnesoid X receptor (FXR) is the main BA receptor; FXR-mediated mechanisms prevent the noxious effects of BA accumulation, preserving the integrity of the intestinal epithelial barrier and preventing intestinal inflammation.

Aim

Our aim was to describe the expression of FXR in patients with MC.

Methods

Archival formalin-fixed paraffin-embedded samples from the terminal ileum, right and left colon were obtained from patients with MC and matched controls. Immunohistochemistry was performed and nuclear FXR expression scored in a semi-quantitative way.

Results

169 formalin-fixed paraffin-embedded samples from 35 patients with MC and 31 controls were retrieved. There was a significant reduction of FXR expression in patients with MC versus controls both in the right colon (moderate-strong FXR expression: 21.1 vs. 64.3%; p = 0.003) and left colon (moderate-strong FXR expression: 8.3 vs. 38.7%; p = 0.027). No significant differences in FXR expression were observed in the ileum of patients with MC (moderate-strong FXR expression: 76.9 vs. 90.9%; p = 0.5). We found no difference in FXR expression between the two types of MC. No association between the degree of lymphocyte infiltration or the thickness of collagen band and FXR expression was found.

Conclusions

Patients with MC present a significantly lower expression of FXR in the colon. This could render colonic epithelial cells more susceptible to the deleterious effects of BA, contributing to disease pathogenesis and symptoms in MC.

Differences in the socio-economic distribution of inflammatory bowel disease and microscopic colitis

AIM

Inflammatory bowel disease (IBD) and microscopic colitis are characterized by different geographical distributions across the USA. In this cross-sectional study we utilized demographic and socio-economic information associated with individual ZIP codes to further delineate the epidemiological characteristics of the two diseases.

METHOD

A total of 813 057 patients who underwent colonoscopy between 2008 and 2014 were extracted from an electronic database of histopathology reports. The prevalence of patients with IBD or microscopic colitis was expressed as percentage of the population associated with specific demographic (age, sex, ethnicity) and socio-economic characteristics (population size, housing value, annual income, tertiary education).

RESULTS

Both diseases were more common among subjects from ZIP codes with predominantly White residents and less common among subjects from ZIP codes with predominantly non-White residents such as Black, Hispanic and Asian. These ethnic variations were more pronounced in microscopic colitis than IBD. Markers of affluence, such as average residential house value and annual income, were positively associated with IBD and negatively with microscopic colitis. The prevalence of both diseases was positively correlated with tertiary education.

CONCLUSION

The occurrence of both IBD and microscopic colitis is influenced by environmental risk factors. The differences in the demographic, ethnic and socio-economic distributions of the two diseases suggest that different sets of risk factors affect the two diseases and that their aetiology is unrelated.

Towards a new paradigm of microscopic colitis: Incomplete and variant forms

Microscopic colitis (MC) is a chronic inflammatory bowel disease that has emerged in the last three decades as a leading cause of chronic watery diarrhoea. MC classically includes two main subtypes: lymphocytic colitis (LC) and collagenous colitis (CC). Other types of histopathological changes in the colonic mucosa have been described in patients with chronic diarrhoea, without fulfilling the conventional histopathological criteria for MC diagnosis. Whereas those unclassified alterations remained orphan for a long time, the use of the term incomplete MC (MCi) is nowadays universally accepted. However, it is still unresolved whether CC, LC and MCi should be considered as one clinical entity or if they represent three related conditions. In contrast to classical MC, the real epidemiological impact of MCi remains unknown, because only few epidemiological studies and case reports have been described. MCi presents clinical characteristics indistinguishable from complete MC with a good response to budesonide and cholestiramine. Although a number of medical treatments have been assayed in MC patients, currently, there is no causal treatment approach for MC and MCi, and only empirical strategies have been performed. Further studies are needed in order to identify their etiopathogenic mechanisms, and to better classify and treat MC.

