In this case, the presence of thickening of the subepithelial collagen layer, more evident with Masson's trichrome (special stain that allows differentiation of the collagen fibers), is pathognomonic of collagenous colitis. Atrophy together with epithelial denudation are characteristic of this disease, which does not usually cause macroscopic alterations of the mucosa. An increased density of intraepithelial lymphocytes and the absence of mention of architectural alterations of the crypts (characteristic of ulcerative colitis and Crohn's disease) support this diagnosis.

A 59-year-old woman presenting with chronic watery diarrhea of 4 months' evolution. In the endoscopy, the mucosa did not show relevant aspects. In particular, no ulcers or friable areas were observed. A biopsy of the transverse colon was performed. Histopathology revealed a thickened area below the superficial lining epithelium, which was more evident by Masson's trichrome technique and involved epithelial atrophy and denudation. There was also a clear increase in intraepithelial lymphocyte density. The diagnosis of the intestinal lesion is?

[Evolution of ideas on microscopic colitis].

The literature review gives the present-day views of the definition, etiology, pathogenesis, diagnosis, and treatment of microscopic colitis (MC). In the present view, MC is an inflammatory bowel disease of unknown etiology, which is characterized by chronic watery diarrhea, no macroscopic signs of large bowel involvement in the presence of specific pathomorphological changes. There are two major forms of MC, which are similar in its clinical picture, yet, heterogeneous in histological criteria: collagenous colitis (CC) and lymphocytic colitis (LC). As of now, the prevalence of MC is about 100 cases per 100,000 population, which is similar with that in other inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease. MC generally prevails in women aged over 50 years. The etiology and pathogenesis of MC have not fully investigated. Watery diarrhea is as a predominant pathognomonic symptom in all the patients with MC. The major histological criterion for the diagnosis of CC is subepithelial collagen lining thickening (more than 10 pm) and that for LC is higher intraepithelial lymphocyte counts (more than 20 intraepithelial lymphocytes/100 epitheliocytes). The topical glucocorticosteroid budesonide is currently the only agent, the efficacy of which has been proven in both inducing and maintaining remission in patients with MC in many clinical trials.

[Microscopic colitis - review].

Microscopic colitis (MC) is an encompassing term for two diseases; collagenous colitis and lymphocytic colitis. The colon appears normal by colonoscopy and a diagnosis is only obtained with a biopsy. The histopathology of collagenous colitis is mainly characterized by a thickening of the subepithelial basement membrane of the colonic mucosa with a band of collagen. Lymphocytic colitis is mainly characterized by an intraepithelial lymphocytosis without the collagen thickening. Even though the two diseases have a distinctive pathology their clinical symptoms are characterized by chronic watery diarrhea without bleeding. Microscopic colitis is thought to cause about 4-13% of all chronic diarrhea but their relative frequency is much higher among older people. The mean annual incidence for collagenous and lymphocytic colitis has been increasing. Steroids are the most effective treatment for microscopic colitis and budesonide is the most studied and effective therapy for MC. The aim of this paper is to give a review of two relatively new diseases which are among the most common cause of chronic diarrhea, especially among older people.

[Are lymphocytic and collagenous colitis two forms of a single disease? Arguments taken from a biopsy quantitative study].

Collagenous colitis and lymphocytic colitis are defined by a clinicopathologic syndrome with chronic watery diarrhea, microscopic lesions of colonic biopsies, and normal barium enema and colonoscopy. A histopathological study was performed on multiple colorectal biopsies to compare 12 cases of collagenous colitis (defined by a subepithelial collagen thicker than 10 microns) and 7 cases of lymphocytic colitis (defined by a number of intraepithelial lymphocytes more than 20 per 100 epithelial cells at least in one biopsied site). The study included a semiquantitative analysis of inflammatory infiltrate in the lamina propria, crypts distortion and epithelial detachment. The number of intraepithelial lymphocytes per 100 epithelial cells was determined in surface epithelium and crypts. The subepithelial collagen thickening was studied by computerised morphometry. The intraepithelial lymphocytes, villous atrophy and thickness of the subepithelial collagen were also determined in gastric and duodenal biopsies. In collagenous colitis, the subepithelial collagenous thickness ranged from 10 to 40 microns in the colon (median 20.99 microns). In 4 cases of collagenous colitis, no thickening of the collagen plate was seen in the rectum. We found constant epithelial detachment and mucosal distortion. In lymphocytic colitis, the thickness of the subepithelial collagen ranged from 6 to 10 microns in 4 cases and was less than 6 microns in 3 cases (median 6.24 microns). The median number of intraepithelial lymphocytes in surface epithelium was 22.35 (range 18.2 to 40) in lymphocytic colitis versus 12.22 (range 4.6 to 24.4) in collagenous colitis. In conclusion, we observed an overlap of both the collagenous plate thickness and the number of intraepithelial lymphocytes in collagenous colitis and lymphocytic colitis. This result favours a unified histogenesis for these two entities.

