Atypical forms of microscopic colitis: morphological features and review of the literature

Microscopic Colitis: A Review Article

Microscopic colitis (MC) is a chronic inflammatory disease that affects the older population. Its clinical presentation includes a variety of gastrointestinal manifestations. The main symptom is chronic watery, nonbloody diarrhea. The disease has a female predominance. The diagnosis might be challenging since the symptoms are similar to other differential diagnoses, such as celiac disease, irritable bowel syndrome, Crohn's disease, bacterial overgrowth, and infectious colitis. The golden diagnostic tool for diagnosis is performing colonoscopy to obtain the colonic biopsy, which demonstrates the characteristic histological evidence needed for diagnosis. The treatment starts with an accurate diagnosis and trial of any possible offending medications. Alternatively, there are many medications, such as bismuth or budesonide, which are very effective in treating this disease. The primary objective of this detailed review is to enhance knowledge and understanding of this condition among healthcare providers to guide them with detailed information regarding epidemiology, clinical presentation, diagnosis, and appropriate management. In the assessment of individuals presenting with persistent chronic diarrhea, it is essential for healthcare providers to consider MC as a probable differential 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.

Microscopic colitis: lymphocytic colitis, collagenous colitis, and beyond

Microscopic colitis (MC) is a chronic inflammatory disease of colon with clinical presentations of chronic, watery, nonbloody diarrhea, and normal or almost normal endoscopic findings. Confirmation of a diagnosis of MC requires microscopic examination on colon biopsy to identify characteristic morphological features, in which 2 main subtypes of MC, lymphocytic colitis (LC) and collagenous colitis (CC), have been described. Although the pathogenesis of MC is still unclear, studies have revealed associations of MC with many risk factors and other diseases such as celiac disease, inflammatory bowel disease, and medication use. Meanwhile, variants of MC, MC incomplete, or MC-like changes in other conditions are still diagnostic dilemmas for pathologists. The goal of this paper is to systemically introduce the clinicopathologic features of MC and focus on unusual features of MC and its associations with other conditions.

Diagnosis and Management of Microscopic Colitis in Pediatric Patients

Microscopic colitis (MC) is an inflammatory disease of the colon, characterized by chronic watery diarrhea with distinguishing histologic findings despite normal endoscopic appearance of the colonic mucosa. MC is a common cause of diarrhea in older adults, though it has been infrequently reported in children and adolescents. As MC is rare in the pediatric population, and the clinical presentation is non-specific, increased awareness of this disease amongst pediatric clinicians and pathologists is essential for timely diagnosis, which requires performing colonoscopy with biopsy. The etiology of MC is incompletely understood, but current theories in pathogenesis inform management strategies. The goals of management in pediatric MC should be to achieve symptomatic improvement while minimizing adverse effects of treatment. Many patients who achieve clinical response have symptomatic recurrence after discontinuation of initial therapy, and may require maintenance medication therapy to sustain remission. This review aims to summarize the epidemiology and risk factors, clinical features, diagnosis, theories regarding pathogenesis, and suggested management approaches for MC in the pediatric population.

European guidelines on microscopic colitis: United European Gastroenterology and European Microscopic Colitis Group statements and recommendations

INTRODUCTION

Microscopic colitis is a chronic inflammatory bowel disease characterised by normal or almost normal endoscopic appearance of the colon, chronic watery, nonbloody diarrhoea and distinct histological abnormalities, which identify three histological subtypes, the collagenous colitis, the lymphocytic colitis and the incomplete microscopic colitis. With ongoing uncertainties and new developments in the clinical management of microscopic colitis, there is a need for evidence-based guidelines to improve the medical care of patients suffering from this disorder.

METHODS

Guidelines were developed by members from the European Microscopic Colitis Group and United European Gastroenterology in accordance with the Appraisal of Guidelines for Research and Evaluation II instrument. Following a systematic literature review, the Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the certainty of the evidence. Statements and recommendations were developed by working groups consisting of gastroenterologists, pathologists and basic scientists, and voted upon using the Delphi method.

RESULTS

These guidelines provide information on epidemiology and risk factors of microscopic colitis, as well as evidence-based statements and recommendations on diagnostic criteria and treatment options, including oral budesonide, bile acid binders, immunomodulators and biologics. Recommendations on the clinical management of microscopic colitis are provided based on evidence, expert opinion and best clinical practice.

