Microscopic colitis: an update

Microscopic Colitis in a Young Male: Unveiling the Rarity

In recent decades, microscopic colitis (MC) has become increasingly recognized as a common contributor to diarrhea and lower gastrointestinal symptoms, particularly among the older demographic. The condition is distinguished by persistent diarrhea with loose watery stools, and endoscopic examination is typically normal with characteristic histopathologic findings. MC is rarely seen under 30 years of age and is less common in males. Our case highlights an exceedingly uncommon clinical setting as it involves a young male who was diagnosed with collagenous colitis. The diagnosis of MC can easily be missed by physicians during initial evaluation. Specifically in irritable bowel syndrome patients with diarrhea predominant symptoms, a colonoscopy should be performed and biopsies should be taken from the entire colon to rule out MC.

Atypical Presentations of Collagenous Gastritis Mimicking Celiac Sprue

Collagenous gastritis has been reported as a rare cause of nausea, diarrhea, weight changes, and early satiety in female patients. Here, we describe two women aged 43 and 71 years who presented with similar symptoms. Gastric biopsies from both individuals showed thickened, irregular subepithelial collagen bands (>10 μm). The pathogenesis of collagenous gastritis is poorly understood, but it may be the presenting symptom for many underlying autoimmune conditions. In particular, there is a well-established connection between collagenous disorders of the gastrointestinal tract and celiac sprue, Sjögren syndrome, and lymphocytic colitis; however, none of these conditions had been diagnosed in our patients. The older woman had incidentally discovered hypogammaglobinemia and IgA deficiency, whereas the younger woman suffered from fibromyalgia. Although a gluten-free diet and budesonide have been effective in some cases, there is no standardized therapy for collagenous gastritis. Our patients trialed diet modification and have required no additional medical interventions.

Collagenous Colitis Is Associated With HLA Signature and Shares Genetic Risks With Other Immune-Mediated Diseases

BACKGROUND & AIMS

Collagenous colitis (CC) is an inflammatory bowel disorder with unknown etiopathogenesis involving HLA-related immune-mediated responses and environmental and genetic risk factors. We carried out an array-based genetic association study in a cohort of patients with CC and investigated the common genetic basis between CC and Crohn's disease (CD), ulcerative colitis (UC), and celiac disease.

METHODS

DNA from 804 CC formalin-fixed, paraffin-embedded tissue samples was genotyped with Illumina Immunochip. Matching genotype data on control samples and CD, UC, and celiac disease cases were provided by the respective consortia. A discovery association study followed by meta-analysis with an independent cohort, polygenic risk score calculation, and cross-phenotype analyses were performed. Enrichment of regulatory expression quantitative trait loci among the CC variants was assessed in hemopoietic and intestinal cells.

RESULTS

Three HLA alleles (HLA-B∗08:01, HLA-DRB1∗03:01, and HLA-DQB1∗02:01), related to the ancestral haplotype 8.1, were significantly associated with increased CC risk. We also identified an independent protective effect of HLA-DRB1∗04:01 on CC risk. Polygenic risk score quantifying the risk across multiple susceptibility loci was strongly associated with CC risk. An enrichment of expression quantitative trait loci was detected among the CC-susceptibility variants in various cell types. The cross-phenotype analysis identified a complex pattern of polygenic pleiotropy between CC and other immune-mediated diseases.

CONCLUSIONS

In this largest genetic study of CC to date with histologically confirmed diagnosis, we strongly implicated the HLA locus and proposed potential non-HLA mechanisms in disease pathogenesis. We also detected a shared genetic risk between CC, celiac disease, CD, and UC, which supports clinical observations of comorbidity.

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

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

A case of spontaneous colonic perforation in collagenous colitis

BACKGROUND

Collagenous colitis (CC) is a clinicopathologic syndrome characterized by chronic watery diarrhea and distinctive histopathologic features. Spontaneous perforation of CC is extremely rare, because CC is usually managed medically, and the need for surgical intervention is rare. We report a surgical case of spontaneous colonic perforation of CC with acute abdomen disease.

