Inflammation

Inflammation is your body’s natural defense mechanism against injury, irritation, or infection. It is a process in which your immune system sends specialized cells, proteins, and chemical signals to an affected area to protect your body and aid in its healing. Although inflammation is usually beneficial and necessary, it can sometimes cause discomfort or harm if it persists for too long or occurs inappropriately.

Inflammation commonly occurs in response to:

• Infections caused by bacteria, viruses, or other microorganisms.

• Physical injury or trauma, such as cuts, burns, or surgery.

• Autoimmune conditions, where your immune system mistakenly attacks your body’s own healthy tissues.

• Irritation from chemicals or allergens.

• Chronic medical conditions such as arthritis or inflammatory bowel disease.

What are the signs and symptoms of inflammation?

The common signs and symptoms of inflammation include:

• Redness: Increased blood flow makes the affected area appear red.

• Swelling: Fluid accumulation causes the area to swell.

• Heat: Increased blood flow can cause the inflamed area to feel warm.

• Pain: Chemicals released during inflammation can cause discomfort or pain.

• Loss of function: Severe inflammation can temporarily impair the affected area’s ability to move or function properly.

Inflammation may also cause generalized symptoms, particularly if it is severe or widespread, including fever, fatigue, and a general sense of being unwell.

Types of inflammation

Doctors and pathologists generally describe inflammation in two main ways based on how quickly it starts and how long it lasts:

• Acute inflammation: This type of inflammation begins quickly, often within minutes or hours after an injury or infection. It typically lasts only a short period, ranging from a few days to a couple of weeks. Acute inflammation typically resolves once the injury has healed or the infection has cleared. Examples include the redness around a minor cut or swelling from a sprained ankle. However, in some instances, acute inflammation can persist for weeks or months, leading to tissue injury.

• Chronic inflammation: This type lasts much longer—weeks, months, or even years. Chronic inflammation can result from persistent injury, infection, or an ongoing immune response. Conditions like rheumatoid arthritis, asthma, inflammatory bowel disease, or persistent infections can cause chronic inflammation. Over time, chronic inflammation can lead to tissue damage or scarring.

What does inflammation look like under the microscope?

Pathologists diagnose inflammation by examining tissue samples under a microscope. Inflamed tissue typically contains increased numbers of immune cells, such as:

• Neutrophils: These cells are the first to appear during acute inflammation and play a crucial role in fighting infections, particularly bacterial infections.

• Lymphocytes and plasma cells: These cells are common in chronic inflammation, especially in response to viruses or ongoing immune reactions.

• Histiocytes and macrophages: Cells that help clear away damaged tissue and foreign materials. They are commonly seen in chronic inflammation.

• Eosinophils: Often appear in allergic reactions or parasitic infections.

The types and numbers of these immune cells help pathologists determine the cause, type, and severity of the inflammation.

Why is inflammation important in your pathology report?

Your pathology report may describe inflammation to help your doctor understand what’s causing your symptoms or condition. Identifying inflammation can confirm the presence of an infection, injury, autoimmune disorder, or chronic medical condition. By evaluating inflammation, your doctor can choose appropriate treatments such as antibiotics, anti-inflammatory medications, or other therapies tailored to your specific needs.

Knowing the type and extent of inflammation also helps your doctor monitor your response to treatment and determine whether additional medical care is necessary.