CONCLUSION

These guidelines may support clinicians worldwide to improve the clinical management of patients with microscopic colitis.

Microscopic Colitis Evolved Into Inflammatory Bowel Diseases Is Characterized by Increased Th1/Tc1 Cells in Colonic Mucosal Lamina Propria

BACKGROUND

An association between microscopic colitis (MC), i.e., lymphocytic colitis (LC) and collagenous colitis (CC), and inflammatory bowel diseases (IBD) has been noticed. A subset of MC cases may evolve into IBD, and IBD in remission may present as MC in a histologic pattern. Moreover, MC and IBD may coexist in different regions of the bowel. A link between MC and IBD in their pathogenesis is, therefore, suggested. Abnormal mucosal immunity is likely the key.

METHODS

We reviewed 2324 MC cases in Calgary over 14 years and identified 20 cases evolved into IBD (IBD transformers). 13 of them were further investigated for colonic mucosal lamina propria mononuclear cells (LPMNCs), as opposed to 22 cases whose MC resolved. On their index colonic biopsy immunohistochemistry was performed to detect major T cell subsets characterized by key cytokines and master transcription factors (IFNγ and T-bet for Th1/Tc1, GATA-3 for Th2/Tc2, IL-17 and RORc for Th17/Tc17, FoxP3 for Treg/Tcreg) as well as TNFα⁺ cells (partly representing Th1). LPMNCs positive for each marker were counted (average number per high-power field).

RESULTS

IBD transformers had increased IFNγ⁺, T-bet⁺, TNF-α⁺, and GATA-3⁺ LPMNCs compared to the MC-resolved cases. The LC-to-IBD subgroup had increased IFNγ⁺ and GATA-3⁺ cells compared to the LC-resolved subgroup. The CC-to-IBD subgroup had increased T-bet⁺, TNF-α⁺, and GATA-3⁺ cells compared to the CC-resolved subgroup. Among MC-resolved patients, more TNF-α⁺ and RORc⁺ cells were seen in LC than in CC.

CONCLUSION

Th1/Tc1- and TNFα-producing cells, and likely a subset of Th2/Tc2 cells as well, may be involved in the MC-to-IBD transformation.

Chronic Colitis in Biopsy Samples: Is It Inflammatory Bowel Disease or Something Else?

Chronic colitis, regardless of type, is defined histologically by chronic inflammation, mainly plasmacytosis, in the lamina propria. Specific diagnosis of chronic colitides in biopsies can be challenging for practicing pathologists. This article focuses on discussing specific histologic features in biopsies of the inflammatory bowel diseases (IBDs), including ulcerative colitis, Crohn colitis, and colitis of indeterminate type. It also offers suggestions as to how to separate the IBDs from other chronic colitides, such as lymphocytic colitis, collagenous colitis, diverticular disease-associated colitis, diversion colitis, and chronic colitides that are due to drugs. Normal histology in colon biopsies is also briefly discussed.

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.

Advances for improved diagnosis of microscopic colitis in patients with chronic diarrhoea

Microscopic colitis is a generic term that includes 2 main forms, collagenous colitis and lymphocytic colitis, and describes a form of inflammatory bowel disease with a chronic and relapsing course. The incidence of microscopic colitis is between 2 and 8 times higher in women than in men, although age, more than sex, increases the risk of collagenous colitis (odds ratio [OR] 8.3 for age ≥65 vs. <65 and OR 2.8 for women). The main symptom is chronic non-bloody watery diarrhoea. Other common symptoms include abdominal pain (50%-70%), with the result that many patients with microscopic colitis meet criteria for irritable bowel syndrome. Colonoscopy with multiple colonic biopsies is currently recommended, as histological changes are the main characteristic feature. The colonic mucosa is macroscopically normal, although certain minimal endoscopic abnormalities have been described.

