April 29, 2026
An abscess is a localized collection of pus — a thick fluid made up of dead cells, debris, and immune cells — that builds up inside body tissue. It forms when the body’s immune system mounts a strong response to an injury, infection, or other source of irritation, and the responding cells accumulate faster than they can be cleared away. An abscess is not a type of cancer, but it can sometimes be found alongside other conditions in a pathology sample. Finding an abscess in your report tells your doctor that the immune system was actively reacting to something in the tissue at the time the sample was taken.
What causes an abscess?
Abscesses can form for several different reasons. While infection is one common cause, not all abscesses are infectious:
- Infection — bacteria are the most frequent cause. An abscess may develop when bacteria enter tissue through a wound, a blocked gland or duct, or spread from a nearby infection. Fungi can also cause abscesses, though less commonly.
- Trauma — physical injury can trigger an immune response that leads to abscess formation even without infection.
- Obstruction — when a gland, duct, or hollow structure becomes blocked, fluid and immune cells can accumulate and form an abscess.
- Chronic inflammatory conditions — conditions such as Crohn’s disease can cause repeated episodes of inflammation that lead to abscess formation.
- Tumors — an abscess can sometimes develop in tissue near a tumor, if the immune system reacts to tumor material in the surrounding area.
What does an abscess look like under the microscope?
When a pathologist examines tissue containing an abscess under the microscope, the most prominent finding is a dense collection of neutrophils — a type of white blood cell that rushes to sites of infection or injury and helps break down harmful material. These neutrophils are typically surrounded by dead tissue and cellular debris. Depending on the cause, other immune cells such as macrophages or lymphocytes may also be present. In some cases, bacteria or fungi can be seen directly in the tissue, which helps identify the cause of the abscess.
What does finding an abscess in my report mean?
An abscess in a pathology report means that the immune system was responding to something abnormal in the tissue at the time the sample was taken. The finding itself is a description of what was seen — your pathologist will also look for clues about the underlying cause, such as signs of infection, a blocked structure, or an associated condition like inflammation.
The significance of an abscess depends entirely on its cause and location. Some abscesses are straightforward to treat with antibiotics or drainage. Others may point to an underlying condition — such as Crohn’s disease, a blocked salivary gland, or a perforated organ — that requires further investigation or management. Your doctor will use the pathology findings together with your clinical history to determine the most appropriate next steps.
Questions to ask your doctor
- What caused the abscess found in my sample?
- Is there an underlying condition — such as an infection or inflammatory disease — that needs to be treated?
- Will I need antibiotics, drainage, or any other treatment?
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