Immunohistochemistry

Immunohistochemistry uses antibodies and coloured markers to show selected proteins in cells from a tissue sample. In a laboratory, thin sections of preserved tissue are placed on slides. Antibodies bind to matching targets, and a chemical reaction makes those sites visible under a microscope. The pattern and strength of staining can help a pathologist classify a tumour, distinguish similar-looking conditions, or identify features relevant to treatment planning.

Immunohistochemistry is performed on tissue obtained during a biopsy or operation. The pathologist chooses a panel of stains based on the appearance of the cells and the clinical question. Results may support tumour classification, indicate whether cells carry a particular marker, or help match a patient with a treatment that depends on that marker. The findings are interpreted with the microscope appearance, imaging, symptoms, and other laboratory information.

A stain is one part of a pathology assessment. A weak, absent, or unexpected signal can reflect true biology, limited tissue, handling, or technical variation. Some markers are shared by more than one tumour type, so a single stain rarely settles every diagnostic question. The pathologist may recommend additional stains, molecular testing, review of another sample, or correlation with imaging and clinical findings. A marker result does not by itself predict exactly how an individual will respond.

Routine microscopy examines cell shape and tissue arrangement without targeted staining. Special stains highlight substances such as mucus or minerals. Molecular tests look for selected genetic changes, while flow cytometry analyses markers on individual cells in suitable fresh samples. These methods can complement immunohistochemistry or answer a different question. The laboratory selects tests according to the tissue available and the diagnostic problem.

You usually do not feel immunohistochemistry itself because it happens in the laboratory after tissue collection. Your report may list the marker tested, whether staining is present, and how the pathologist interpreted the pattern. Ask which diagnosis the stains support, whether more testing is needed, and how the result affects the next treatment discussion. Your clinician can explain unfamiliar terms in the context of the complete report.

The laboratory staining procedure does not add a procedure to your body. Any discomfort, bleeding, infection risk, or wound care relates to obtaining the tissue through a biopsy or operation. Follow the instructions for the sampling site and report increasing redness, drainage, fever, or worsening pain. Laboratory results can take time when several stains or expert reviews are required.