CD3 immunohistochemical staining in diagnosis of lymphocytic colitis

Microscopic colitis (MC) is a common cause of chronic watery diarrhea. Traditionally, MC encompasses the 2 subgroups lymphocytic colitis (LC) and collagenous colitis, but recently, an additional subgroup, MC incomplete, has been introduced. Distinguishing between the subgroups relies exclusively on histopathologic evaluation. In the present study, 4 pathologists evaluated 156 archived biopsies originally diagnosed as LC or LC incomplete (LCi). Each pathologist assigned a diagnosis of LC, LCi, or nonspecific inflammation to all cases at 2 independent assessments. At the first assessment, hematoxylin and eosin (HE) stainings were available. At the second assessment, a supplementary CD3 immunohistochemical staining was also available. The aim was to evaluate whether a supplementary CD3 would increase the diagnostic agreement among pathologists, and whether a CD3 stain would change the diagnosis based on HE staining only. After the complete assessment, the cases were divided into 3 groups, that is, full agreement, partial agreement, and disagreement. The CD3 staining increased the number of cases with full agreement from 60 to 78. One hundred thirty-one cases with agreement or partial diagnostic agreement based on HE + CD3 were compared with the HE diagnoses. In 44 (34%) of 131 cases, CD3 changed the diagnosis. Cases assigned to the LCi category based on HE were often changed by a supplementary CD3. Conclusively, it is recommended to use a CD3 before giving the histopathologic diagnosis of LCi.

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.

VSL#3 induces and maintains short-term clinical response in patients with active microscopic colitis: a two-phase randomised clinical trial

BACKGROUND

The probiotic mixture VSL#3 has proven efficacious in inflammatory bowel diseases and irritable bowel syndrome; however, its efficacy in microscopic colitis (MC) is being investigated.

OBJECTIVE

To evaluate the safety and efficacy of a multistrain probiotic, VSL#3, in inducing clinical remission and achieving clinical response, as compared with mesalamine, in patients with active MC.

METHODS

A randomised, open labelled study comparing the efficacy of 900 billion colony-forming units/day of VSL#3 (group (Gp) A) or 1.6 g of mesalamine/day (Gp B) for 8 weeks in 30 patients with MC was conducted. After a washout period of 2 weeks, Gp B received 8 weeks of VSL#3 and Gp A was off medication for the next 8 weeks. The primary end points were clinical remission and clinical response at 8 weeks.

RESULTS

Of 30 patients, 15 were randomised in each arm. 11 patients in Gp A and 13 patients in Gp B completed 8 weeks of treatment. 5 (46%) of 11 patients in Gp A and 1 (8%) of 13 patients in Gp B attained clinical remission (p=0.022). Clinical response was seen in Gp A, as evidenced by a lower stool weight (377.6±104.5 g) as compared with Gp B (507±168.2 g; p=0.03). VSL#3 was effective in maintaining clinical response up to 10 weeks, even after discontinuation of therapy. Secondary end points like stool parameters, histology and well-being improved in both treatment groups.

CONCLUSIONS

The probiotic VSL#3 was found to offer the benefit of inducing as well as maintaining short-term clinical response in patients with active MC.

TRIAL REGISTRATION NUMBER

The clinical trial is registered with CLINICAL TRIAL REGISTRY INDIA; http://ctri.nic.in, CTRI No. "CTRI/2008/091/000086" (registered on: 23/06/2008).

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.

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.

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.

Evaluation of endoscopist and pathologist factors affecting the incidence of microscopic colitis

BACKGROUND

Microscopic colitis (MC) is an umbrella term for collagenous colitis (CC) and lymphocytic colitis (LC). The incidence of these diseases is increasing for unclear reasons.

OBJECTIVE

To identify factors that may impact diagnosis rates of MC in a North American population.

METHODS

Population-based pathology and endoscopy databases were searched to identify all cases of MC and the number of lower endoscopy (LE) procedures performed over a five-year period (January 2004 to December 2008) in a catchment area of 1.2 million people. Endoscopist characteristics were compared with diagnostic rates.

