Why is immunohistochemistry used in biopsy?

A biopsy removes a small tissue sample for examination. A pathologist may apply antibodies linked to visible markers to thin sections of that sample. If a target protein is present, the tissue shows a pattern that can be examined under a microscope. The pattern may help distinguish one tumour type from another, support the origin of cells, or identify features that influence treatment choices. It is interpreted alongside the tissue’s appearance, the biopsy site and other laboratory findings; one stain rarely answers every question by itself.

Results can be reported as a panel of markers rather than a single result. Some findings are descriptive, while others may guide a discussion about additional testing or therapy. Immunohistochemistry does not change the tissue and does not replace the pathologist’s overall diagnosis.

Ask whether the sample is being tested with a marker panel and when the pathology report is expected. Tell your care team if another hospital holds earlier biopsy material or pathology reports, because comparison can help interpretation. Keep the biopsy site instructions separate from questions about the laboratory test: protect the wound as advised and report increasing redness, drainage or pain. Do not interpret a pending stain as a diagnosis before the full report is reviewed.

Seek prompt medical advice for bleeding that does not settle with the instructed pressure, worsening swelling, fever, pus-like drainage, or severe pain at the biopsy site. Seek emergency help for heavy bleeding, breathing difficulty, fainting or sudden severe illness. These warning signs relate to the procedure and need attention regardless of when the immunohistochemistry result is due.

Ask which markers are being assessed, whether the result may change the diagnosis or treatment discussion, and whether more tissue or testing could be needed. Ask who will explain the final pathology report.