Collagenous Colitis (Microscopic Colitis, Lymphocytic Colitis)
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
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
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
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.
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.
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.
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.