[Microscopic colitis: pathogenesis].

Microscopic colitis (MC) is a chronic inflammatory process observed in colon biopsies of patients with chronic aqueous diarrhea. It is called microscopic because diagnosis is determined by histological studies since the microscopic characteristics of the colon endoscopy are normal. Two patterns exist: Lymphocytic Microscopic Colitis and Collagenous Microscopic Colitis. Etiology is unknown, and the proposed pathogenic mechanisms indicate an immunological phenomenon. Based on this, the authors of this study hypothesize that lymphocytic infiltration of the lamina propria could be related to cytotoxic lymphocytes CD8 as causative agents of colon tissue damage. Prove hypothesis of immunological pathogenesis of MC. APPARATUS AND METHODS: Thirty eight (38) patients with diagnosed MC were recruited for the last four years in the Pathology Laboratory at Ricardo Palma University. Twenty two (22) colon biopsies with the most severe histological lesions were selected. These biopsies were obtained from 17 patients: 5 patients had 2 biopsies in 2 colonoscopy sessions. Biopsies were fixed in neutral formaldehyde, processed through the paraffin inclusion method, and stained with hematoxiline-eosine and Masson trichromic to distinguish collagenous tissue. Immunohistochemistry was conducted in 4- or 5-micron-thick histological sections processed through the immunoperoxidase method. Nineteen (19) biopsies corresponded to Lymphocytic MC and 3 to Collagenous MC. Lymphocytic MC showed intraepithelial lymphocytosis, dystrophic epithelial damage in the areas of lymphocytic infiltration, lamina propria inflammation with lymphocytes and plasma cells, and normal basement membrane. Collagenous MC showed thickened basement membrane due to the presence of a collagenous band, mild to moderate intraepithelial lymphocytosis, vacuolization,and frequent detachment of protective epithelium. Twenty two (22) biopsies were positive in the immunohistochemical studies.

Lymphocytic, collagenous and other microscopic colitides: pathology and the relationship with idiopathic inflammatory bowel diseases.

Collagenous colitis and lymphocytic colitis are the two major conditions characterized by chronic watery diarrhoea, without endoscopic or radiological lesions, but with histological abnormalities and therefore considered as "microscopic colitis". The histology of colonic biopsies shows inflammation of the mucosa, and either thickening of the subepithelial collagen band or an increase of lymphocytes in the surface epithelium. Different variant forms have been reported under separate names. These are probably not specific entities. The incidence of microscopic colitis is slightly less than the incidence of chronic idiopathic inflammatory bowel diseases (IBD). Microscopic colitis and IBD are clearly different entities. The relation between both entities is weak but double. Biopsy samples from patients with IBD may mimic the features of lymphocytic or collagenous colitis, both in the initial onset and during follow-up. In the large majority of these cases, endoscopy shows or has shown mucosal lesions. In rare cases, however, a double diagnosis was made. Certain patients, usually of older age, presented first with a microscopic, usually collagenous colitis and developed subsequently genuine ulcerative colitis.

Histopathological diagnosis of microscopic colitis.