RESULTS

MC incidence increased from 1.68 per 10,000 in 2004, to 2.68 per 10,000 in 2008, with an average annual increase of 12% per year (95% CI 7% to 16%; P<0.0001). The incidence rate of LC increased but the rate of CC remained stable over the study period. Approximately one-half of the cases were probable and one-half were definite based on pathologists' reports - a proportion that remained stable over time. The number of LEs per population increased by 4.6% annually over the study period (95% CI 2.8% to 6.4%; P<0.0001), and biopsy rates in LE for MC indications (eg, unexplained diarrhea, altered bowel habits) increased over time (3.4% annual increase [95% CI 1.8% to 6.0%]; P<0.001). Endoscopists with an academic practice, gastroenterologists and those with lower annual endoscopy volumes were more likely to make a diagnosis of MC.

CONCLUSION

The incidence of MC is rising due to increased diagnosis of LC, while CC incidence remains stable. Patients with MC symptoms have stable endoscopy rates but are being biopsied more often. Physician training, practice type and endoscopy volume impact the diagnostic rates of MC.

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.

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.

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.

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.

From cytokines to toll-like receptors and beyond - current knowledge and future research needs in irritable bowel syndrome

The irritable bowel syndrome (IBS) is a complex disorder in which psychosocial, cultural and biological factors, interact. Recent knowledge in the pathophysiology of IBS, seem to combine issues such as a low grade inflammation or immune activation and dysbiosis that can trigger or exacerbate IBS. On the other hand, stress mediated through the hypothalamic-pituitary-adrenal axis can produce motility abnormalities that can modify the microbiota as well, with the subsequent immune activation in the mucosa and stimulation of nerve terminals, generating symptoms of IBS. Also, we speculate that, stress, dysbiosis or an underlying genetic predisposition, may increase the epithelial permeability leading to a contact between pathogens-associated molecular patterns and toll-like receptors in the deeper layers of the gut, developing a host immunity response and IBS generation. We believe that the role of toll-like receptors in IBS and elucidating the communication processes between the immune and the nervous system, warrant future research.

Microscopic colitis in children

BACKGROUND

Microscopic colitis typically presents with chronic watery nonbloody diarrhea with normal endoscopy findings but abnormal inflammatory histopathological findings. As it is mainly a condition of the elderly, pediatric data is scarce.

AIMS

To describe and characterize children with microscopic colitis.

METHODS

The pathology database at the University of Alberta Hospital together with the pediatric inflammatory bowel disease database at the Stollery Children's Hospital were both searched from September 1996 to May 2008. Charts of all children under the age of 17 years who fulfilled the diagnostic criteria of microscopic colitis were examined.

RESULTS

Eleven children (four girls, mean age at diagnosis 11.2 years, +/- 4.4 years) fulfilled the inclusion criteria. The patients were followed up for a mean of 24.8 months (standard deviation, SD 15.2 months). Two patients were on proton pump inhibitors, two had stool organisms, and two had immunodeficiency. All patients had normal endoscopy and colonoscopy on visualization. Five patients were diagnosed with lymphocytic colitis and the rest had nonspecific/eosinophilic microscopic colitis. The majority of children responded to mesalazine. One patient with immunodeficiency was difficult to manage.

CONCLUSIONS

Microscopic colitis is rare in children. Microscopic eosinophilic colitis is an underdescribed variant of microscopic colitis. The majority of children with microscopic colitis respond well to aminosalicylic acid (5-ASA) medications. Microscopic colitis associated with immunodeficiency can be very challenging to manage. Large multicenter pediatric trials with long-term follow-up are needed to allow investigators to have a better understanding of this rare condition in children.

An association between microscopic colitis and celiac disease

BACKGROUND & AIMS

Microscopic colitis has been associated with celiac disease. We aimed to determine the extent and significance of this relationship.

METHODS

A prospectively maintained database of celiac disease patients, seen between 1981 and 2006, was analyzed. Standardized morbidity ratios (SMR) were calculated using a general population study of microscopic colitis as the reference group. Statistical analysis was conducted using the Student t test, Pearson chi(2) test, or Fisher exact test.

RESULTS

Microscopic colitis was found in 44 of 1009 patients (4.3%); this represented a 70-fold increased risk for individuals with celiac disease to have microscopic colitis, compared with the general population (SMR, 72.39; 95% confidence interval [CI], 52.52-95.36). The celiac disease patients with microscopic colitis were older (P = .0001) and had more severe villous atrophy (P = .002) than the celiac disease patients without microscopic colitis. Microscopic colitis was diagnosed after celiac disease in 64% of the patients, simultaneously in 25%, and before celiac disease in 11% (P = .0001). Pancolitis predominated, though 16% had colitis limited to the right colon. Steroid or immunosuppressant therapies were required in 66% of the celiac disease patients with microscopic colitis and given as maintenance therapy to 50% of these patients. Follow-up biopsies revealed that the colitis persisted in 57% of the patients with celiac disease and microscopic colitis, despite improved diarrhea symptoms; the diarrhea resolved in most of the patients.