Systematic review with meta-analysis: diagnostic overlap of microscopic colitis and functional bowel disorders

BACKGROUND

Microscopic colitis shares certain common clinical manifestations with functional bowel disorders, especially diarrhoea-dominant irritable bowel syndrome (IBS) and functional diarrhoea. However, the exact relationship between microscopic colitis and functional bowel disorders has not been systematically assessed.

AIM

To conduct a systematic review and meta-analysis on the diagnostic overlap between functional bowel disorders and microscopic colitis.

METHODS

We searched MEDLINE, EMBASE and SCOPUS databases, as well as the abstract books of the major gastroenterology meetings, to investigate the prevalence of microscopic colitis among patients with functional bowel disorders (considering all subtypes of both disorders) and vice versa. Data were pooled with a random-effects model.

RESULTS

Of 227 references identified, data were collected from 26 studies and a total of 5,099 adult patients. The pooled prevalence any type of functional bowel disorders in patients who present diagnostic criteria of microscopic colitis was 39.1% (95% CI: 22.8-56.6%; I² : 97%) and was higher for lymphocytic colitis than for collagenous colitis (40.7% vs. 28.4%, respectively; P = 0.58). The prevalence of microscopic colitis in functional bowel disorders patients was 7% (95% CI: 3.6-11.4%), reaching 9.8% (95% CI: 4.4-17.1%; I² : 95%) in patients exhibiting diarrhoea-dominant IBS, nonsignificantly higher than microscopic colitis rates among patients with constipation-dominant IBS (1.3%) or mixed-dominant IBS (1.9%).

CONCLUSIONS

There is a significant overlap of symptoms between microscopic colitis and functional bowel disorders, especially in diarrhoeal subtypes. The high proportion of microscopic colitis among diarrhoea-dominant functional syndromes should serve as a call for more active diagnosis in selected patients.

Inverse Association Between Helicobacter pylori Gastritis and Microscopic Colitis

BACKGROUND

Inflammatory bowel disease is known to be inversely associated with Helicobacter pylori infection of the upper gastrointestinal tract. We hypothesized that a similar inverse association also applied to microscopic colitis.

METHODS

The associations between microscopic colitis and presence of H. pylori-positive chronic active gastritis (CAG), H. pylori-negative CAG, intestinal metaplasia, or gastric atrophy were expressed as odds ratios with their 95% confidence intervals. Multivariate logistic regression analyses were used to adjust these associations for sex, age, percentage residents per ZIP code with white, black, Hispanic, or Asian ethnicity, percentage with college education, average housing values, annual income, and population size of individual ZIP codes.

RESULTS

H. pylori-positive CAG was less common among patients with than without microscopic colitis (odds ratio = 0.61; 95% confidence interval, 0.52-0.70). Intestinal metaplasia also occurred less frequently among patients with than without microscopic colitis (0.75, 0.65-0.86). These inverse associations remained unaffected by adjustments for parameters of ethnicity and socioeconomic status. In contradistinction with H. pylori-positive CAG, H. pylori-negative CAG was more common in patients with than without microscopic colitis (1.54, 1.17-1.97).

CONCLUSIONS

H. pylori infection and microscopic colitis are inversely associated. This observation is consistent with similar inverse associations found between H. pylori and inflammatory bowel disease. These relationships may provide clues about the yet unknown etiology of microscopic colitis.

Microscopic colitis: clinical and pathologic perspectives

Microscopic colitis is a chronic inflammatory bowel disease characterized by chronic nonbloody diarrhea and specific histopathology features. Active disease, defined as 3 or more stools or 1 or more watery stools per day, significantly reduces quality of life. Epidemiologic studies have found the incidence and prevalence of microscopic colitis to be comparable with those of Crohn's disease and ulcerative colitis. Nevertheless, microscopic colitis is still under-recognized in clinical practice-most health care workers know little about its etiology and pathophysiology. Furthermore, there are many challenges to the diagnosis and treatment of patients. We review the epidemiologic and clinical features of this disorder and discuss its pathogenesis. We also outline the criteria for histopathologic evaluation of microscopic colitis, recently published by the European Consensus on Inflammatory Bowel Disease, and discuss a treatment algorithm created by the European Microscopic Colitis Group. Treatment options for patients with budesonide-refractory disease are discussed.