A typical symptom of microscopic colitis (MC) is chronic watery diarrhea with normal endoscopic findings and characteristic inflammatory changes in histopathology. Treatment of the disease is mainly empiric. MC has two main subtypes: lymphocytic colitis and collagenous colitis. There are also untypical histopathological forms of MC: MC with giant cells, MC not otherwise specified (NOS) and cryptal lymphocytic coloproctitis. Some other histopathological changes in MC have been observed, especially Paneth cell hyperplasia or epithelial degeneration. Eosinophilic colitis, acute colitis, amyloidosis, ulcerative colitis and Crohn's disease should be taken into consideration in differential diagnosis. The most reliable biopsy material for histopathological examination are samples obtained from transverse colon. Some studies proved that treatment of MC makes it possible to reduce not only clinical, but also histopathological, manifestations.

Microscopic colitis

Diagnosis Colonoscopic appearances are normal or near normal. As the changes are often patchy, an examination limited to the rectum may miss cases of microscopic colitis, and so a full colonoscopy is necessary. Multiple colonic biopsies are taken in order to make the diagnosis. Histological features of colonic biopsies indicating microscopic colitis are: greater than 20 intraepithelial lymphocytes per 100 epithelial cells and, additionally, 10-20 μm of a thickened subepithelial collagen band in collagenous colitis. Inflammation of the lamina propria, with mainly mononuclear cells, may be observed in collagenous colitis.

Ulcerative colitis

The simple clinical colitis activity index was created in 1998 and is used to assess the severity of symptoms. Endoscopic The best test for diagnosis of ulcerative colitis remains endoscopy, which is examination of the internal surface of the bowel using a flexible camera. Initially, a flexible sigmoidoscopy may be completed to establish the diagnosis. The physician may elect to limit the extent of the initial exam if severe colitis is encountered to minimize the risk of perforation of the colon. However, a complete colonoscopy with entry into the terminal ileum should be performed to rule out Crohn's disease, and assess extent and severity of disease. Endoscopic findings in ulcerative colitis include: erythema (redness of the mucosa), friability of the mucosa, superficial ulceration, and loss of the vascular appearance of the colon. When present, ulcerations may be confluent. Pseudopolyps may be observed.

The role of mucosal biopsy in the diagnosis of chronic diarrhea: value of multiple biopsies when colonoscopic finding is normal or nonspecific.

There are controversies about taking routine mucosal biopsy when the gross colonoscopic finding is normal. This study was conducted to determine the frequency of clinically important histological abnormalities, prospectively, in chronic diarrhea patients with grossly normal or nonspecific colonoscopic findings. One hundred and eighteen patients suffering from nonbloody diarrhea with average frequency of more than two times a day for more than 4 weeks were included. Multiple biopsies (cecum, ascending colon, mid-transverse colon, descending colon, sigmoid colon and rectum) were taken during colonoscopic examinations and each biopsy specimen was reviewed by one pathologist after H&E and Masson-trichrome staining. Clinically significant abnormalities (2 collagenous colitis, 1 lymphocytic colitis, 1 eosinophilic enterocolitis, 1 ulcerative colitis and 4 melanosis coli) were observed in 9 patients (7.6%). Sixteen cases (13.6%) of borderline histological abnormalities were observed (8 cases of possible collagenous colitis and 8 cases showing some features of lymphocytic colitis). Ninety two cases (78.8%) showed nonspecific inflammation only. Clinically important histological lesions can exist in significant percentage in spite of normal or nonspecific colonoscopic findings, which can justify routine mucosal biopsy in the evaluation of chronic diarrhea patients. The clinical significance of borderline histological abnormalities needs to be determined by careful follow-up studies.

Endoscopic findings and colonic perforation in microscopic colitis: A systematic review.

