What should you know about IHC immunohistochemistry?

A pathologist prepares very thin sections from tissue, often from a [Biopsy](/treatments/diagnostics-and-staging/biopsy/). Antibodies are added to the sections. Each antibody is designed to bind to a particular protein or marker. A chemical or coloured signal makes the bound areas visible under a microscope.

The pattern and strength of staining can support the identification of a tumour type, distinguish similar-looking conditions, or show whether a marker is present for treatment planning. IHC does not examine every feature of a tumour and does not replace the pathologist's assessment of the tissue, scans, and clinical history. Results can be reported as positive, negative, weak, strong, or indeterminate, depending on the marker.

Ask which markers were tested and why. Request an explanation of any terms such as staining pattern, control, or indeterminate result. If the sample is limited, your team may prioritise tests or discuss whether another tissue sample is appropriate.

Keep the report with your medical records and ask how it changes the next step. The detailed [Immunohistochemistry](/technology/immunohistochemistry/) result may be combined with other pathology methods, imaging, or molecular testing before a diagnosis and treatment plan are finalised.

The staining test itself does not usually cause symptoms because it is performed in a laboratory on tissue already collected. If you recently had a biopsy, contact your care team for increasing redness, swelling, drainage, fever, or pain at the procedure site. Seek urgent help for heavy bleeding, fainting, severe breathlessness, or rapidly worsening pain.

What was the purpose of each marker tested? Does the result support one diagnosis more than another? Is more tissue or another test needed, and when will the pathology findings be reviewed with me?