What should you know about staining immunohistochemistry?

A pathologist applies selected antibodies to thin sections of tissue. When an antibody attaches to its target protein, a chemical marker creates a colour or other visible signal. The pattern, location and strength of staining are considered alongside the tissue's shape and other laboratory findings. A positive or negative stain is not a diagnosis by itself; its meaning depends on the marker, the sample and the clinical question.

STAT6, hormone receptors and other markers answer different questions. Some help classify a tumour, while others can support a distinction between conditions that look alike under a microscope. The report may describe staining as present, absent, weak, strong, focal or diffuse.

Ask which protein was tested, why that marker was chosen and whether the result changes the diagnosis or treatment discussion. Request an explanation of terms such as equivocal, focal or non-specific, and ask whether additional stains, a review of the biopsy or molecular testing is needed. Keep the pathology report with your imaging and clinic letters so the treating team can interpret the result in context.

Contact the clinic promptly if you do not understand whether the report is final, if a result conflicts with the explanation you received, or if a planned appointment has not been arranged after a biopsy. Seek urgent medical help for severe bleeding, breathing difficulty, fainting or rapidly worsening illness after a procedure; staining itself is performed on tissue in the laboratory and does not cause those symptoms.

Which marker was stained, what does its pattern mean for my tissue, and could another test change the interpretation?