Non-reactive

In a pathology report, the term non-reactive is used to describe the result of a laboratory test called immunohistochemistry. This test helps pathologists identify specific proteins or other substances made by cells in a tissue sample. When a group of cells is described as non-reactive, it means the cells did not produce the protein or substance that the test was designed to detect.

Another word for non-reactive is negative. The opposite of non-reactive is reactive or positive, which means the protein was present and detected in the cells.

What is immunohistochemistry?

Immunohistochemistry (IHC) is a special test that allows pathologists to identify specific proteins in tissue samples using antibodies that bind to those proteins. These antibodies are linked to dyes that can be seen under the microscope, allowing the pathologist to see which cells are producing the protein and where the protein is located within the cells or tissue.

Immunohistochemistry is often used to:

• Help diagnose different types of tumors.

• Determine whether a tumor is benign or malignant.

• Identify the origin of cancer (for example, whether it started in the lung, colon, or breast).

• Guide treatment by testing for hormone receptors or predictive markers (such as HER2 or PD-L1).

What does a non-reactive result mean?

A non-reactive result means that no signal was seen in the cells tested. In other words, the cells did not produce the protein or marker that the test was looking for.

For example:

• If a breast tumor is tested for estrogen receptor (ER) and the result is non-reactive, it means the tumor cells are not producing estrogen receptor protein.

• If a tumor is tested for CD20 to determine if it is a B-cell lymphoma and the result is non-reactive, it means the tumor cells do not have features of B cells.

This information helps the pathologist narrow down the diagnosis and guide the medical team in choosing the most effective treatment.

Does non-reactive always mean the same thing?

Not necessarily. A non-reactive result must be interpreted in context. The meaning of a non-reactive result depends on:

• What protein was being tested.

• What type of tissue or tumor is present.

• Why the test was ordered.

In some cases, a non-reactive result rules out a specific diagnosis. In other cases, it helps support a different diagnosis. Sometimes, a tumor may show a mix of reactive and non-reactive areas, which may also have diagnostic or prognostic significance.

Is non-reactive the same as normal?

No. Non-reactive does not mean normal or healthy. It simply means that a specific protein was not detected in the sample tested. In some situations, non-reactive results may be found in both normal tissue and cancer. In others, the absence of a protein may indicate a disease process, such as cancer, infection, or a degenerative condition.

What is the difference between non-reactive and reactive?

• Non-reactive (negative) – The cells did not produce the protein or marker being tested.

• Reactive (positive) – The cells did produce the protein or marker being tested.

Depending on the test, a reactive result may suggest a specific cell type, tumor origin, or treatment target, while a non-reactive result may help exclude certain diagnoses or indicate that a specific treatment may not be effective.

Questions to ask your doctor

• What was the immunohistochemistry test looking for?

• What does the non-reactive result mean for my diagnosis?

• Are additional tests needed to confirm the diagnosis?

• Will this result affect my treatment options or prognosis?

• Were any other markers reactive or positive?