Histology of microscopic colitis-review with a practical approach for pathologists

Microscopic colitis has emerged as a major cause of chronic watery non-bloody diarrhoea, particularly in elderly females. The term is used as an umbrella term to categorize a subgroup of colitides with distinct clinicopathological phenotypes and no significant endoscopic abnormalities. Lymphocytic colitis is defined by an increased number of surface intraepithelial lymphocytes, and collagenous colitis by a thickened collagen band underneath the surface epithelium. There is increased inflammation in the lamina propria, but only little or no crypt architectural distortion. Incomplete and variant forms showing less characteristic features have been reported under different names. The differential diagnosis mainly includes resolving infectious colitis and changes related to the intake of drugs such as non-steroidal anti-inflammatory drugs. Substantial clinical and histological overlap between lymphocytic and collagenous colitis has been described, raising the suspicion that the conditions are two histological manifestations of the same entity, possibly representing different manifestations during the disease course or different stages of disease development. In this review, we provide a practical approach for pathologists, with a focus on diagnostic criteria and differential diagnosis, and discuss recent insights into the pathogenesis of disease and the relationship with classic chronic inflammatory bowel disease, i.e. Crohn's disease and ulcerative colitis.

Long-term prognosis of clinical symptoms and health-related quality of life in microscopic colitis: a case-control study

BACKGROUND

Microscopic colitis, comprising collagenous colitis (CC) and lymphocytic colitis (LC), is a common cause of chronic diarrhoea. The long-term prognosis is not well described.

AIM

To study outcome of symptoms and health-related quality of life (HRQoL).

METHODS

A case-control study using a postal questionnaire with three population-based controls per patient matched for age, sex and municipality. HRQoL was assessed by the Short Health Scale (SHS). Patients in clinical remission, defined as a mean of <3 stools/day, were evaluated separately (CC; n = 72, LC; n = 60).

RESULTS

The study included 212 patients and 627 matched controls. Median disease duration was 5.9 (range 0.5-27) years and 6.4 (0.3-14.8) years for CC and LC respectively. Abdominal pain, fatigue, arthralgia, myalgia, faecal incontinence and nocturnal defecation were significantly more prevalent in CC patients compared with controls. These differences persisted in CC patients in clinical remission with respect to abdominal pain (36% vs. 21%), fatigue (54% vs. 34%), arthralgia (61% vs. 41%) and myalgia (53% vs. 37%). In LC patients, abdominal pain, fatigue, faecal incontinence and nocturnal defecation were more prevalent compared with controls. In LC patients in clinical remission, fatigue was more prevalent compared with controls (54% vs. 37%). These differences were statistically significant (P < 0.05). All four HRQoL dimensions (symptom burden, social function, disease-related worry, general well-being) were impaired in patients with active CC and LC.

CONCLUSIONS

Although considered to be in clinical remission, patients with microscopic colitis suffer from persisting symptoms such as abdominal pain, fatigue, arthralgia or myalgia several years after diagnosis.

Evaluation and treatment of colonic symptoms

Important considerations for constipation include: 1. Initial evaluation should evaluate for fecal incontinence, fecal impaction, medication side effects, concerning symptoms, underlying medical or metabolic issues and irritable bowel syndrome. 2. History and examination should be used to determine if a defecatory disorder is most likely. a. If defecatory disorder is likely, testing with balloon expulsion or anal manometry can be considered and, if confirmed, treatment with biofeedback (if testing not available, it is reasonable to trial fiber and laxatives because many patients have a mixed disorder). b. If it is unlikely, proceed with trial of fiber and/or osmotic laxatives. 3. If continued symptoms, consider trial of newer agent (lubiprostone or linaclotide). 4. If ineffective, consider testing for colon transit time and referral to gastroenterology.

Clinical features and treatment responses in pediatric lymphocytic and collagenous colitis

OBJECTIVE

Microscopic colitis (MC) is prevalent in adults investigated for chronic watery diarrhea, yet characterization of pediatric MC is limited.