Microscopic colitis (MC) is a clinical syndrome of severe watery diarrhea with few or no endoscopic abnormalities. The incidence of MC is reported similar to that of other inflammatory bowel diseases. The need for histological confirmation of MC frequently guides reimbursement health policies. With the advent of high-definition (HD) coloscopes, the incidence of reporting distinct endoscopic findings in MC has risen. This has the potential to improve timely diagnosis and cost-effective MC management and diminish the workload and costs of busy modern endoscopy units. Publications on distinct endoscopic findings in MC available until March 31st, 2017 were searched systematically (electronic and manual) in PubMed database. The following search terms/descriptors were used: collagenous colitis (CC) OR lymphocytic colitis (LC) AND endoscopy, colonoscopy, findings, macroscopic, erythema, mucosa, vasculature, scars, lacerations, fractures. An additional search for MC AND perforation was made. Eighty (n=80) articles, predominantly single case reports (n=49), were found. Overall, 1582 (1159F; 61.6±14.1 years) patients (pts) with MC and endoscopic findings were reported. The majority of articles (n=62) were on CC (pts 756; 77.5% females). We identified 16 papers comprising 779 pts (69.2% females) with LC and 7 articles describing 47 pts (72.3% females) diagnosed as MC. The youngest patient was 10 and the oldest a 97-year-old. Aside diarrhea, symptoms included abdominal pain, weight loss, bloating, flatulence, edema and others. In the study group we found 615 (38.8%) persons with macroscopic lesions in gut. Isolated linear ulcerations were identified in 7 pts (1.1%) while non-ulcerous lesions i.e. pseudomembranes, a variable degree of vasculature pruning & dwindling, mucosal lacerations and abnormalities such as erythema/edema/nodularity, or surface textural alteration in 608 pts (98.1%). The location of endoscopic findings was not reported in 27 articles. The distinct endoscopic findings were described in the left (descending, sigmoid, rectum - 10/21/11 studies), right (cecum, ascending - 7/7 studies), transverse colon (n=12), as well as duodenum (n=4), and terminal ileum (n=2). In 17 (1.1%) pts colonic perforation occurred. Endoscopic findings are recognized with increased frequency in pts with MC. This could improve MC diagnosis by prompting a more extensive biopsy protocol in such cases and an earlier initiation of treatment. Procedure-related perforation has been reported in this group; therefore, cautious air insufflation is advisable when endoscopic findings are recognised.

Microscopic colitis

Pathology Microscopic colitis is characterized by an increase in inflammatory cells, particularly lymphocytes, in colonic biopsies with an otherwise normal appearance and architecture of the colon. Inflammatory cells are increased both in the surface epithelium ("intraepithelial lymphocytes") and in the lamina propria. The key feature is more than 20 intra-epithelial lymphocytes per 100 epithelial cells. These are the principal features of lymphocytic colitis. An additional distinguishing feature of collagenous colitis is a thickened subepithelial collagen layer, which may be up to 30 micrometres thick, that occurs in addition to the features found in lymphocytic colitis. The fact that the two types of microscopic colitis share many features including epidemiology, risk factors and, response to therapy has led to the suggestion that they are actually subtypes of the same disease.

Lymphocytic colitis

Lymphocytic colitis is a subtype of microscopic colitis, a condition characterized by chronic non-bloody watery diarrhea. Causes No definite cause has been determined. The peak incidence of lymphocytic colitis is in persons over age 50; the disease affects women and men equally. Some reports have implicated long-term usage of NSAIDs, proton pump inhibitors, and selective serotonin reuptake inhibitors, and other drugs. Associations with other autoimmune disorders suggests that overactive immune responses occur. Diagnosis The colonoscopy is normal but histology of the mucosal biopsy reveals an accumulation of lymphocytes in the colonic epithelium and connective tissue (lamina propria). Collagenous colitis shares this feature but additionally shows a distinctive thickening of the subepithelial collagen table.

Ulcerative colitis

Ulcerative colitis is usually continuous from the rectum, with the rectum almost universally being involved. Perianal disease is rare. The degree of involvement endoscopically ranges from proctitis (rectal inflammation) to left sided colitis (extending to descending colon), to extensive colitis (extending proximal to descending colon). Histologic Biopsies of the mucosa are taken during endoscopy to confirm the diagnosis of UC and differentiate it from Crohn's disease, which is managed differently clinically. Histologic findings in ulcerative colitis includes: distortion of crypt architecture, crypt abscesses, and inflammatory cells in the mucosa (lymphocytes, plasma cells, and granulocytes). Unlike the transmural inflammation seen in Crohn's disease, the inflammation of ulcerative colitis is limited to the mucosa.

