Ulcerative Colitis: Definition

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Ulcerative colitis is a long-term disease that causes inflammation and ulcers on the inner lining of the large intestine. It is a type of inflammatory bowel disease (IBD). Abnormal immune reactions cause the inflammation. The disease comes and goes, with flares and quiet periods.

A pathology report often doesn’t use the term ulcerative colitis. A pathologist usually describes the changes as chronic colitis, and your doctor makes the final diagnosis. This article explains what ulcerative colitis is, what the pathologist sees under the microscope, how doctors diagnose it, and what the wording on your report means.

What is ulcerative colitis?

Ulcerative colitis is a disease of the large intestine (colon). The inflammation damages the colon lining and causes ulcers. It usually involves the rectum most severely. From there, it spreads in a continuous stretch. The disease can range from mild to severe. It often alternates between flares and periods of remission.

The colon and rectum article describes these organs in more detail.

What are the symptoms of ulcerative colitis?

Ulcerative colitis symptoms vary from person to person. They include diarrhea, bloody stools, fever, weight loss, and bloating. Symptoms often get worse during a flare. Many other conditions cause similar symptoms, so doctors need tests to make the diagnosis.

What does ulcerative colitis look like under the microscope?

Under the microscope, ulcerative colitis shows signs of long-standing chronic inflammation and signs of current damage. The pathologist looks for these changes in biopsies of the colon:

Crypt distortion. The crypts are small pits in the lining of the colon. In long-standing disease, they become branched, shortened, or uneven. See crypt distortion.
Basal plasmacytosis. Extra plasma cells, a type of immune cell, collect at the bottom of the crypts. See basal lymphoplasmacytosis.
Cryptitis and crypt abscesses. Neutrophils, a type of white blood cell, invade the walls of the crypts. Doctors call this cryptitis. Clusters of neutrophils inside the crypts form crypt abscesses. Both indicate active disease.
Mucin loss. Goblet cells make mucus. In ulcerative colitis, they often contain less.
Paneth cell metaplasia. Cells that are normally found in the small intestine appear in the lower part of the colon. See Paneth cell metaplasia.
Ulcers. The lining is completely lost in some areas.

The pathologist also notes which changes are missing. Granulomas, which are small clusters of immune cells, are usually absent in ulcerative colitis. They occasionally occur.

Why do pathologists say chronic colitis?

Pathologists often write chronic colitis because ulcerative colitis and Crohn’s disease can look very similar under the microscope. The term covers both. Chronic means the changes are long-standing. If neutrophils are also present, the report may say chronic active colitis. See also chronic colitis.

Your doctor combines the biopsy result with the colonoscopy findings and your symptoms. This combination, not the biopsy alone, leads to the final diagnosis.

How is ulcerative colitis diagnosed?

If a doctor suspects ulcerative colitis, they perform a colonoscopy. During the procedure, the doctor uses a thin camera to look inside the colon. The doctor takes biopsies of the lining. The doctor often takes them along the entire length of the colon because the disease can affect some areas more than others. The article “Colonoscopy biopsy report” explains these reports.

What might my report say about ulcerative colitis?

Reports describe the changes in a few standard ways. Each laboratory phrases it a little differently:

Chronic colitis. The pathologist saw long-standing inflammation and changes in the crypts.
Chronic active colitis. The pathologist saw long-standing inflammation and neutrophils in the crypts.
Consistent with inflammatory bowel disease. The changes fit ulcerative colitis or Crohn’s disease. The pathologist cannot always distinguish between the two.
Negative for granulomas. The pathologist did not see granulomas.
Negative for dysplasia. The pathologist did not see dysplasia, which is a change in the cells that can lead to cancer.

Does ulcerative colitis increase the risk of cancer?

Ulcerative colitis increases the chance of colorectal cancer. The risk is higher when the disease affects more of the colon, is more severe, starts at a younger age, or lasts longer. For this reason, doctors recommend regular colonoscopies. Pathologists examine the biopsies for dysplasia. Your report will state whether they found it. See invasive adenocarcinoma of the colon for more information about this cancer.

What happens after ulcerative colitis is diagnosed?

The next steps depend on how severe the disease is and how much of the colon it involves. Your care team will explain your treatment options and a schedule for follow-up colonoscopies. The pathology report is one part of that plan.

Questions to ask your doctor

Does my biopsy show ulcerative colitis, Crohn’s disease, or chronic colitis?
Is the inflammation active?
How much of my colon does the disease affect?
Did the pathologist see dysplasia?
Were infections ruled out?
Do I need more biopsies or another colonoscopy?
How often will I need follow-up colonoscopies?
Which symptoms should lead me to call you?