METHODS

Our pathology database was searched from 1995 to 2011 for pediatric cases of lymphocytic colitis (LC) or collagenous colitis (CC). Those with diarrhea persisting for >2 weeks and visually normal colonoscopy were accepted as cases. Demographics, laboratory results, medication use within 3 months of presentation, medical and family history of autoimmune disease, and response to treatment were abstracted.

RESULTS

A total of 27 cases were histologically consistent with MC on biopsy; 5 with concomitant enteric infection or isolated abdominal pain were excluded. Twenty-two cases of MC (female patients, 59%; median age at diagnosis, 15.3 years) were included (19 LC and 3 CC). Two had type 1 diabetes mellitus, 2 were anti-nuclear antibody positive, and 2 had common variable immunodeficiency. Of 20 patients who underwent an esophagogastroduodenoscopy, 1 had collagenous sprue and 4 had celiac disease. One presented after the clearance of recurrent Clostridium difficile infection. Previous drug exposures included nonsteroidal anti-inflammatory drugs (n = 7), proton pump inhibitors (n = 6), and selective serotonin reuptake inhibitors (n = 3). Common symptoms in addition to diarrhea included abdominal pain (77.3%) and weight loss (27.3%). Of 17 patients with follow-up, all of the 8 treated with steroids had some response: 57.1% (4/7) responded to mesalamine and 42.9% (3/7) responded to bismuth subsalicylate.

CONCLUSIONS

In this cohort of pediatric patients, LC was much more common than CC. As described in adults, we observed associations with celiac disease, type 1 diabetes mellitus, and medications; we additionally saw an association with immunodeficiency. Our patients showed greater response to steroids than mesalamine or bismuth.

Immunohistochemical characterization of lymphocytes in microscopic colitis

BACKGROUND AND AIMS

Microscopic colitis (MC), encompassing the subgroups collagenous colitis (CC) and lymphocytic colitis (LC), is characterized by macroscopically normal or near-normal colonic mucosa, and an increased number of intraepithelial lymphocytes (IELs) and mononuclear cell infiltration in the underlying lamina propria (LP), in addition to an increased collagen layer in CC. This study aimed to characterize the inflammatory cells involved in mucosal inflammation, using immunohistochemistry.

METHODS

Paraffin-embedded biopsies from 23 untreated patients with MC (CC=13, LC=10) and 17 controls were stained with antibodies against CD3, CD4, CD8, CD20, CD30, Foxp3, CD45RO and Ki67. Computerized image analysis was used to calculate areas of stained lymphocytes in the surface and crypt epithelia as well as in the LP.

RESULTS

In CC and LC, an increase of predominantly CD8(+) lymphocytes was seen in both the epithelium and the lamina propria, whereas a decreased amount of CD4(+) lymphocytes was found in the lamina propria. CD45RO(+) and Foxp3(+) cells were more abundant in all areas in both patient groups compared to controls, as were CD20(+) areas, although more scarce. Ki67(+) areas were only more abundant in the epithelium, whereas CD30(+) areas were more abundant in the lamina propria of both patient groups compared to controls.

CONCLUSIONS

This study confirms an increased amount of CD8(+) lymphocytes in the epithelium. Lymphocytic proliferation and activation markers were more abundant, whereas a decreased amount of CD4(+) lymphocytes was seen in the LP. Further studies are needed to reveal the underlying mechanism(s).

Lymphocytic and collagenous colitis: epidemiologic differences and similarities

BACKGROUND

It is unknown whether the subtypes of microscopic colitis (MC) represent distinct nosologic entities or related presentations of the same disease. Our aim was to search for epidemiologic differences among its various histopathologic subtypes.

METHODS

In a computerized database of 789,568 colon pathology reports, we compared the characteristics of 8,745 MC patients with those of the remaining population.

