🧪 General Principles🟡 High-yieldLaboratory Techniques

Special Stains and Immunohistochemistry

Laboratory methods that colour specific tissue components or use antibodies to reveal particular molecules, helping a pathologist identify and classify disease.

Key points

The routine stain is haematoxylin and eosin (H and E): haematoxylin stains nuclei blue-purple and eosin stains the cytoplasm and connective tissue pink.
Special stains highlight particular substances, such as Periodic acid-Schiff (PAS) for carbohydrates and glycogen, and Perls Prussian blue for iron.
Ziehl-Neelsen stain shows acid-fast bacteria such as the tuberculosis organism in red, while the Gram stain separates bacteria into Gram-positive (purple) and Gram-negative (pink) groups.
Congo red stains amyloid, which then shows a characteristic apple-green colour under polarised light.
Immunohistochemistry uses antibodies linked to an enzyme-and-chromogen or a fluorescent label to detect specific proteins in tissue, which helps to pinpoint a tumour's cell of origin.
For example, cytokeratins mark epithelial (carcinoma) cells, and a panel of markers helps decide where a secondary tumour of unknown origin came from.

Memory trick

H and E for the overview, then targeted stains: PAS for sugars, Perls for iron, Ziehl-Neelsen for TB, Congo red for amyloid, and antibodies (IHC) for proteins.

All of Pathology More General Principles

Next in Pathology · General Principles

Loading…

🧪 General Principles🟡 High-yieldLaboratory Techniques

Special Stains and Immunohistochemistry

Laboratory methods that colour specific tissue components or use antibodies to reveal particular molecules, helping a pathologist identify and classify disease.

Key points

The routine stain is haematoxylin and eosin (H and E): haematoxylin stains nuclei blue-purple and eosin stains the cytoplasm and connective tissue pink.
Special stains highlight particular substances, such as Periodic acid-Schiff (PAS) for carbohydrates and glycogen, and Perls Prussian blue for iron.
Ziehl-Neelsen stain shows acid-fast bacteria such as the tuberculosis organism in red, while the Gram stain separates bacteria into Gram-positive (purple) and Gram-negative (pink) groups.
Congo red stains amyloid, which then shows a characteristic apple-green colour under polarised light.
Immunohistochemistry uses antibodies linked to an enzyme-and-chromogen or a fluorescent label to detect specific proteins in tissue, which helps to pinpoint a tumour's cell of origin.
For example, cytokeratins mark epithelial (carcinoma) cells, and a panel of markers helps decide where a secondary tumour of unknown origin came from.

Memory trick

H and E for the overview, then targeted stains: PAS for sugars, Perls for iron, Ziehl-Neelsen for TB, Congo red for amyloid, and antibodies (IHC) for proteins.

All of Pathology More General Principles