CASE PRESENTATION

A 77-year-old man was admitted to our hospital for abdominal pain and watery diarrhea. Computed tomography (CT) showed a thickened bowel wall with edema involving free air around the splenic flexure of the colon. Therefore, we performed emergency surgery with a diagnosis of colonic perforation. Intraoperative findings revealed colonic necrosis at the splenic flexure, so we performed a left hemicolectomy. Histopathological examination revealed typical findings of CC, a thick subepithelial collagenous band and deep ulcers with perforation. The postoperative course was uneventful, and the patient was discharged on the 28th postoperative day. After changing the proton pump inhibitor (PPI) from lansoprazole (LPZ) to rabeprazole (RPZ), he has not complained of diarrhea symptoms.

CONCLUSIONS

Although spontaneous perforation is a rare complication of CC, it is possible to be diagnosed by symptom of acute abdomen disease. This is the seventh case of spontaneous colonic perforation of CC worldwide.

Microscopic Colitis After Fecal Microbiota Transplant

Microscopic colitis (MC) is an inflammatory condition of the large bowel that is associated with chronic, nonbloody diarrhea. Colonoscopy usually demonstrates normal mucosa, while tissue biopsy reveals intraepithelial lymphocytes or a subepithelial collagen band. Although no specific antibody has been discovered, MC is associated with several autoimmune disorders such as celiac disease, Hashimoto’s thyroiditis, and rheumatoid arthritis. There are only a small number of case reports documenting possible hereditary MC cases, but up to 12% of patients with MC have a family history of inflammatory bowel disease. Other associations include proton pump inhibitor use, cigarette smoking, HLA-DQ2/86, and possibly some gastrointestinal infections.

Microscopic colitis: A literature review

Microscopic colitis (MC) refers to chronic inflammation of the colon which is characterized by histologic changes at the level of a radiologically and endoscopically normal mucosa. It is a common cause of chronic non-bloody diarrhea that occurs primarily in older individuals; however, there are few studies in the literature with strong scientific evidence compared to other inflammatory bowel diseases (IBD), which limits the knowledge of physicians and pathologists. This article aims to review the information on MC, describing diagnostic methods and drugs available for treatment. We conducted a search of the Pubmed database and CAPES Portal using the keywords "microscopic colitis", "collagenous colitis", "lymphocytic colitis", and "review" for selection of articles published between 1996 and 2015 related to the topic. Based on the studies discussed in this review, we conclude that MC is a relatively new gastrointestinal disorder, most studies are incipient particularly with respect to pathophysiology and immunology, and budesonide is the best documented short-term treatment. However, further studies are needed to elucidate the best strategy for treatment in the long term.

Spontaneous colonic perforation: a rare complication of collagenous colitis

Collagenous colitis is a clinicopathologic syndrome characterized by chronic watery diarrhea and unique histopathologic features. Spontaneous colonic perforation in the setting of collagenous colitis is a highly unusual complication, with only three cases reported in the literature to date. We present a fourth case and propose a potential pathologic mechanism for acute colonic perforation in this patient population.

Association of lymphocytic colitis and lactase deficiency in pediatric population

Characterized by colonic mucosa intraepithelial lymphocytosis, lymphocytic colitis is primarily an entity presented in the middle-aged to elderly patient population. Very few large series of lymphocytic colitis of childhood occurrence are available in the medical literature. Ten cases each of lymphocytic colitis and of colonic lymphocytosis of other diagnosis, all with duodenal disaccharidases analysis data, were collected from the files of our institution. The electronic medical records were reviewed and multiple variables were analyzed. The ten patients with lymphocytic colitis presented with diarrhea. Of these, three had abdominal pain. The age range was 2-18 years. Nearly all patients were Caucasian (90%) and 70% were female. Endoscopically, most had normal appearing colonic mucosa. Significant past medical history, family medical history and associated comorbidities included celiac disease, Down syndrome, juvenile arthritis and other autoimmune diseases. Interestingly, the most revealing observation was that the majority of cases (80%) were associated with lactase deficiency and, for the most part, gastrointestinal symptoms improved simply by treatment with Lactaid or avoidance of dairy products. This association is statistically significant. Our clinicopathological study indicates that the typical pediatric patient is a female Caucasian. A large of portion of the patients had associated lactase deficiency and improved on Lactaid supplement alone.