RESULTS

MC was diagnosed as three distinct histopathologic subtypes: lymphocytic colitis (LC) in 51 %, collagenous colitis (CC) in 43 %, and incomplete colitis (IC) in 6 % of patients. Only 0.65 % was simultaneously diagnosed with more than one subtype of MC. The prevalence of all three subtypes showed an age-dependent rise, with the average age (SD) being 63.3 (14.3) years in LC, 66.4 (12.1) years in CC, and 67.3 (12.7) years in IC (p < 0.0001). There was a striking female predominance in all three subtypes, the female fraction being 72 % in LC, 82 % in CC, and 79 % in IC (p < 0.0001). All three subtypes showed similar geographic distributions among different US states. They were similarly associated with diarrhea and weight loss, the odds ratios for all MC being 45.92 (43.35-48.63) and 5.12 (4.68-5.60), respectively, compared to control patients without MC. All three subtypes also harbored significantly less colonic adenomas, the overall odds ratio being 0.11 (0.10-0.12).

CONCLUSION

MC comes in three distinct histopathologic entities, which show striking similarities of their general epidemiologic features. The slight differences in their demographic characteristics could point at varying sets of environmental influences that affect the occurrence of subtypes.

Microscopic colitis in children with chronic diarrhea

OBJECTIVE

The aim of the present study was to study microscopic colitis (MC) in children with special reference to its role in chronic diarrhea and changes in mucosal biopsies.

METHODS

A total of 100 consecutive children ages 3 to 12 years, with nonbloody diarrhea (passage of ≥3 loose stools per day) of >12 weeks' duration were screened and 26 were enrolled in the study in which no specific etiology could be found and colonoscopy did not reveal any mucosal abnormality. Colonic biopsies were evaluated for the presence of lymphocytic colitis or collagenous colitis and those with the characteristic changes were defined to have MC (group A). Colonic biopsies from patients with MC were compared with biopsies from patients with chronic diarrhea but no evidence of MC (group B). One hundred children ages 3 to 12 years with bleeding per rectum were screened and colonic biopsies from 45 patients (group C) who had colonic mucosal changes but no vascular or polyp lesion were compared with patients with MC.

RESULTS

Of the 26 patients with chronic diarrhea, MC was found in 5 (3 lymphocytic colitis and 2 collagenous colitis). Significantly higher polymorphonuclear infiltration was seen in group A as compared with group B (13.8 [5.4-20.6] vs 7.2 [0-19.6]; P = 0.03) or group C (13.8 [5.4-20.6] vs 4 [0-13.4]; P = 0.007). Intraepithelial lymphocytes (12 [4-32] vs 4 [0-24]; P = 0.008) and basement membrane thickening (3.5 [2.9-10.6] vs 2.5 [1.6-5.86]; P = 0.008) were also significantly higher in group A as compared with group C.

CONCLUSIONS

MC was found to be present in children with nonbloody chronic diarrhea in children. Further multicentric studies may provide adequate data on its prevalence.

Idiopathic microscopic colitis of rhesus macaques: quantitative assessment of colonic mucosa

Idiopathic chronic diarrhea (ICD) is a common cause of morbidity and mortality among juvenile rhesus macaques. While lesions may be absent at colonoscopy, the histopathologic evaluation of the biopsy specimens is consistent with human macroscopic colitis (MC). In this study, we developed an isotropic uniform random sampling method to evaluate macroscopic and microscopic changes and applied it on proximal ascending colon in monkeys. Colonic tissue and peripheral blood specimens were collected from six MC and six control juvenile macaques at necropsy. Uniform random samples were collected from the colon using punch biopsy tools. The volume of epithelium and lamina propria were estimated in thick (25 µm) sections using point probes and normalized to the area of muscularis mucosae. Our data suggests a significant increase of the Vs of the lamina propria (1.9-fold, P = 0.02) and epithelium (1.4-fold, P = 0.05) in subjects with MC. The average colonic surface mucosa area in the MC monkeys increased 1.4-fold over the controls (P = 0.02). The volume of the proximal colon in animals with MC showed a 2.4-fold increase over the non-diarrhea control monkeys (P = 0.0001). Cytokine, chemokine, and growth factor levels in peripheral blood were found to be correlated with the volume estimate of the lamina propria and epithelium. We found that ICD in macaques has features which simulates human MC and can be used as a spontaneous animal model for human MC. Furthermore, this developed sampling method can be used for unbiased preclinical evaluation of therapeutics in this animal model.

