What should you know about ISH immunohistochemistry?

Immunohistochemistry uses antibodies that attach to selected proteins in cells, creating a stain that a laboratory specialist interprets. ISH, or in-situ hybridisation, uses labelled probes to look for a particular DNA or RNA sequence within the tissue. Some reports discuss both methods because a protein result and a gene-related result can answer different questions.

The result may be reported as detected, not detected, weak or strong, or with a pattern that needs specialist interpretation. A positive marker does not by itself describe the whole cancer, its stage, or the treatment that will work. The meaning depends on the tumour type, the quality of the sample, other pathology findings, and your clinical assessment.

Ask which marker was tested, whether the sample was adequate, and whether the finding is considered definite or needs confirmation. Request an explanation of how the result affects diagnosis, staging, or treatment choices. Results can sometimes be reviewed or repeated on another tissue section when the staining is unclear or the clinical picture does not fit.

Keep the full pathology report rather than relying on a single word such as positive. A [Biopsy](/treatments/diagnostics-and-staging/biopsy/) provides the tissue that these laboratory methods examine, while [Immunohistochemistry](/technology/immunohistochemistry/) explains the wider technology.

The laboratory test itself does not usually create an emergency. Contact your clinical team promptly if you have not received an expected result, do not understand a finding that changes your treatment appointment, or develop new symptoms after a biopsy such as heavy bleeding, worsening swelling, fever, or severe pain. Seek emergency help for difficulty breathing, collapse, or uncontrolled bleeding.

Which protein, gene, or RNA signal was tested? What does the result mean for my specific tumour? Was the sample sufficient, and is another test needed? Could the result alter treatment or only add diagnostic detail? Who will explain the complete pathology report, and when should I expect that discussion?