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Dr. Robert D. Fusco, Medical Director    
Collagenous Colitis (Microscopic Colitis, Lymphocytic Colitis)


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In medicine, the suffix "-itis" refers to inflammation as in tonsilitis or appendicitis. You may have also heard of the word colitis. It refers to inflammation of the colon, or large intestine. When the word colitis is used in medicine, most doctors think of two common so-called "inflammatory bowel diseases (IBD)" - ulcerative colitis or Crohn's disease.

But, there is a third type of colitis that is less well known - usually termed collagenous colitis. First identified in Sweden in 1976, collagenous colitis is also referred to as lymphocytic colitis which reflects a variation of the same disease. Because of the similarities of these two disorders, they are commonly considered a single category for the purposes of treatment and referred to as microscopic colitis.

Who gets collagenous colitis?
Collagenous colitis is most commonly seen in middle-aged women with chronic, watery diarrhea. Men and children are also affected, but less often. Most patients are Caucasians living in industrialized countries such as Northern Europe, Canada, the United States, Australia and New Zealand. The incidence is estimated to be about 2 cases per 100,000 population. It does not appear to be contagious, but is sometimes hereditary. Often symptoms have been present for several years before an accurate diagnosis is made. There can be an association with other auto-immune disorders, such as thyroid disorders, diabetes and rheumatoid arthritis.

What are the symptoms?
Most patients with collagenous colitis complain of intermittent attacks of diarrhea and crampy abdominal pain, often with multiple loose watery bowel movements per day. In severe cases, this can lead to weakness and dehydration. These episodes may come on suddenly without any obvious explanation.

What causes collagenous colitis?
The cause of collagenous colitis is unknown. Several unproven theories exist including damage from food poisoning, an auto immune disorder, or an association with antiinflammatory drugs such as ibuprofen. About half of the patients can identify a specific time when the first episode occurred.

How is collagenous colitis diagnosed?
When a patient is being evaluated for persistent diarrhea, there is a long list of possible causes. The doctor orders a series of diagnotic tests to narrow the possibilities. These will involve a history and physical examination and laboratory analysis of blood and stool samples. Such routine laboratory data is most often normal.

Evaluation with a "scope test" such as colonoscopy or sigmoidoscopy is often one of the major diagnostic tests performed. Traditional IBD such as ulcerative colitis and Crohn's disease can often be diagnosed by knowing the patient's symptoms and the appearance of the colon lining during colonoscopy. However, the inflammatory changes of collagenous colitis are more subtle and cannot be seen with the naked eye. During a scope exam, the colon looks normal. To diagnose collagenous colitis, biopsies must be taken and examined under the microscope - hence the name, microscopic colitis. Without a biopsy, collagenous colitis is frequently misdiagnosed as irritable bowel syndrome (IBS).

In collagenous colitis, the diagnosis rests with the pathologist - a physician specially trained to examine biopsies. The wall of the colon is made up of 5 circular layers. The innermost is called the mucosa. In collagenous colitis, the biopsy reveals thickening of the layer beneath the mucosa due to the deposition of excessive collagen (a major protein in connective tissue, cartilage, and bone). There is also significant infiltration of the overlying surface mucosa by underlying white blood cells called lymphocytes. Lymphocytic colitis differs only in lacking the thickened collagenous plate.

What treatment is available?
No cure is yet available. Treatment is directed at reducing inflammation and the symptoms of diarrhea. This usually involves a "trial and error" process as each case is different. With treatment, most symptoms can be controlled. However, when treatment is tapered, the symptoms usually reappear. Most patients, therefore, need continual therapy to control symptoms.

There is no specific diet to follow. Foods containing caffeine or lactose should be excluded from the diet, since they stimulate fluid secretion in the colon. If a patient is unable to digest fats, a low-fat diet may be helpful. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen should be avoided, since studies have suggested that they may be associated with collagenous colitis. Tylenol (acetaminophen) is permissible.

The first line of medical treatment is usually Azulfidine (sulfasalizine) or Asacol (mesalamine) which are anti-inflammatory agents that reduce inflammation within the inner lining of the colon. These drugs are also used to treat other forms of IBD and are safe for long term use. In severe cases, a short trial of a steroid drug like Prednisone may be used to reduce symptoms. But side effects usually limit long term use. A newer form of steroid called Entocort has been helpful with fewer side effects. Entocort remains mostly in the intestinal tract and is not absorbed as much into the bloodstream so systemic side effects are less common. It was developed for patients with Crohn's colitis, but has been shown to be helpful in some patients with collagenous colitis.

High dose Pepto-bismol is sometimes tried as an alternative agent usually given as 8 chewable tablets daily for 8 weeks. Research done at Baylor Medical Center in Dallas, suggests this can be quite effective in some patients.

To treat diarrhea, drugs such as Lomotil (diphenoxylate) and Imodium (loperamide) are often prescribed. Paradoxically, some patients respond to fiber supplements such as Metamucil (psyllium) or Citrucel (methylcellulose). These agents are usually recommended for treatment of constipation when they are taken with large amounts of water. However, when taken with small amounts of water, these agents can absorb excess fluid within the colon and help to firm up loose stools.

One unusual agent that works quite well in many individuals is cholestryramine. Most often prescribed to treat high blood cholesterol, this medication can also be used to limit diarrhea in cases of collagenous colitis. Cholestryamine comes in the form of a powder that is mixed with water. Usually, a low dose of 1/2 to 1 packet a day works well to stop episodes of watery diarrhea, especially those that occur after meals. Cholestryamine is safe for long term use - having only two minor side effects. With higher doses, it can cause constipation. This is simply treated by reducing the daily dose. Also, if taken at the same time, cholestryramine can reduce the absorption of other drugs. It should not be taken within 3 hours of any other important medication. Of course, this treatment can have the secondary benefit of reducing cholesterol.

Antibiotic therapy is often tried with drugs such as Flagyl (metronidazole), erythromycin and penicillin. The response varies, but the results generally are not long lasting. Most responders relapse shortly after the course of antibiotics is completed.

Probiotics
There are as yet no controlled scientific studies, but some patients have reported a reduction in diarrhea after adding a probiotic supplement to their regimen. Probiotics are "healthy" bacteria that help restore the balance of bacteria within the colon. Yogurt is one simple source of acidophyllus, a healthy bacteria. More effective compounds are available as Culturelle and Florastor.

Surgery
Radical surgery to remove the colon and create a diverting ileostomy is a potential cure, but is reserved for severe cases of intractable diarrhea that fail to respond to all other measures. It is seldom recommended.

Prognosis
Collagenous colitis is a real entity with objective(microscopic) criteria to diagnose it, and a variety of medical treatments are available. However, whenever an illness has multiple treatment options, it generally means that no one best treatment exists. This is the case with collagenous colitis. After 25 years, it is still poorly understood and a cure is not yet available. With continued treatment, symptoms can usually be reduced, although repeat biopsies do not usually return completely to normal.

Unlike ulcerative colitis and Crohn's disease, collagenous colitis most often follows a chronic benign course. The experience with this disease is limited but studies suggest there is no increased risk for complications or colorectal cancer in this group of patients.

The long term outlook for patients with collagenous colitis varies. Although it is not progressive nor fatal, it can be disabling. Unfortunately, it is not yet possible to predict who will do well and who will not. Some individuals quickly respond to treatment and the symptoms never return. Most have a waxing and waning course where the symptoms come and go despite treatment. This can be quite frustrating for both the patient and doctor. Patients who do the best are those that keep an optimistic attitude, work with their doctor to determine the best treatment plan, and try not to allow collagenous colitis to interfere with their enjoyment of life.

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