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.

Chromogranin A cell density as a diagnostic marker for lymphocytic colitis

BACKGROUND

Lymphocytic colitis (LC) can be mistakenly diagnosed as irritable bowel syndrome (IBS). In a previous study on IBS, some patients showed extremely high colonic chromogranin A cell density. Further examination of these patients showed that they suffered from LC.

AIMS

To investigate whether chromogranin A cell density is increased in LC patients and to examine the possibility of using this increase as a marker for the diagnosis of LC.

METHODS

Fifty-seven patients diagnosed with LC and 54 controls were included in the study. Biopsies from the right and left colon were obtained from both patients and controls, which were immunostained using the Avidin-biotin-complex method for chromogranin A, and cell density was quantified.

RESULTS

In both the right and left colon of patients with LC, the density of chromogranin A was significantly higher than in controls. This increase in chromogranin A cells occurs whether the number of these cells is expressed as number/mm(2) epithelium or as number/field. Chromogranin A cell density for the right and left colon expressed as number of cells/mm(2) epithelium or as cell number/field showed a high sensitivity and specificity as a diagnostic marker for LC.

CONCLUSIONS

Chromogranin A is a common marker for endocrine cells, and the present finding suggests that colonic hormones are involved in the pathophysiology of LC. The chromogranin cell density seems to be a good diagnostic marker with high sensitivity and specificity in both the right and left colon, thus sigmoidoscopy can be used in the diagnosis of LC using with this marker.

Geographic distributions of microscopic colitis and inflammatory bowel disease in the United States

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are characterized by similar geographic distributions. We used a large database of pathology reports to analyze the geographic distribution of microscopic colitis (MC) and compare it with those of UC and CD.

METHODS

A population of 671,176 individual patients with colonic biopsies was studied stratified by gender and state of residence. The occurrence of each diagnosis MC, UC, or CD, was expressed as proportional rate per 1000 colonoscopies with biopsies from each individual state.

RESULTS

UC and CD tended to be common in states in the Northeast or North Central regions of the U.S. and relatively rare among several southern states. MC appeared to follow a somewhat inverse pattern, as it was most common among some states from the Southwest (Colorado, New Mexico, Arizona, Nevada) and other states of southern latitude, such as Florida, Georgia, California, but relatively uncommon among states in the Northeast. The geographic distributions of UC and CD were significantly correlated with each other (R = 0.60 and P = 0.0004). No significant correlation was observed between MC and UC or CD.

CONCLUSIONS

The differences in epidemiologic behavior point at a dissimilar set of risk factors that shape the occurrence of MC as opposed to UC or CD.

Microscopic colitis

Microscopic colitis may be defined as a clinical syndrome, of unknown etiology, consisting of chronic watery diarrhea, with no alterations in the large bowel at the endoscopic and radiologic evaluation. Therefore, a definitive diagnosis is only possible by histological analysis. The epidemiological impact of this disease has become increasingly clear in the last years, with most data coming from Western countries. Microscopic colitis includes two histological subtypes [collagenous colitis (CC) and lymphocytic colitis (LC)] with no differences in clinical presentation and management. Collagenous colitis is characterized by a thickening of the subepithelial collagen layer that is absent in LC. The main feature of LC is an increase of the density of intra-epithelial lymphocytes in the surface epithelium. A number of pathogenetic theories have been proposed over the years, involving the role of luminal agents, autoimmunity, eosinophils, genetics (human leukocyte antigen), biliary acids, infections, alterations of pericryptal fibroblasts, and drug intake; drugs like ticlopidine, carbamazepine or ranitidine are especially associated with the development of LC, while CC is more frequently linked to cimetidine, non-steroidal antiinflammatory drugs and lansoprazole. Microscopic colitis typically presents as chronic or intermittent watery diarrhea, that may be accompanied by symptoms such as abdominal pain, weight loss and incontinence. Recent evidence has added new pharmacological options for the treatment of microscopic colitis: the role of steroidal therapy, especially oral budesonide, has gained relevance, as well as immunosuppressive agents such as azathioprine and 6-mercaptopurine. The use of anti-tumor necrosis factor-α agents, infliximab and adalimumab, constitutes a new, interesting tool for the treatment of microscopic colitis, but larger, adequately designed studies are needed to confirm existing data.