Observer variability in the histopathologic diagnosis of microscopic colitis and subgroups

The diagnosis of microscopic colitis (MC) is based on histologic findings and includes collagenous colitis (CC) and lymphocytic colitis (LC). Incomplete MC (MCi) denotes patients with chronic diarrhea and a normal endoscopy and morphological changes that do not completely meet the histologic criteria of LC or CC. The aim of this study was to investigate the intraobserver and interobserver agreement on the MC subtypes of CC, LC, and MCi and the ability to discriminate MCi from normal and inflammatory bowel disease/nonspecific reactive changes. A single hematoxylin and eosin-stained specimen from biopsies of the following 5 groups were randomly selected and blinded: CC, LC, MCi, inflammatory bowel disease, and normal. Three pathologists independently reviewed the specimens. The specimens were relabeled and reinterpreted 4 months later. Intraobserver and interobserver agreement was evaluated by κ statistics. κ values for intraobserver agreement were good for 5 diagnostic groups varying from 0.70 to 0.83 and very good when simplifying to only 3 diagnostic groups varying from 0.88 to 0.96, separating MC/MCi from non-MC. κ values for interobserver agreement varied from 0.60 to 0.75 for 5 diagnostic groups and 0.81 to 0.89 for 3 diagnostic groups. The study shows that the intraobserver and interobserver agreement is high for discriminating between MC/MCi and non-MC, whereas the ability to discriminate MCi from CC and LC is lower. A revision and consensus on the histologic criteria of the MC subtypes seem warranted.

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.

Lymphocytic follicles and aggregates are a determinant of mucosal damage and duration of diarrhea

CONTEXT

Nonspecific changes (nonspecific chronic inflammation) in patients with chronic diarrhea represent the commonest diagnosis in colorectal biopsy interpretation, but these changes are of little clinical significance.

OBJECTIVE

To find, within this group, histologic and immunohistologic diagnostic criteria to predict the duration and resolution of diarrhea.

DESIGN

Detailed clinical features and histologic findings were analyzed in a cohort of 47 patients with chronic diarrhea, with near-normal histology and no clear-cut known etiologic agent. Immunohistochemistry to mast cells (CD117) and Treg cells (FOXP3) was also assessed in 39 patients.

RESULTS

Increased number of lymphoid follicles and aggregates, increased number of mast cells, and paucity of Treg were the statistically significant key findings (P  =  .003, P  =  .008, and P  =  .04, respectively). The duration of diarrhea was correlated with the number of large lymphoid follicles and aggregates (P  =  .001, r  =  .48), number of total lymphoid follicles and aggregates (P  =  .003, r  =  .43), density of lymphoid follicles and aggregates (P  =  .009, r  =  .38), and total lymphoid follicles and aggregates per biopsy (P  =  .004, r  =  .42) and the number of mast cells (P  =  .001, r  =  .52). The number of mast cells and Treg cells showed significant difference between resolved and unresolved cases (P  =  .001 and P  =  .01 respectively).

CONCLUSIONS

Lymphocytic follicles and aggregates colitis, previously regarded as of negligible diagnostic significance, allows the prediction of the behavior of chronic diarrhea in a subset of patients with nonspecific changes on colonic biopsy. The increased number of mast cells and paucity of Treg cells further helps to identify such unresolved cases.

Is microscopic colitis a drug-induced disease?

Microscopic colitis (MC) is diagnosed in up to 13% of patients investigated for chronic diarrhea, particularly in middle-aged and elderly patients. Recent studies have suggested an etiological role for various drugs, including nonsteroidal anti-inflammatory drugs and proton pump inhibitors. To ascertain the potential role for drug exposure in the development of MC, we performed a systematic review based on a MEDLINE search and conducted a meta-analyses on the available data. We also give an overview of the case reports and studies illustrating the role of drugs in inducing MC. A number of hypotheses are formulated with regard to the potential pathophysiological mechanisms in drug-induced MC. However, confirmative evidence is still largely lacking. Considering the high number of drug users and the relatively low incidence of MC, it is more likely that drug-induced cases of MC are the result of an idiosyncratic reaction.

Collagenous colitis-like condition in immunosuppressed infant baboons

BACKGROUND

Collagenous colitis is a chronic inflammatory bowel disease of unknown etiology. It is fairly common in adult humans, but rare in infants, and has been associated with autoimmune disorders.

METHODS

We report four infant baboons (age 7-12 months) that had received a transplant at 3 months of age and subsequent immunosuppressive therapy for periods of 4-10 months. All presented identical symptoms within a period of 4 weeks, including weight loss associated with chronic watery diarrhea that was unresponsive to standard antimicrobial treatment.

