Ulcer: Definition

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An ulcer is an injury in which the surface cells of a tissue are lost. The loss exposes the tissue underneath. Ulcers most often occur on the skin, in the stomach, and in the mouth. They can occur almost anywhere in the body.

An ulcer is a finding, not a diagnosis. It describes what the pathologist saw under the microscope. The cause of the ulcer is a separate question. This article explains what an ulcer is, how it differs from an erosion, what causes ulcers, and what the wording on your report means.

What is an ulcer?

An ulcer is a break in the lining of a tissue. The lining of most organs is a layer of cells called the epithelium. In an ulcer, the epithelium is completely gone in one area. The connective tissue underneath is exposed to the surface. The open area often looks like a crater.

How is an ulcer different from an erosion?

An ulcer is deeper than an erosion. An erosion removes only the epithelium. It does not reach the submucosa or the tissue under the skin. Erosions usually heal with little or no scarring. An ulcer goes deeper, so it heals more slowly and can leave a scar.

Where do ulcers occur?

Ulcers can form wherever a surface lining exists. The most common sites are:

Stomach and duodenum. A peptic ulcer is a sore on the lining of the stomach or the duodenum, the first part of the small intestine.
Skin. Skin ulcers include venous ulcers, which form when the valves in the veins of the leg do not work properly. They also include diabetic foot ulcers and pressure ulcers, which are also called bedsores. See the skin article.
Mouth. A canker sore is a common ulcer in the mouth.
Bowel. Ulcers in the colon may signal inflammatory bowel disease. See colon and rectum.
Other sites. Ulcers can also develop on the cornea of the eye and in the genital area.

What causes an ulcer?

Any process that damages surface cells and slows healing can cause an ulcer. Common causes include:

Injury. Trauma, friction, or long-term pressure can break down the surface.
Infection. Helicobacter pylori (H. pylori) is a bacterium that infects the stomach. It is one of the two most common causes of peptic ulcers.
Medicines. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the other common cause of peptic ulcers. They include aspirin, ibuprofen, and naproxen. Your doctor decides whether to change a medicine.
Chronic inflammation. Long-term chronic inflammation can wear down the lining. Crohn’s disease and ulcerative colitis can cause ulcers in the bowel.
Vein problems. Faulty valves in the leg veins are thought to cause venous ulcers.
Radiation. Radiation therapy can damage surface cells.
A tumor. A large tumor can break through the surface and form an ulcer. This is more likely when the tumor cells invade the lining.

What does an ulcer look like under the microscope?

Under the microscope, an ulcer shows a complete loss of the surface epithelium. Older ulcers often show several layers:

Surface. A layer of fibrinopurulent exudate covers the crater. It contains fibrin (a clotting protein) and neutrophils. It may also contain dead tissue and blood.
Base. Granulation tissue lies under the surface. It is new tissue rich in small blood vessels. It also contains inflammatory cells, such as lymphocytes and histiocytes.
Deep layer. In long-standing ulcers, a scar of fibrous tissue lies in the deepest layer.

The tissue next to the ulcer often shows inflammation too. In the stomach, doctors call this gastritis. Granulation tissue also signals healing. It appears as the ulcer begins to mend.

How is an ulcer identified?

A pathologist identifies an ulcer by examining a biopsy under a microscope. The pathologist looks for the missing surface lining and the changes in the tissue below. The pathologist also looks for a cause. In the stomach, for example, the pathologist looks for H. pylori. The pathologist also checks the sample for tumor cells because some cancers form ulcers.

What might my report say about an ulcer?

Reports describe an ulcer in a few standard ways. Each laboratory phrases it a little differently:

Ulcer or ulceration. The surface lining is completely missing.
Ulcer with granulation tissue. The ulcer is healing, or has been present for some time.
Erosion. Only the surface lining is missing. This is a milder change than an ulcer.
A named cause. The report may name a likely cause, such as H. pylori or inflammatory bowel disease.
No malignancy identified. The pathologist did not see tumor cells. The pathologist checks only the tissue in the sample, so this result lowers the concern but cannot rule out cancer.

Is an ulcer cancer?

An ulcer is not cancer. It is a loss of surface lining. However, some cancers form an ulcer as they grow. For this reason, doctors and pathologists check ulcers for tumor cells. Your report will state whether the pathologist found tumor cells.

What happens after an ulcer is identified?

Next steps depend on the cause and location. Doctors treat the cause so the ulcer can heal. Some ulcers bleed, so your doctor may ask you to watch for signs of bleeding. Your doctor may repeat the biopsy to check that the ulcer has healed. Your doctor can explain the plan for your ulcer.

Questions to ask your doctor

What caused my ulcer?
Did the pathologist look for H. pylori or another infection?
Did the pathologist see any tumor cells?
Is this an ulcer or an erosion?
Could a medicine I take be the cause?
Does my report show signs of long-term inflammation?
Do I need a repeat biopsy to check that the ulcer has healed?
Which symptoms should lead me to call you?