Colitis

An important investigation in the assessment of colitis is biopsy. A very small piece of tissue (usually about 2mm) is removed from the bowel mucosa during endoscopy and examined under the microscope by a histopathologist. It can provide important information regarding the cause of the disease and the extent of bowel damage. Types There are many types of colitis. They are usually classified by the cause. Types of colitis include: Autoimmune Inflammatory bowel disease (IBD) – a group of chronic colitides. Ulcerative colitis (UC) – a chronic colitis that affects the large intestine. Crohn's disease (CD) – another type of IBD that often leads to colitis. Unknown Microscopic colitis – a colitis diagnosed by microscopic examination of colonic tissue; macroscopically ("to the eye") it appears normal. Lymphocytic colitis Collagenous colitis Treatment-caused Diversion colitis Chemical colitis Chemotherapy-induced colitis Radiation colitis Checkpoint inhibitor induced colitis

Segmental colitis associated with diverticulosis

Types There are four types of SCAD, based on endoscopic appearance. Pattern A is characterized by involvement of crescentic folds and is the most common type of SCAD (52%). Pattern B has an appearance similar to mild-to moderate ulcerative colitis (30.40%), whereas pattern C appears similar to Crohn's disease (10.90%). Pattern D is the least common, and appears similar to severe ulcerative colitis (6.50%). Diagnosis SCAD is diagnosed via colonoscopy, often incidentally during examination for unrelated concerns. Colonoscopy shows erythema of the colonic mucosa, which may be characterized by friability and exudate. The descending and sigmoid colon are typically involved. Biopsies of the affected area and the unaffected rectum confirm the diagnosis. Biopsies of SCAD show evidence of chronic inflammation. Rectal biopsies show normal mucosa.

Microscopic colitis

Microscopic colitis refers to two related medical conditions which cause diarrhea: collagenous colitis and lymphocytic colitis. Both conditions are characterized by the presence of chronic non-bloody watery diarrhea, normal appearances on colonoscopy and characteristic histopathology findings of inflammatory cells. Signs and symptoms The main symptom is persistent non-bloody watery diarrhea, which may be profuse. People may also experience abdominal pain, fecal incontinence, and unintentional weight loss. Microscopic colitis is the diagnosis in around 10% of cases investigated for chronic non-bloody diarrhea.

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.

Ulcerative colitis

The clinical presentation of ulcerative colitis depends on the extent of the disease process. Up to 15% of individuals may have severe disease upon initial onset of symptoms. A substantial proportion (up to 45%) of people with a history of UC without any ongoing symptoms (clinical remission) have objective evidence of ongoing inflammation. Ulcerative colitis is associated with a generalized inflammatory process that can affect many parts of the body. Sometimes, these associated extra-intestinal symptoms are the initial signs of the disease. Extent of involvement In contrast to Crohn's disease, which can affect areas of the gastrointestinal tract outside of the colon, ulcerative colitis is usually confined to the colon. Inflammation in ulcerative colitis is usually continuous, typically involving the rectum, with involvement extending proximally (to sigmoid colon, ascending colon, etc). In contrast, inflammation with Crohn's disease is often patchy, with so-called "skip lesions."

Inflammatory bowel disease

No disease specific markers are currently known in the blood, enabling the reliable separation of Crohn's disease and ulcerative colitis patients. The way doctors can tell the difference between Crohn's disease and UC is the location and nature of the inflammatory changes. Crohn's can affect any part of the gastrointestinal tract, from mouth to anus (skip lesions), although a majority of the cases start in the terminal ileum. Ulcerative colitis, in contrast, is restricted to the colon and the rectum. Microscopically, ulcerative colitis is restricted to the mucosa (epithelial lining of the gut), while Crohn's disease affects the full thickness of the bowel wall ("transmural lesions"). Lastly, Crohn's disease and ulcerative colitis present with extra-intestinal manifestations (such as liver problems, arthritis, skin manifestations and eye problems) in different proportions.

[Microscopic colitis: histopathological review with a clinicopathological correlation].

Microscopic colitis is a clinicopathological entity which, in addition to typical symptoms such as watery diarrhea, is characterized by its specific histopathology. Since colonoscopy yields normal findings, microscopic colitis belongs in a histological domain. The term encompasses two forms: lymphocytic and collagenous colitis. Histologically, lymphocytic colitis shows an increase in intraepithelial lymphocytes of more than 20 lymphocytes per 100 surface colonocytes, while collagenous colitis is characterized by a thickened subepithelial collagen layer of more than 10 µm. Specific stains help in the quantification of both. Since microscopic colitis does not always affect the entire colon and the number of intraepithelial lymphocytes varies physiologically, obtaining stepwise biopsies of the colon (with information on location where possible) is recommended. A thickened collagen layer is relatively specific for collagenous colitis, whereas intraepithelial lymphocytosis is also found in other diseases. Therefore, to make a correct diagnosis, it is important to correlate histological findings with clinical symptoms, including the main symptom of watery diarrhea.