High densities of serotonin and peptide YY cells in the colon of patients with lymphocytic colitis

AIM: To investigate colonic endocrine cells in lymphocytic colitis (LC) patients.

METHODS: Fifty-seven patients with LC were included. These patients were 41 females and 16 males, with an average age of 49 years (range 19-84 years). Twenty-seven subjects that underwent colonoscopy with biopsies were used as controls. These subjects underwent colonoscopy because of gastrointestinal bleeding or health worries, where the source of bleeding was identified as haemorrhoids or angiodysplasia. They were 19 females and 8 males with an average age of 49 years (range 18-67 years). Biopsies from the right and left colon were obtained from both patients and controls during colonoscopy. Biopsies were fixed in 4% buffered paraformaldehyde, embedded in paraffin and cut into 5 μm-thick sections. The sections immunostained by the avidin-biotin-complex method for serotonin, peptide YY (PYY), pancreatic polypeptide (PP) enteroglucagon and somatostatin cells. The cell densities were quantified by computerised image analysis using Olympus software.

RESULTS: The colon of both the patient and the control subjects were macroscopically normal. Histopathological examination of colon biopsies from controls revealed normal histology. All patients fulfilled the diagnosis criteria required for of LC: an increase in intraepithelial lymphocytes (> 20 lymphocytes/100 epithelial cells) and surface epithelial damage with increased lamina propria plasma cells and absent or minimal crypt architectural distribution. In the colon of both patients and control subjects, serotonin-, PYY-, PP-, enteroglucagon- and somatostatin-immunoreactive cells were primarily located in the upper part of the crypts of Lieberkühn. These cells were basket- or flask-shaped. There was no statistically significant difference between the right and left colon in controls with regards to the densities of serotonin- and PYY-immunoreactive cells (P = 0.9 and 0.1, respectively). Serotonin cell density in the right colon in controls was 28.9 ± 1.8 and in LC patients 41.6 ± 2.6 (P = 0.008). In the left colon, the corresponding figures were 28.5 ± 1.9 and 42.4 ± 2.9, respectively (P = 0.009). PYY cell density in the right colon of the controls was 10.1 ± 1 and of LC patients 41 ± 4 (P = 0.00006). In the left colon, PYY cell density in controls was 6.6 ± 1.2 and in LC patients 53.3 ± 4.6 (P = 0.00007).

CONCLUSION: The change in serotonin cells could be caused by an interaction between immune cells and serotonin cells, and that of PYY density might be secondary.

Colorectal normal histology and histopathologic findings in patients with chronic diarrhea

Collagenous and lymphocytic colitis are common causes of chronic watery diarrhea that are characterized by distinct histopathologic abnormalities without endoscopically visible lesions and are summarized as microscopic colitis. Several variants of microscopic colitis have been described, although their clinical significance still has to be defined. Preserved mucosal architecture is a histologic hallmark of microscopic colitis and distinguishes the disease from inflammatory bowel disease (IBD). In addition to architectural abnormalities, the diagnosis of IBD rests on characteristic inflammatory changes. Differential diagnosis of IBD mainly includes prolonged infection and diverticular disease-associated colitis, also known as segmental colitis associated with diverticulosis.

Systematic review: are lymphocytic colitis and collagenous colitis two subtypes of the same disease - microscopic colitis?

BACKGROUND

Despite similar clinical symptoms, collagenous colitis (CC) and lymphocytic colitis (LC) are considered two distinct disease entities.

