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. Differential diagnosis
Differential diagnoses, which should be ruled out, include bile acid diarrhea, lactose malabsorption, celiac disease, Crohns disease, ulcerative colitis, and infectious colitis. Treatment
Lymphocytic and collagenous colitis have both been shown in randomized, placebo-controlled trials to respond well to budesonide, a glucocorticoid. Budesonide formulated to be active in the distal colon and rectum is effective for both active disease and in the prevention of relapse. However, relapse occurs frequently after withdrawal of therapy.Studies of a number of other agents including antidiarrheals, bismuth subsalicylate (Pepto-Bismol), mesalazine/mesalamine (alone or in combination with cholestyramine), systemic corticosteroids, cholestyramine, immunomodulators, and probiotics have shown to be less effective than budesonide for treating both forms of microscopic colitis.Anti-TNF inhibitors.
By using Southern blot analysis of leukocytes, it was revealed that the patients (on average) had expanded repeats ranging from 280 to 380 bp which was the equivalent of more than 90 repeats of CGG, when the LRP12 gene of 1,000 control subjects was tested with the same method, it was revealed that they (on average) had between 13 and 45 repeat units of the same nucleotides, with the exception of two out of the 1,000 controls, who had expanded repeats without any symptoms of the condition.In 2020, Deng et al. discovered beterozygous trinucleotide repeat expansions in the 5-prime untranslayed region of the GIPC1 gene of multiple affected members from 3 Chinese families, this trinucleotide sequence consisted of two Gs (guanine) and one C (cytosine). This mutation was later identified by the same team of researchers in 16 patients, of which 9 were Chinese and 7 were Japanese.In 2020, Ogasawara et al. discovered heterozygous trinucleotide repeat expansions in the non-coding region of the NOTCH2NLC gene of 7 un-related Japanese patients with the condition, the trinucleotide sequence consisted of one C (cytosine) and two Gs (guanine), all 5 patients had more than 100 repeats of the trinucleotide sequence, one of which had two expansions consisting of 217 and 674 repeats. See also
Myopathy
Familial episodic pain syndrome


== References ==