Collagenous colitis

Collagenous colitis is an inflammatory bowel disease affecting the colon specifically with peak incidence in the 5th decade of life, affecting women more than men. Its clinical presentation involves watery diarrhea in the absence of rectal bleeding. It is often classified under the umbrella entity microscopic colitis, that it shares with a related condition, lymphocytic colitis. Signs and symptoms Microscopic colitis causes chronic watery diarrhea with greater than 10 bowel movements per day. Some patients report nocturnal diarrhea, abdominal pain, urgency, fecal incontinence, fatigue, dehydration and weight loss. Patients report a significantly diminished quality of life. Causes The cause of collagenous colitis is unknown.

Pitfalls in the diagnosis of collagenous colitis: experience with 75 cases from a registry of collagenous colitis at the Johns Hopkins Hospital.

Collagenous colitis is a relatively rare disorder presenting mainly in middle-aged women as watery diarrhea. Endoscopic and radiographic studies of the colon are usually normal, and diagnosis must be made by biopsy. The characteristic biopsy findings are a combination of increased mucosal inflammation (collagenous colitis) as well as subepithelial collagenous thickening. The mucosal inflammatory changes include increased lamina propria plasma cells, prominent intraepithelial lymphocytes, and in some cases, numerous eosinophils. The collagenous thickening has qualitative as well as quantitative differences from normal, and may be highlighted by Masson trichrome stains. Simply quantitating the thickness of a subepithelial collagen layer is neither adequate nor necessary for the diagnosis of collagenous colitis. Major problems in diagnosing collagenous colitis arise from focusing solely on the subepithelial region without attention to inflammatory changes. For example, tangential sectioning of normal colon results in an artifactually thickened basement membrane, and such cases have been wrongly interpreted as collagenous colitis. If biopsies lack the characteristic inflammatory pattern, a tangentially cut thick basement membrane should be ignored. The key to correct diagnosis of collagenous colitis is analyzing the summation of various inflammatory changes plus subepithelial collagenization, rather than focusing on any single feature in isolation.

Evolution of collagenous colitis into severe and extensive ulcerative colitis.

Collagenous colitis is an inflammatory mucosal disorder of the colon with distinctive histopathological features, including a thickened subepithelial collagen layer. The clinical course is usually benign, but serious complications, including death, may occur. In the present report, a 69-year-old woman with watery diarrhea and collagenous colitis developed bloody diarrhea that was refractory to treatment medications, including corticosteroids and azathioprine. Endoscopic and histopathological studies showed a focal neutrophilic inflammatory process that progressed to a diffuse and extensive form of colitis, eventually requiring total proctocolectomy. Careful histological review of the resected colon showed no evidence of persistent collagenous colitis. These findings suggest an important need for continued long-term follow-up of patients with collagenous colitis because superimposed and serious colonic complications may occur, including a severe and extensive pancolitis refractory to medications and necessitating total proctocolectomy.

[Clinical significance of erosive and/or small ulcerative lesions in the colon and terminal ileum--short-term follow-up study].

Various etiologies and diseases may be related to erosions and/or small ulcers without gross inflammatory changes in the surrounding mucosa found in the colon and terminal ileum during colonoscopy. However, studies on follow-up of these lesions are rare. Thus, we investigated the clinical significance of these lesions and their characteristics helpful for differential diagnosis. We reviewed the data of 183 patients with colonoscopically observed erosive or small ulcerative lesions (<2 cm), and analyzed them according to the location, number, and size of lesions, histopathologic findings, chief complaints, laboratory findings, changes of symptoms, and changes in lesions during 4-12 week follow-up period. Histopathologic findings of these lesions included acute nonspecific inflammation, chronic nonspecific inflammation, Crohn's disease, tuberculous colitis, ischemic colitis, Behcet's disease, cytomegalovirus infection, eosinophilic colitis, ulcerative colitis or pseudomembranous colitis, but most of them were nonspecific (84%). In patients with nonspecific inflammation, histopathologic findings, symptoms, location and multiplicity of the lesions were not prognostic factors for the persistency of symptoms and lesions during follow-up period. Two patients with acute inflammation, who showed no improvement in symptoms and lesions, were later diagnosed as Crohn's disease. Erosive or small ulcerative lesions without macroscopic inflammatory changes in the surrounding mucosa during colonoscopy, are mainly nonspecific. However, careful follow-up is required when the symptoms and/or lesions are not improved.