CONCLUSIONS

Microscopic colitis is more common in patients with celiac disease than in the general population. Patients with celiac disease and microscopic colitis have more severe villous atrophy and frequently require steroids or immunosuppressant therapies to control diarrhea.

Lymphocytic disorders of the gastrointestinal tract: a review for the practicing pathologist

Increased numbers of intraepithelial lymphocytes (lymphocytosis) can be found in the esophagus, stomach, small intestine, and colon in a variety of clinical circumstances. This review, directed at practicing pathologists, portrays the normal resident lymphocyte population in the mucosa of each segment of the digestive tract and discusses the different situations that may result in quantitative or qualitative alterations of intraepithelial lymphocytes. Esophageal lymphocytosis has not been fully characterized and its clinical significance, if any, awaits definition. Thus, this diagnosis is presently discouraged. In the stomach, it is particularly important to exclude Helicobacter pylori infection and celiac sprue before diagnosing lymphocytic gastritis. Duodenal lymphocytic infiltrates, inextricably tied with alterations of the villous architecture of the mucosa, are often caused by gluten sensitivity. However, similar morphologic changes may be caused by a vast array of other conditions that must be carefully considered and excluded. Lymphocytic and collagenous colitis are most often unexplained, but their frequent association with autoimmune conditions or certain medications deserve a thorough investigation in each case. Using a combination of histologic and clinical clues, a cause for the intraepithelial lymphocytic infiltration can be identified in many instances. As some of the associated conditions are amenable to effective treatment, the importance of diligently seeking such associations before resorting to a diagnosis of primary lymphocytosis is emphasized.

Paucicellular lymphocytic colitis: is it a minor form of lymphocytic colitis? A clinical pathological and immunological study

OBJECTIVES

It has been suggested that paucicellular lymphocytic colitis (PLC) should be considered to be part of the morphological spectrum of microscopic colitis. The aim of the study was to evaluate whether PLC may be considered to be a true microscopic colitis, and in this case, whether it is a minor form of lymphocytic colitis (LC) or a different entity.

METHODS

All incident cases of PLC, LC, and collagenous colitis (CC) during the period 2004-2006 were included. The incidence rate and the clinical, histopathological, and immunological features of PLC were assessed and compared with those of both LC and CC. Immunoreactivities to CD25, c-Kit, and FOXP3 in lamina propria were assessed.

RESULTS

In all, 19 patients with CC, 19 with LC, and 26 with PLC were identified. CD25+FOXP3+ expression was seen only in classical forms of microscopic colitis: 12 of 19 LC, 14 of 20 CC, and none of 20 PLC cases (P < 0.0001). Diarrhea ceased in 21 of the 26 patients, with a decrease in the daily stool number from 5.08 +/- 0.44 to 1.7 +/- 0.2 (P < 0.005). The five patients with no response to therapy fulfilled the Rome II criteria of irritable bowel syndrome (IBS).

CONCLUSIONS

The incidence rate of PLC, identified using objective histological criteria, was higher than those of CC and LC. The lack of expression of CD25+FOXP3+ cells in PLC, in contrast to those seen in both LC and CC, would suggest the existence of different pathophysiological mechanisms and does not support that PLC is a minor form of LC.

Microscopic colitis with giant cells: a clinico-pathological review of 11 cases and comparison with microscopic colitis without giant cells

AIM

To document clinical and pathological features of microscopic colitis with giant cells (MCGC) which is one of a number of atypical variants of microscopic colitis.

METHODS

Cases of microscopic colitis were assessed for giant cells during routine reporting and retrieved from the slide file at a private laboratory. The histological features and clinical data were assessed. Histochemistry (trichome and haematoxylin van Gieson) and immunohistochemistry (CD68) was performed to characterise the nature of the giant cells.