AIM

To compare pathoanatomical findings, clinical presentations, risk factors, course of diseases and response to treatment in CC and LC to establish whether they could be subtypes of the same disease, microscopic colitis (MC).

METHODS

The MEDLINE was searched for CC, LC and MC, and clinical studies of >20 patients were included. Pooled results with 95% confidence intervals were calculated based on the number of patients.

RESULTS

An abnormal number of intraepithelial lymphocytes are found in 45% (40-50%) with CC, and an abnormal subepithelial collagen band in 16% (13-20%) with LC suggesting a histological overlap. The incidence of CC and LC has increased in parallel. Mean age (CC 63 years; LC 60 years) and clinical presentation are indistinguishable, and females are predominant in CC (77%; 75-79%) as well as LC (68%; 66-70%). Risk factors such as nonsteroid anti-inflammatory drugs consumption CC 39% (36-42%); LC 32% (29-35%) are similar and prevalence of concomitant autoimmune diseases such as coeliac disease (CC 5%; CI: 4-6% and LC 7%; CI: 6-9%) do not differ. Bile acid diarrhoea is highly prevalent in CC (41%; 37-45%) and LC (29%; 24-34%). The effect of budesonide is identical.

CONCLUSIONS

CC and LC could be considered histological subtypes of the same disease, MC. To facilitate recruitment to clinical trials, all MC patients could be included in future trials and stratified for subtypes.

Lymphocytic and collagenous colitis: an overview of so-called microscopic colitis

The entity of 'microscopic colitis' is being diagnosed with increasing frequency and is a well-established clinicopathological diagnosis that is underpinned by a triad of watery diarrhea, normal results on endoscopy and characteristic microscopic findings. Careful histopathological evaluation and awareness of its numerous associations (especially with drugs and celiac disease) and mimics will lead to the correct diagnosis of microscopic colitis. The etiology of microscopic colitis remains enigmatic and is multifactorial with different elements being more influential in different individuals. Treatment includes antidiarrheal agents and anti-inflammatory drugs (including steroids). The purpose of this article is to provide some clarity on nomenclature, discuss the multitude of conditions that can occur synchronously or metachronously with microscopic colitis and their role in the etiopathogenesis of this condition, provide a detailed review of the pathological aspects of the disease and to briefly discuss treatment trends.

Microscopic colitis: clinical findings, topography and persistence of histopathological subgroups

BACKGROUND

Uncertainty remains on topography and persistence of histological subgroups of microscopic colitis (MC).

AIM

To assess longitudinal clinical, endoscopic, histological, and therapeutic description of MC subgroups including patients with incomplete findings of MC (MCi).

METHODS

Retrospective review of a consecutive cohort with MC and histological reassessment of MCi.

RESULTS

Clinical characteristics of 168 patients with lymphocytic colitis (LC), 270 with collagenous colitis (CC) and 101 with MCi were similar. At colonoscopy 95% (95% CI: 91-98%) of CC and 98% (93-100%) of LC cases had diagnostic histopathology of MC in both left and right colon. Eight and three patients had characteristics of MC only in the left and right colon, respectively. Histology findings resembling coexistence of the other MC subtype was present in 48% (40-55%) with CC and 24% (18-31%) with LC. A first diagnosis of MC was made in 49 (30%) of 164 patients only at repeat endoscopy. Another 34 of 115 (30%) with MC in the first endoscopy did not fulfil the MC criteria at repeat endoscopy. Only seven cases had a primary endoscopy without histopathological abnormalities. Fifteen percentage of MCi were reclassified as MC. Ileal inflammation was present in 33 of 81 patients. Budesonide was efficacious in all MC subgroups irrespective of bile acid malabsorption.

CONCLUSIONS

Clinical characteristics of microscopic colitis subgroups are indistinguishable. Biopsies from the left colon suffice to exclude microscopic colitis, and the histological diagnosis of microscopic colitis is inconsistent over time. Ileal inflammation is common. The term microscopic colitis should perhaps be considered one clinical entity and include lymphocytic colitis, collagenous colitis, and incomplete findings of microscopic colitis.