Microscopic colitis in patients presenting with chronic diarrhea.

To investigate the prevalence of microscopic colitis among patients presenting with chronic watery diarrhea. Colonic biopsies from 400 patients presenting with chronic watery diarrhea and other symptoms pertaining to lower gastrointestinal tract were studied. After a detailed clinical history and thorough physical examination full length colonoscopy was done using flexible colonoscope. Colonic biopsies were taken from abnormal and normal areas. Three to five micron thick sections were cut and stained with hematoxylin and eosin and Masson's trichrome stain to highlight sub epithelial collagen. Fifteen out of 400 (3.7%) colonic biopsies from patients presenting with chronic diarrhea had evidence of microscopic colitis. Five out of fifteen biopsies (33%) were diagnosed as collagenous colitis, 10 biopsies (67%) had evidence of lymphocytic colitis; 14/400(3.5%) histologically normal biopsies were taken as controls to compare various demographic and risk factors. Ten out of 15 patients (67%) were clinically diagnosed as irritable bowel syndrome. In the remaining five an infective etiology was suspected. On colonoscopy12/15 (80%) had no abnormality and 3/15 (20%) had mild hyperemia. A possibility of microscopic colitis should be considered while examining colonoscopic biopsy of a patient with chronic watery diarrhea and normal colonoscopy to avoid the misdiagnosis that may affect the treatment of patients.

Collagenous and Lymphocytic Colitis -- Introduction

Histologic changes define the two types of microscopic colitis. Often this presentation of symptoms will lead to evaluation for other types of inflammatory bowel disease including Crohn disease and ulcerative colitis. The incidence has been increasing throughout northern Europe and northern North America, which is more common in females. [2]

Microscopic colitis

Epidemiology Incidence and prevalence of microscopic colitis nears those of ulcerative colitis and Crohn's disease. Studies in North America found incidence rates of 7.1 per 100,000 person-years and 12.6 per 100,000 person-years for collagenous colitis for lymphocytic colitis, respectively. Prevalence has been estimated as 103 cases per 100,000 persons. People who develop microscopic colitis are characteristically, though not exclusively, middle-aged females. The average age of diagnosis is 65 but 25% of cases are diagnosed below the age of 45. History The condition of microscopic colitis was first described as such in 1982. Lymphocytic colitis was described in 1989. Collagenous colitis was recognised earlier, in 1976. References External links MayoClinic.com Colitis Steroid-responsive inflammatory conditions

Microscopic colitis: Common cause of unexplained nonbloody diarrhea.

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

Pancolitis

Pancolitis, in its most general sense, refers to inflammation of the entire colon. This can be caused by a variety of things. Pancolitis or universal colitis is frequently used in a more specific fashion to denote a very severe form of ulcerative colitis. This form of ulcerative colitis is spread throughout the entire large intestine including the right colon, the left colon, the transverse colon, descending colon, and the rectum. A diagnosis can be made using a number of techniques but the most accurate method is direct visualization via a colonoscopy. Symptoms are similar to those of ulcerative colitis but more severe and affect the entire large intestine. Patients with ulcerative colitis generally exhibit symptoms including rectal bleeding as a result of ulcers, pain in the abdominal region, inflammation in varying degrees, and diarrhea (often containing blood). Pancolitis patients exhibit these symptoms and may also experience fatigue, fever, and night sweats. Due to the loss of

[Ulcerative colitis with segmental involvement].

