DE
Home Offer Syndromes Microscopic colitis

Understanding microscopic colitis: Causes, forms and symptoms

Microscopic colitis comprises the clinical pictures of lymphocytic colitis and collagenous colitis. Like Crohn's disease and ulcerative colitis, it belongs to the group of chronic inflammatory bowel diseases (IBD).

What is microscopic colitis?

Microscopic colitis is an inflammation of the colon mucosa (colitis). While inflammation in the bowel is normally visible during a colonoscopy in the form of redness or other signs of inflammation, this is not the case with microscopic colitis. In this case, the pathological changes can only be recognized under the microscope using tissue samples (biopsies), which explains the term "microscopic" colitis. As the disease is associated with chronic inflammation in the intestine, it is classified alongside Crohn's disease and ulcerative colitis as a chronic inflammatory bowel disease (IBD).

There are two different forms of microscopic colitis, collagenous colitis and lymphocytic colitis. Both clinical pictures have not been known for very long. Collagenous colitis was first described in 1976 and lymphocytic colitis in 1980. Although they are summarized under the generic term microscopic colitis, they show a different microscopic appearance (histological picture) in the tissue samples taken from the intestine. In collagenous colitis, a thickened connective tissue (collagen band) is noticeable in the intestinal mucosa. In lymphocytic colitis, an increased number of certain white blood cells, the lymphocytes, are found in the intestinal tissue. If the histological picture cannot be clearly assigned to one of the two forms of the disease, it is referred to as incomplete microscopic colitis.

The specific cause of microscopic colitis is still unknown. It is suspected that genetic factors interact with environmental factors to trigger the disease. Bacterial or viral infections and the use of certain medications may also play a role. It is also known that smoking is a risk factor for the development of microscopic colitis.

Epidemiology

In Europe, around 5 - 17 people per 100,000 inhabitants develop microscopic colitis every year, although regional variations are very pronounced. It is therefore a rare disease.

The actual figures are probably higher, as microscopic colitis is often misinterpreted as irritable bowel syndrome due to the similarity of the symptoms. It can therefore be assumed that the number of unreported cases is high.

Significantly more women than men suffer from microscopic colitis. It is not known how this gender distribution comes about. The disease often occurs in the second half of life.

Symptoms

The most important symptom of microscopic colitis is chronic, watery diarrhea, which is often accompanied by upper abdominal discomfort, nausea, flatulence, fatigue and more or less pronounced weight loss. It is also typical for diarrhea to occur during the night. Blood and mucus in the stool are unusual.

Due to the symptoms described, the disease can significantly impair the quality of life of those affected.

Concomitant diseases

Patients with microscopic colitis often suffer from concomitant diseases. These include, in particular, diseases outside the intestine such as rheumatic diseases, psoriasis, thyroid dysfunction, gluten intolerance (coeliac disease) and circulatory disorders.

How is microscopic colitis recognized?

The symptoms of microscopic colitis can resemble the symptoms of irritable bowel syndrome. For this reason, the diagnosis should not be made prematurely - even if a colonoscopy does not reveal any particular abnormalities. Rather, careful diagnostic clarification is crucial as the basis for effective treatment.

  • Medical history: A detailed medical history includes determining the patient's medical history and asking about the current symptoms, their duration and severity. During the doctor-patient consultation, it is also clarified whether food intolerances or allergies are known and whether family members may suffer from IBD or microscopic colitis.
  • Physical examination: The medical history is usually followed by a comprehensive physical examination, in which, for example, the abdomen is palpated or an ultrasound examination is carried out. Laboratory tests are also arranged.
  • Endoscopy: The most important examination for the detection of microscopic colitis is a colonoscopy. However, unlike other chronic inflammatory bowel diseases, the disease is not confirmed by endoscopic examination of the intestinal mucosa alone, as this usually appears unremarkable. To clarify the diagnosis, tissue samples are therefore taken from the entire large intestine at defined intervals (staged biopsy) from the intestinal mucosa and then examined under the microscope.

In the case of collagenous colitis a thickened collagen band becomes visible under the microscope when the pathologist examines the tissue samples using special staining methods. Collagen fibers are a specific protein structure that has a supporting function in the body. While the collagen band in the intestinal mucosa of healthy people is less than 5 micrometres (millionths of a metre) thick, it is at least 10 micrometres thick in collagenous colitis lymphocytic colitis on the other hand, the microscopic image shows an increased accumulation of special white blood cells (lymphocytes). Their number is four to five times higher than in healthy individuals.

How is microscopic colitis treated?

  • Drug therapy: If microscopic colitis is present, targeted treatment can be initiated. This aims to improve or, if possible, completely eliminate the symptoms and can thus improve the patient's quality of life in the long term. Very good therapeutic successes are achieved with budesonide, which belongs to the group of corticosteroids (also known as cortisone). Budesonide develops its anti-inflammatory effect specifically in the intestine and is subsequently broken down mainly in the liver. As a result, the active substance is highly effective and at the same time has fewer side effects than other corticosteroids. The active ingredient can be taken in various oral dosage forms. However, if the medication is discontinued after the symptoms have subsided, the majority of patients experience a relapse within a few months and thus a recurrence of the symptoms.
  • General measures: There is no special diet to follow in the case of microscopic colitis. What is important is a balanced, varied diet, as generally recommended by nutrition experts. It should also be clarified whether there is a gluten intolerance (coeliac disease) in addition to microscopic colitis, as this often occurs in combination with microscopic colitis. It is known that smoking has a negative effect on the course of the disease. Patients diagnosed with microscopic colitis should therefore stop smoking.

What is the course and prognosis of microscopic colitis?

Microscopic colitis is not a life-threatening disease and its course is generally benign. However, if left untreated, almost every second patient suffers from chronic or recurrent diarrhea, which can have a massive impact on quality of life.

According to current knowledge, there is no increased risk of developing bowel cancer with microscopic colitis.