What is immunohistochemistry used for?

A laboratory applies selected antibodies to thin slices of tissue, often from a biopsy. If a target protein is present, the antibody binds to it and produces a colour or other visible signal under a microscope. A pathologist studies the pattern and location of these signals alongside the tissue's appearance.

The findings can help distinguish one tumour type from another, indicate where abnormal cells began, and reveal markers that may affect treatment selection. The test is interpreted with the biopsy report, scans, examination findings, and medical history; a stain is one part of the diagnostic picture.

Ask which tissue sample will be tested, what the laboratory is looking for, and when the report is expected. Usually, immunohistochemistry is performed on tissue already collected, so it may not require a separate procedure. Tell the clinical team about previous biopsy results or treatment that could affect interpretation, and ask whether additional stains or tests may be needed.

Immunohistochemistry itself does not usually cause new symptoms because it is a laboratory analysis. Contact the team promptly for worsening pain, bleeding, fever, redness, swelling, or drainage after the biopsy that supplied the tissue. Seek urgent help for heavy bleeding, severe breathing difficulty, fainting, or rapidly worsening illness.

Which proteins or markers are being examined? How could the result change the diagnosis or treatment discussion? Does the report need comparison with an earlier sample? When will the findings be explained, and who should I contact if the result is unclear?