Metaplasia

Metaplasia describes a process in which one type of normal tissue in your body is replaced by a different kind of normal tissue not usually found in that location. This change typically occurs because the tissue responds to ongoing stress, irritation, or injury. Metaplasia can happen in many parts of the body, including the esophagus, stomach, bladder, breast, ovaries, and lining of the uterus (endometrium).

What causes metaplasia?

Metaplasia usually develops as your body tries to protect itself from chronic irritation, inflammation, repeated injury, or ongoing infection. The specific cause depends on the affected area. For example, long-term acid reflux can lead to metaplasia in the esophagus, while chronic bladder infections or irritation may cause metaplasia in the bladder. Metaplasia represents your body’s attempt to adapt and become more resistant to ongoing stress or injury.

Does metaplasia mean cancer?

Metaplasia itself is not cancer. Instead, it is a benign (non-cancerous) change involving normal types of cells, although these cells are found in an abnormal location. However, the presence of metaplasia can sometimes indicate an increased risk of developing cancer in the future, especially if the underlying cause (such as chronic irritation or inflammation) continues.

Does metaplasia increase your risk of developing cancer?

Some types of metaplasia can increase your risk of developing cancer over time, particularly if the underlying cause persists. For example, intestinal metaplasia in the esophagus (often called Barrett’s esophagus) increases the risk of developing a type of cancer called esophageal adenocarcinoma. Similarly, intestinal metaplasia in the stomach is associated with a higher risk of stomach cancer. However, not all types of metaplasia carry the same risk, and your doctor will help determine your risk based on the type of metaplasia and the location in your body.

What is the difference between metaplasia and dysplasia?

Metaplasia involves one normal type of tissue changing into another normal tissue type, and it is usually reversible if the cause is removed or treated. In contrast, dysplasia describes an abnormal change in the appearance, size, and organization of cells. Dysplasia is considered precancerous because the abnormal cells have the potential to turn into cancer if left untreated. While metaplasia can sometimes progress to dysplasia, they are distinct processes, with dysplasia representing a more serious concern.

How is this diagnosis made?

Metaplasia is usually diagnosed when a biopsy (tissue sample) is taken from the affected area and examined under a microscope by a pathologist. Your pathologist looks for cells that appear normal but belong to a tissue type different from that expected in that location. Sometimes, additional special stains or immunohistochemistry tests are performed to confirm the type of cells and clarify the diagnosis.

What are some common examples of metaplasia, and where do they occur?

Some common examples of metaplasia include:

• Intestinal metaplasia: This type of metaplasia is often seen in the esophagus (Barrett’s esophagus) due to chronic acid reflux, and in the stomach from ongoing inflammation (chronic gastritis).

• Squamous metaplasia: This type of metaplasia frequently occurs in the airways of smokers due to irritation from smoke or in the bladder due to chronic infections or irritation.

• Apocrine metaplasia: Apocrine metaplasia is commonly seen in breast tissue as a non-cancerous change.

• Foveolar metaplasia: Foveolar metaplasia is usually found in the stomach or duodenum, often related to chronic irritation or inflammation.

• Pancreatic metaplasia: This type typically occurs in the stomach or small intestine, often as a reaction to ongoing inflammation.

• Tubal metaplasia: Tubular metaplasia usually involves the cervix or endometrial lining and occurs due to chronic hormonal or inflammatory stimuli.

What does metaplasia look like under the microscope?

Under the microscope, metaplasia appears as normal, healthy-looking cells arranged neatly in layers or patterns, but these cells are not normally found in the examined location. For instance, intestinal metaplasia in the esophagus looks like normal intestinal cells (including goblet cells) rather than typical esophageal cells. Pathologists carefully evaluate the cell type, pattern, and organization to confirm the diagnosis and exclude more serious conditions such as dysplasia or cancer.