RESULTS

Clinical chemistry evaluations were within normal ranges, viral causes were ruled out, and fecal and blood cultures were repeatedly negative. At necropsy, two infant baboons were found to have a form of collagenous colitis. In the remaining two baboons that had identical clinical features, immunosuppressive therapy was discontinued and treatment with budesonide was initiated. Both baboons recovered and remained well on no medication until the end of follow-up (24 months).

CONCLUSIONS

Collagenous colitis has occasionally been reported in patients with organ transplants. It has been reported only once previously in baboons. The four cases reported here strongly suggest that 1) clinical features as well as histopathological findings of collagenous colitis in baboons are very similar to those in human patients; 2) it was associated with the immunocompromised state of the baboons, as two nonimmunosuppressed age-matched baboons in close proximity did not develop the condition; and 3) it may have had an infectious origin, as all four cases developed within a 4-week period of time.

Cardiac arrest due to lymphocytic colitis: a case report

INTRODUCTION

We present a case of cardiac arrest due to hypokalemia caused by lymphocytic colitis.

CASE PRESENTATION

A 69-year-old Caucasian man presented four months prior to a cardiac arrest with watery diarrhea and was diagnosed with lymphocytic colitis. Our patient experienced a witnessed cardiac arrest at his general practitioner's surgery. Two physicians and the emergency medical services resuscitated our patient for one hour and four minutes before arriving at our university hospital. Our patient was defibrillated 16 times due to the recurrence of ventricular tachyarrhythmias. An arterial blood sample revealed a potassium level of 2.0 mmol/L (reference range: 3.5 to 4.6 mmol/L) and pH 6.86 (reference range: pH 7.37 to 7.45). As the potassium level was corrected, the propensity for ventricular tachyarrhythmias ceased. Our patient recovered from his cardiac arrest without any neurological deficit. Further tests and examinations revealed no other reason for the cardiac arrest.

CONCLUSION

Diarrhea can cause life-threatening situations due to the excretion of potassium, ultimately causing cardiac arrest due to hypokalemia. Physicians treating patients with severe diarrhea should consider monitoring their electrolyte levels.

Anti-Yersinia antibodies are not associated with microscopic colitis in an American case-control study

BACKGROUND

Microscopic colitis (MC), which consists of lymphocytic colitis and collagenous colitis, may be triggered by gastrointestinal infections. Studies have suggested a relationship between MC and Yersinia enterocolitica infection. We tested this hypothesis in a case-control study of American patients with MC.

METHODS

Serum was collected from 47 patients with MC and 44 age- and gender-matched healthy controls at a large referral center in the mid-western United States. Anti-IgA and IgG antibodies to Y. enterocolitica were measured using an enzyme-linked immunosorbent assay (ELISA). Fisher's exact test was used to assess statistical significance.

RESULTS

There were no differences between the two groups for seroprevalence of anti-Yersinia IgA (cases 2.1%, controls 2.3%, p = 1.00) or IgG antibodies (cases 4.3%, controls 6.8%, p = 0.67). There was no correlation between antibody titers and duration of MC diagnosis.

CONCLUSION

Our data do not support the role of exposure to Y. enterocolitica in an American group of patients with MC.

Organic colonic lesions in 3,332 patients with suspected irritable bowel syndrome and lacking warning signs, a retrospective case--control study

PURPOSE

The diagnosis of irritable bowel syndrome is symptom based, and colonoscopy is the most direct way to rule out organic colonic diseases. It is controversial on the necessity of colonoscopy for patients with suspected irritable bowel syndrome and lacking alarm features. This study was designed to verify the organic lesions and discuss the value of colonoscopy in this type of patients.

METHODS

Colonoscopy of 3,332 patients with suspected irritable bowel syndrome and lacking warning signs from 2000 to 2009 were reviewed. One thousand five hundred eighty-eight patients under 50 years of age who underwent colonoscopy screening for health care in the same period were used as controls. The prevalence of different colonic organic lesions was compared between two groups.

RESULTS

Organic colonic lesions were found in 30.3% of the patients with suspected irritable bowel syndrome (1,010/3,332) and 39.0% of the controls (619/1,588). Compared with controls, patients with suspected irritable bowel syndrome had higher prevalence of noninflammatory bowel disease and noninfectious colitis and terminal ileitis, however, had lower prevalence of diverticular disease, adenomatous polyps, and non-adenomatous polyps (all P < 0.001).