RESULTS

Giant cells were identified in 11 cases of microscopic colitis. The histological features of MCGC are not significantly different from usual MC except for the presence of multinucleated giant cells in the superficial lamina propria. Apart from the common but not unexpected association with autoimmune disease, no unique clinical features of the MCGC group were identified versus those described in the literature for ordinary MC. Immune disorders included gluten-sensitive enteropathy, systemic lupus erythematosus and raised titres of antinuclear antibodies.

CONCLUSIONS

The giant cells have the same immunohistochemical characteristics as histiocytes and appear to form through histiocyte fusion. The presence of giant cells does not appear to confer any further clinical significance and remains a histological curiosity.

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.

[A case of giant cell microscopic colitis?]

Microscopic colitis is the most common cause of chronic watery diarrhea, with normal mucosal appearance during colonoscopy. The diagnosis is made by pathological examination of biopsy specimens showing colitis with normal architecture of the mucosa. The two most frequent forms of microscopic colitis are lymphocytic colitis and collagenous colitis, but other atypical variants have been described. We report a case of lymphocytic colitis with multinucleated large cells and we discuss a variant of giant cells microscopic colitis.

Pitfalls and errors in the diagnosis of collagenous and lymphocytic colitis

The diagnosis of both CC and LC is based on a compatible clinical picture and well-established objective histological criteria. The motivation degree of the involved physicians is essential in the diagnosis of microscopic colitis. The gastroenterologist should refer every patient with chronic watery diarrhea to perform a colonoscopy in spite of the benign course of the disease and the absence of alarm symptoms or signs. The endoscopist should take multiple stepwise biopsy samples of the colonic mucosa despite that the mucosa looked macroscopically normal. Finally, the pathologist should be motivated to use objective histological criteria to make the diagnosis. In this context, it is important to define the terminology as clearly as possible to avoid confusion.

Colonic perforation as a complication of collagenous colitis in a series of 12 patients

OBJECTIVES

The rare complication of colonic perforation in collagenous colitis following colonoscopy or barium enema is reported in this series of 12 patients.

METHODS

Patients with collagenous colitis complicated by perforation were collected from the authors' consultation files between 1992 and 2007. Colectomy and biopsy specimens were reviewed and the corresponding clinical data were analyzed.

RESULTS

The patients ranged in age from 44 to 80 yr, with a female-to-male ratio of 11:1. Perforation occurred during colonoscopy in 2 patients, within 0-5 days following colonoscopy in 8 patients, and during barium enema in 2 patients. The most notable colonoscopic findings were bleeding linear ulcers of the right colon in 9 patients, several of which developed under direct visualization during endoscopy. The perforation culminated in right hemicolectomy in 11 patients. Linear fissuring ulcers were identified in the resections of 8 patients along with features of perforation, including pneumatosis in 4 patients and barium extravasation within the muscularis propria in 2 patients.

CONCLUSIONS

This is the largest published series to date, and the first to uncover several novel clinicopathologic features of perforation in collagenous colitis, including the right colonic predilection (corresponding to disease severity), the association with not only colonoscopy, but also barium enema, the occurrence of recognizable perforation actually developing during the procedure, and a more detailed information on the marked histologic severity of these patients' collagenous colitis. An awareness of this rare but potentially fatal complication of collagenous colitis may facilitate its diagnosis and management.

Colon-targeted delivery of live bacterial cell biotherapeutics including microencapsulated live bacterial cells

There has been an ample interest in delivery of therapeutic molecules using live cells. Oral delivery has been stipulated as best way to deliver live cells to humans for therapy. Colon, in particular, is a part of gastrointestinal (GI) tract that has been proposed to be an oral targeted site. The main objective of these oral therapy procedures is to deliver live cells not only to treat diseases like colorectal cancer, inflammatory bowel disease, and other GI tract diseases like intestinal obstruction and gastritis, but also to deliver therapeutic molecules for overall therapy in various diseases such as renal failure, coronary heart disease, hypertension, and others. This review provides a comprehensive summary of recent advancement in colon targeted live bacterial cell biotherapeutics. Current status of bacterial cell therapy, principles of artificial cells and its potentials in oral delivery of live bacterial cell biotherapeutics for clinical applications as well as biotherapeutic future perspectives are also discussed in our review.