Ulcerative colitis is a chronic inflammatory disease affecting areas of the colon or the full length. From the endoscopic point of view, ulcerative colitis presents lesions that stretch continuously from the rectum to variable colon segments, a characteristic that is of great value when distinguishing it from Crohn's disease. Continuous involvement, without healthy patches, justifies ending endoscopic exploration once the distal end of the lesion has been reached. To retrospectively study the frequency of segmental lesions in the colonoscopies performed in patients with ulcerative colitis. Diagnosis of ulcerative colitis and proctitis was established by clinical, endoscopic, histologic, analytical, and radiological criteria. The indication and number of endoscopies was made on the basis of the clinical criteria of diagnosis, acute episodes, refractoriness or dysplasia screening. The extent of the examination also depended on clinical criteria: the severity of the episode, tolerance to colonoscopy or the degree of cleansing. A total of 155 coloscopies were performed. In 113 colonoscopies (73%) the distal end of the lesion was reached and in 70 (45%) the cecum was reached. Of the 80 patients, 27 (33%) presented ulcerative proctitis at diagnosis. Nine of the 80 patients (11.3%) biopsies were performed in healthy colonic patches, which confirmed histological normality. Six of the 9 patients were receiving no treatment. In all patients except two, the cecum was reached in one or more of the colonoscopies. The distribution of the segmental lesions varied but these were mainly found in the periappendicular region and in the cecum in 6 of the 7 patients in whom the cecum was reached. Of the 80 patients, endoscopic evidence of rectal sparing was found in 5 (6.3%); of these, 4 were receiving systemic or topical treatment. Histological analysis confirmed the absence of inflammatory lesions in these patients. The only patient who was not receiving treatment presented microscopic lesions compatible with ulcerative colitis. Endoscopic segmental lesions in ulcerative colitis were present in 11.3% of patients. Segmental lesions were most frequently found in the cecum and periappendicular region. Endoscopic and histologic evidence of rectal sparing may be the result of systemic or topical treatment.

InternalMed_Harrison

FIGURE 345-5 Colonic polyps. A. Pedunculated colon polyp on a thick stalk covered with normal mucosa (arrow). B. Sessile rectal polyp. FIGURE 345-4 Causes of colitis. A. Chronic ulcerative colitis with diffuse ulcerations and exudates. B. Severe Crohn’s colitis with deep ulcers. C. Pseudomembranous colitis with yellow, adherent pseudo-membranes. D. Ischemic colitis with patchy mucosal edema, subepithelial hemorrhage, and cyanosis. FIGURE 345-6 Colon adenocarcinoma growing into the lumen. FIGURE 345-7 Flat serrated polyp in the cecum. A. Appearance of the lesion under conventional white-light imaging. B. Mucosal patterns and boundary of the lesion enhanced with narrow band imaging. C. Submucosal lifting of the lesion with dye (methylene blue) injection prior to resection.

[Microscopic colitis].

A 38-year old woman is admitted in the gastroenterology unit for a disabling episode of watery diarrhoea, not bloody and refractory to anti-diarrheic drugs. Different diagnostic exams remain negatives, with the exception of colic biopsies who disclose a lymphocytic colitis, one of the forms of the microscopic colitis entity. Microscopic colitis is an anatomo-clinic syndrome characterized by the presence of histological abnormalities on colic biopsies amongst patients suffering from chronic watery diarrhoea without endoscopic anomalies. Two clinical entities are today well known: collagenous colitis is characterized by a thickening of the sub-epithelial collagen band of the colon; lymphocytic colitis is defined as an increased level of lymphocytic cells, more than 20%, in the epithelial surface of colorectal mucosa. Inflammatory lesions of the chorion and alterations of the epithelial surface are seen in the two types of colitis. Their etiology remains unknown. It could be due to inflammatory lesions from autoimmune origin, activated by various exogenous agents such as bacteria and drugs. Clinical (feminine prevalence, frequent association with auto-immune diseases) and morphological similarities lead to argue and to hypothesis that both entities could represent different stages of the same disease, the lymphocytic colitis being the early stage. Various treatments have been proposed, for instance 5-aminosalicylates, but today mainly synthetic corticoids are used, especially budesonide. Others entities are recently been described: the chronic pericrypt eosinophilic enterocolitis and the colonic epithelial lymphocytosis ("epidemic").