CONCLUSIONS

The diagnostic sensitivity of symptom criteria on irritable bowel syndrome without colonoscopy is not more than 69.7% in patients with suspected irritable bowel syndrome lacking warning signs. Though the method of colonoscopy is hard to screen tumor in this type of patients, it is beneficial to uncover some other relevant organic lesions such as terminal ileitis. Colonoscopy should not be refused to suspected irritable bowel syndrome patients without warning signs.

The spectrum of drug-related colitides: important entities, though frequently overlooked

BACKGROUND

There is at present a relative lack of knowledge concerning drug-related colitides, although these may be not infrequent entities in clinical practice.

AIMS

To assess the frequency and the clinical-pathological subtypes of drug-related colitides in a gastrointestinal pathology referral centre.

METHODS

All charts of endoscopic biopsy samples referred for colitis in a eight-year period were reviewed. To be classified as drug related colitis, patients' charts should report the use of any drug in a two month period before colonoscopy and no other obvious cases of colitis be present. For analysis, we considered only patients taking one drug in this period.

RESULTS

We found 122 cases of drug-related colitis out of 3877 charts reviewed (3% of the overall colitis group). These cases were represented by microscopic colitis (50%), eosinophil rich infiltrate of the left colon (34%), ischemic colitis (11%), pseudomembranous colitis (3%), apoptotic colopathy (2%). The drugs most frequently associated with these colitides were represented by non-steroidal anti-inflammatory drugs.

CONCLUSION

It is important to raise awareness concerning drug-related colitides, to avoid diagnostic errors and provide a better therapeutic approach to patients with these conditions.

Low bone mass in microscopic colitis

BACKGROUND

Microscopic colitis presents with similar symptoms to classic inflammatory bowel diseases. Osteoporosis is a common complication of Crohn's disease but there are no data concerning bone metabolism in microscopic colitis.

AIMS

The aim of the present study was to evaluate bone density and metabolism in patients with microscopic colitis.

METHODS

Fourteen patients microscopic colitis were included in the study, and 28 healthy persons and 28 age and gender matched Crohn's disease patients were enrolled as controls. Bone mineral density was measured using dual x-ray absorptiometry at the lumbar spine, femoral neck and the radius. Serum bone formation and bone resorption markers (osteocalcin and beta-crosslaps, respectively) were measured using immunoassays.

RESULTS

Low bone mass was measured in 57.14% patients with microscopic colitis. Bone mineral density at the femoral neck in patients suffering from microscopic colitis and Crohn's disease was lower than in healthy controls (0.852 ± 0.165 and 0.807 ± 0.136 vs. 1.056 ± 0.126 g/cm²; p < 0.01). Bone mineral density at the non-dominant radius was decreased in microscopic colitis patients (0.565 ± 0.093 vs. 0.667 ± 0.072 g/cm²; p < 0.05) but unaffected in Crohn's disease patients (0.672 ± 0.056 g/cm²). Mean beta-crosslaps concentration was higher in microscopic colitis and Crohn's disease patients than controls (417.714 ± 250.37 and 466.071 ± 249.96 vs. 264.75 ± 138.65 pg/ml; p < 0.05). A negative correlation between beta-crosslaps concentration and the femoral and radius t-scores was evident in microscopic colitis patients.

CONCLUSIONS

Low bone mass is frequent in microscopic colitis, and alterations to bone metabolism are similar to those present in Crohn's disease. Therefore, microscopic colitis-associated osteopenia could be a significant problem in such patients.

Microscopic colitis as a missed cause of chronic diarrhea

AIM: To determine the prevalence of increased intraepithelial lymphocytes, using immunohistochemistry in patients with normal colonoscopy and near normal biopsy.

METHODS: We retrospectively reviewed all non-malignant colon mucosal biopsies between 2005 and 2007, reported as normal, chronic inflammation or melanosis coli in patients who were undergoing routine colonoscopy. Immunohistochemistry using CD3 was performed on all mucosal biopsies and an intraepithelial lymphocyte count (IEL) was determined. Cases with an IEL count of ≥ 20 IELs per 100 surface epithelial cells were correlated with demographic, clinical and follow-up data. A further subgroup was evaluated for lymphocytic colitis.