Chronic colitis associated with HIV infection can be related to intraepithelial infiltration of the colon by CD8+ T lymphocytes

Gastrointestinal complications in AIDS patients with diarrhoea are common clinical manifestations, frequently diagnosed by colonoscopy as non-specific colitis. We retrospectively study colon biopsies diagnosed as chronic colitis associated with HIV (CCH). Biopsies were sorted as patients with AIDS (serum CD4 <200 cell/mm3) but without any clear infectious process (n = 12) and patients without HIV infection (n = 24). There are low numbers of CD4+ T lymphocytes in lamina propria of AIDS patients, but CD8+ T populations in this area appear to be similar in all studied groups, regardless of HIV infection or laboratory evidence of a specific agent. We found the clear evidence of CD8+ T cells infiltration in colonic mucosa in HIV patients with microscopic colitis. An imbalance of lymphocyte subpopulations in the colon, both in the lamina propria and epithelium, could result in an intraepithelial CD8 infiltration, involved in the pathogenesis of CCH in AIDS patients.

Microscopic colitis-defining incidence rates and risk factors: a population-based study

BACKGROUND & AIMS

The burden and determinants of microscopic colitis (MC) in North America are inadequately defined. We determined the incidence rate of and risk factors for MC in a well-defined North American population.

METHODS

A population-based cohort study was conducted between April 1, 2002, and March 31, 2004. All adults with a pathologic diagnosis of MC were identified and comprehensive chart review was undertaken to confirm the diagnosis and identify risk factors. Category-specific risks for developing MC were reported as rate ratios (RRs) with exact 95% confidence intervals (CIs).

RESULTS

MC was identified in 164 individuals for an annual incidence rate of 10.0 per 100,000 person-years (lymphocytic colitis, 5.4; collagenous colitis, 4.6 per 100,000). Patients older than the age of 65 were more than 5 times more likely to develop MC (RR, 5.6; 95% CI, 4.0-7.7). Women were at higher risk of acquiring MC for both collagenous colitis (RR, 3.44; 95% CI, 2.07-5.97) and lymphocytic colitis (RR 6.29; 95% CI, 3.21-13.74). Elderly women with a history of malignancy were associated with a higher risk of MC (RR, 3.59; 95% CI, 1.68-7.01), as were patients with celiac disease (RR, 7.9; 95% CI, 4.0-14.2) and hypothyroidism (RR, 6.1; 95% CI, 3.5-10.0).

CONCLUSIONS

This was a large population-based cohort study of MC and our incidence rates were consistent with previously reported population-based studies in North America and Europe. An increased incidence of MC was observed in several disease states with the novel finding of an increased risk of MC with malignancy.

Systematic review: microscopic colitis

BACKGROUND

Collagenous and lymphocytic colitis are fairly common causes of chronic non-bloody diarrhoea, especially in elderly female.

AIM

To present a systematic review of microscopic colitis.

METHODS

A PubMed search using the MeSH terms microscopic colitis, collagenous colitis, lymphocytic colitis and chronic diarrhoea was performed.

RESULTS

Annual incidence of each disorder is 4-6/100,000 inhabitants. The aetiology is unknown. Clinical characteristics are well described and there is an association with autoimmune diseases. Budesonide is the best-documented short-term treatment of collagenous colitis. In meta-analysis pooled odds ratio for clinical response after 6-8 weeks of treatment was 12.3 (95% CI: 5.5-27.5) in comparison with placebo. The evidence for bismuth subsalicylate is weaker and the effectiveness of other alternatives such as loperamide, cholestyramine, aminosalicylates, probiotics, or Boswellia serrata extract is unknown. Although unproven, in unresponsive severe disease azathioprine or methotrexate may be tried. No controlled trials have been carried out in lymphocytic colitis. The long-term prognosis of microscopic colitis is good, serious complications are rare and there is no increased mortality.

CONCLUSIONS

Clinical and epidemiological aspects of microscopic colitis are well described. Budesonide is the best-documented short-term therapy in collagenous colitis, but the optimal long-term strategy needs further study. Controlled treatment data of lymphocytic colitis are awaited for.