Microscopic colitisK52.9 (Sonstige näher bezeichnete nichtinfektiöse Gastroenteritis und Kolitis)

Lindström 1976; description of lymphocytic colitis by Lazenby 1989

Microscopic colitis is a chronic inflammation of the mucous membrane of the colon, the cause of which is still not known and which is clinically associated with severe watery diarrhoea. With regard to the clinical leading symptom, these forms of disease are also summarised under the generic term "syndrome of watery diarrhoea". Microscopic colitis does not lead to macroscopically conspicuous (i.e. endoscopically visible) changes in the mucosa. However, it is defined by a characteristic histological finding. Thus, the clinical picture is only detectable in fine tissue.

A distinction is made according to the histological picture (Olesen M et al. 2004):

• lymphocytic colitis
• collagenous colitis (collagenous colitis)

In Europe, the lowest incidence (0.6/100,000) is reported for France and the highest (5.2/100,000) for Iceland (2/100,000). According to Swedish studies, the highest incidence rates are found in the group of women, > 60 years, with 26.9/ 100,000. Olesen et al. stated the incidence for Scandinavia at 4.4 per 100,000. For lymphocytic colitis, increasing incidence rates have been found in recent years according to the investigations of Pardi et al. Epidemiological studies from Sweden (Olesen M et al. 2016) and the USA (Pardi DS et al. 2007) unanimously show an increase in incidence rates in recent years. There is an increasing trend.

w:m=5:1.

A multifactorial genesis is assumed; the triggering factors are various Drugs like NSAIDs, paroxetine, omeprazole, simvastatin. Bacterial genesis (detection of Yersinia antibodies)? Autoimmunological genesis (in 25% positive ANA titers)?

Furthermore, genetic factors (HLA determination) are discussed. Different mediators (TGF-beta, VEGF) were described in the context of the inflammatory reaction. The importance of luminal agents is understood by the fact that the formation of an ileostoma histologically leads to a significant reduction of the collagen band.

The median age at diagnosis is 59 (48-70) years.

The main symptom of microscopic colitis is watery diarrhoea (in 100% of cases). Furthermore:

• nocturnal diarrhoea (27%)
• Weight loss (42 %)
• abdominal pain (41%)
• Nausea (21%)
• Meteorism (12 %)

Associated diseases: Sjögren's syndrome, Raynaud's syndrome, rheumatoid arthritis (seropositive/seronegative), psoriasis, sprue, thyroid dysfunction(hyper- or hypothyroidism) and diabetes mellitus have been described. About 10% of the persons were first or second degree relatives of patients with ulcerative colitis, Crohn's disease or celiac disease. In this respect, a genetic component must be discussed.

Collagenous colitis is characterized by a broad subepithelial collagen band (> 10 µm). Furthermore, an inflammatory infiltrate of the tunica propria consists of lymphocytes and plasma cells. In lymphocytic colitis there is a marked increase in intraepithelial T-lymphocytes (CD8+suppressor cells: > 20 intraepithelial lymphocytes per 100 epithelial cells) in the ceiling epithelium of the colonic mucosa. The ceiling epithelium itself is flattened and narrowed. Pathophysiology: The peculiarity of collagenous colitis is the excessive formation of a membrane (physiologically present in every human, but only a few micrometers thick) which normally separates the mucosal epithelial cells from the underlying layers of the intestinal wall. This membrane thickens; it then consists mainly of repair collagen, as occurs, for example, in scar formation.

Colitis of bacterial origin; lactose intolerance, irritable bowel syndrome of the diarrhoea type; Coeliac disease.

Probiotics: The effect of Lactobacillus acidophilus LA5 and Bifidobacterium animalis subspp. lactis BB12 was tested in 29 patients with collagenous colitis in a placebo-controlled study. However, there was no difference between the two treatment regimes.

E. coli extracts: Furthermore, the influence of E. coli extracts (bacterium Escherichia coli, strain Nissle 1917) was investigated in 14 patients with collagenous colitis. In 64 percent of the treated patients, a reduction of stool frequency by more than 50 percent was recorded. The results require further confirmation.

Symptomatic: As symptomatic antidiarrheal measures: loperamide, activated carbon.

First choice therapy is a combination therapy of glucocorticoids and 5-aminosalicylic acid (budesonide or prednisolone and mesalazine). In > 80 % of the patients an improvement of the symptoms occurs under budesonide (Olesen M et al. 2004).

Alternative: TNF-alpha antibodies (Infliximab, Adalimumab)

Alternative: Methotrexate: In analogy to Crohn's disease and ulcerative colitis, methotrexate was also used in patients who were refractory to therapy. In a small group, 14 of 19 patients treated in a retrospective case collection showed a good clinical response. Further studies on methotrexate are necessary.

25% of cases, improvement. 75% of cases recur, sometimes with long symptom-free intervals.

Boswellia serrata (incense). The rationale for using Boswellia serrata is the inhibition of leukotriene synthesis. Madisch et al (2007) were able to prove the effect of incense therapy in a placebo-controlled study. With administration of 3 x 400 mg boswellia serrata extract 63.3 % of the patients were in clinical remission after 6 weeks. The difference to placebo (26.7 %) is statistically highly significant (p=0.04 (Madisch A et al. 2007).

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