RESULTS: Twenty (8.3%) of 241 cases revealed an IEL count ≥ 20. Six (2.5%) patients were identified as having lymphocytic colitis (P < 0.001), of whom, five were missed on initial evaluation (P = 0.01). Four of these five patients were labeled with diarrhea-predominant irritable bowel syndrome (IBS). On follow-up, three of the remaining 20 cases were diagnosed with malignancy (renal cell carcinoma and myelodysplastic syndrome) and one had an unknown primary tumor with multiple liver metastases. Two cases of collagenous colitis with an IEL count < 10 were included in this study. Increased IELs were not confined to patients with diarrhea as a primary presenting symptom, but were also present in patients with abdominal pain (n = 7), constipation (n = 3) and loss of weight (n = 1).

CONCLUSION: Immunohistochemistry using CD3 is of value in identifying and quantifying IELs for the presence of microscopic colitis in patients with diarrhea-predominant IBS.

The collagenous gastroenteritides: similarities and differences

Collagenous gastritis, collagenous sprue, and collagenous colitis share striking histologic similarities and occur together in some patients. They also share some drug and disease associations. Pediatric cases of collagenous gastritis, however, lack most of these associations. The etiologies of the collagenous gastroenteritides are not known, so it is not clear whether they are similar because they share pathogeneses, or because they indicate a common histologic response to varying injuries. The features, disease and drug associations, and the inquiries into the pathogenesis of these disorders are reviewed.

Proton pump inhibitor use is associated with an increased risk for microscopic colitis: a case-control study

BACKGROUND

Microscopic colitis causes chronic watery diarrhoea. Recent studies have suggested an aetiological role for various medications, including proton pump inhibitors, in the pathogenesis of microscopic colitis.

AIM

To determine whether an association exists between microscopic colitis and proton pump inhibitor use in patients with documented microscopic colitis vs. age- and gender-matched controls.

METHODS

In this retrospective case-control study, cases of microscopic colitis from a secondary and tertiary referral medical centre diagnosed in the last 5 years were reviewed. Demographic characteristics, clinical, histological and endoscopic records, as well as exposure to PPIs and NSAIDs were assessed. Controls from the population were matched to cases by gender and by age.

RESULTS

During the investigated period, 136 cases were identified in both hospitals. Of these, 95 cases of microscopic colitis were retrieved for detailed analysis. Exposure to proton pump inhibitors at the time of the histological diagnosis was significantly higher in patients with collagenous colitis than in controls [38% vs. 13%, P < 0.001; adjusted OR of 4.5 (95% CI 2.0-9.5)].

CONCLUSIONS

This observation confirms the presumed association between microscopic colitis and PPI use, and it supports the possible aetiological role of PPI exposure in the development of microscopic colitis.

The yield of colonoscopy in patients with non-constipated irritable bowel syndrome: results from a prospective, controlled US trial

OBJECTIVES

There are limited data on the yield of colonoscopy in patients with irritable bowel syndrome (IBS). This study compared the prevalence of structural colonic lesions in patients with suspected non-constipation-predominant IBS and healthy volunteers. We also determined the yield of rectosigmoid biopsies in patients with suspected IBS.

METHODS

This was a prospective, case-control study conducted at three US sites. Patients with suspected non-constipation-predominant IBS (Rome II) underwent colonoscopy with rectosigmoid biopsies. Healthy persons undergoing colonoscopy for colorectal cancer screening or polyp surveillance comprised the control group. Abnormalities identified at colonoscopy were compared between suspected IBS and control groups.

RESULTS

In all, 466 suspected IBS patients and 451 controls were enrolled. Suspected IBS patients were significantly younger (P<0.0001) and more frequently female (P<0.0001) than controls. The most common lesions in suspected IBS patients were hemorrhoids (18.2%), polyps (14.6%), and diverticulosis (8.8%). Suspected IBS patients had a lower prevalence of adenomas (7.7% vs. 26.1%, P<0.0001) and diverticulosis (8.8% vs. 21.3%, P<0.0001) and higher prevalence of mucosal erythema or ulceration (4.9% vs. 1.8%, P<0.01) compared with controls. Logistic regression found the between-group differences in adenoma prevalence to be robust after correction for demographic factors. The overall prevalence of microscopic colitis in suspected IBS patients was 1.5% (7/466) and 2.3% (4/171) in those > or =45 years of age.

CONCLUSIONS

The prevalence of structural abnormalities of the colon is no higher in suspected non-constipation IBS patients than in healthy controls. Microscopic colitis can be identified in a small proportion of persons with IBS symptoms.