Microscopic colitis
Encyclopedia
Microscopic colitis refers to two medical conditions which cause diarrhea
: collagenous colitis
and lymphocytic colitis
. Both conditions are characterised by the following triad of clinicopathological features:
s. They present with a long history of watery diarrhoea, which may be profuse. There is a higher incidence of autoimmune disease
s, for example arthritis
, Sjögren's syndrome
, and coeliac disease
, in patients with microscopic colitis. There are reports of associations with multiple drugs, especially non-steroidal anti-inflammatory drugs (NSAIDs).
Colonoscopy is normal or near normal. The changes are often patchy, so multiple colonic biopsies must be taken in order to make the diagnosis. A full colonoscopy is required, as an examination limited to the rectum will miss cases of microscopic colitis.
("intraepithelial lymphocytes") and in the lamina propria
. In lymphocytic colitis, these are the only abnormal features.
In collagenous colitis, the features of lymphocytic colitis are present, with in addition the presence of a thickened subepithelial collagen
layer which may be up to 30 micrometre
s thick.
Lymphocytic colitis is thought to respond well to Pepto-Bismol
, mesalazine
and collagenous colitis to budesonide
.
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
: collagenous colitis
Collagenous colitis
Collagenous colitis is an inflammatory colonic disease with peak incidence in the 5th decade of life, affecting women more than men. Its clinical presentation involves watery diarrhea, usually in the absence of rectal bleeding...
and lymphocytic colitis
Lymphocytic colitis
Lymphocytic colitis, a subtype of microscopic colitis, is a rare condition characterized by chronic non-bloody watery diarrhea. The colonoscopy is normal but the mucosal biopsy reveals an accumulation of lymphocytes in the colonic epithelium and connective tissue...
. Both conditions are characterised by the following triad of clinicopathological features:
- Chronic watery diarrhoea;
- Normal colonoscopyColonoscopyColonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...
; - Characteristic histopathologyHistopathologyHistopathology refers to the microscopic examination of tissue in order to study the manifestations of disease...
.
Clinical features
Patients are characteristically, though not exclusively, middle-aged femaleFemale
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...
s. They present with a long history of watery diarrhoea, which may be profuse. There is a higher incidence of autoimmune disease
Autoimmune disease
Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to...
s, for example arthritis
Arthritis
Arthritis is a form of joint disorder that involves inflammation of one or more joints....
, Sjögren's syndrome
Sjögren's syndrome
Sjögren's syndrome , also known as "Mikulicz disease" and "Sicca syndrome", is a systemic autoimmune disease in which immune cells attack and destroy the exocrine glands that produce tears and saliva....
, and coeliac disease
Coeliac disease
Coeliac disease , is an autoimmune disorder of the small intestine that occurs in genetically predisposed people of all ages from middle infancy onward...
, in patients with microscopic colitis. There are reports of associations with multiple drugs, especially non-steroidal anti-inflammatory drugs (NSAIDs).
Colonoscopy is normal or near normal. The changes are often patchy, so multiple colonic biopsies must be taken in order to make the diagnosis. A full colonoscopy is required, as an examination limited to the rectum will miss cases of microscopic colitis.
Pathology
The hallmark of microscopic colitis is an increase in inflammatory cells (i.e. lymphocytes) in colonic biopsies with an otherwise normal appearance and architecture of the colon. Inflammatory cells are increased both in the surface epitheliumEpithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
("intraepithelial lymphocytes") and in the lamina propria
Lamina propria
The lamina propria is a constituent of the moist linings known as mucous membranes or mucosa, which line various tubes in the body ....
. In lymphocytic colitis, these are the only abnormal features.
In collagenous colitis, the features of lymphocytic colitis are present, with in addition the presence of a thickened subepithelial collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
layer which may be up to 30 micrometre
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
s thick.
Treatment
No single treatment is accepted as the standard and measuring response is difficult. Often a trial of anti-diarrhoeals is followed by anti-inflammatory drugs.Lymphocytic colitis is thought to respond well to Pepto-Bismol
Pepto-Bismol
Pepto-Bismol is an over-the-counter drug currently produced by the Procter and Gamble company in the United States of America and in Canada to treat minor digestive system upset. Its active ingredient is bismuth subsalicylate...
, mesalazine
Mesalazine
Mesalazine , also known as Mesalamine or 5-aminosalicylic acid , is an anti-inflammatory drug used to treat inflammation of the digestive tract ulcerative colitis and mild-to-moderate Crohn's disease...
and collagenous colitis to budesonide
Budesonide
Budesonide is a glucocorticoid steroid for the treatment of asthma and non-infectious rhinitis , and for treatment and prevention of nasal polyposis...
.