Special stains

Special stains

A ‘special stain’ is a stain that is not routine, i.e. not an H&E stain. Immunohistochemical stains are conventionally separate from this category . Some special stains demonstrate normal substances in increased quantities or in abnormal locations. The periodic acid–Schi ff (PAS) stain demonstrates both - glycogen and mucin, whereas a diastase PAS (D-PAS) stain demonstrates mucin, e.g. in an adenocarcinoma. Perls Prussian blue stain demonstrates iron accumulation ( Figure 11.23 ), e.g. in haemochromatosis. A reticulin stain helps to demonstrate fibrosis ( Figure 11.24 ). Elastic stains also show fibrosis and can highlight blood vessels by outlining their elastic laminae. Special stains can also re veal the accumulation of abnormal substances, e.g . a Congo red stain for amyloid. Summary box 11.9 Additional techniques for assessing tissue /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF Summary box 11.10 Common special stains /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF

Special stains Immunohistochemistry Electron microscopy In situ hybridisation, including /f_l uorescence in situ hybridisation (FISH) Molecular pathology techniques (including single biomarker polymerase chain reaction [PCR] and next-generation sequencing [NGS]) PAS: glycogen, fungi D-PAS: mucin Perls Prussian blue: iron Reticulin: reticulin /f_i bres, /f_i brosis van Gieson: collagen Congo red: amyloid Ziehl–Neelsen: mycobacteria

Special stains are also useful for the diagnosis of infection. Some microorganisms are not visible on routine H&E slides but are demonstrable with a stain. For example, a Ziehl–Neelsen stain demonstrates acid-fast bacilli, particularly mycobacteria, by staining them bright red on a blue background ( Figure 11.20 Other microorganisms may be detectable on H&E but are easier to see with a special stain, e.g. fungi (PAS or Grocott stain), protozoa (Giemsa stain) and spirochaetes (Warthin– in situ hybridisation Starry stain). Immunohistochemistry and also help to detect some microorganisms (see Immunohisto chemistry: infections and other applications and hybridisation ).

(b) Figure 11.23 (a) Brown pigment in a biopsy. (b) A Perls stain is posi tive, indicating that the pigment is iron.

Special stains

A ‘special stain’ is a stain that is not routine, i.e. not an H&E stain. Immunohistochemical stains are conventionally separate from this category . Some special stains demonstrate normal substances in increased quantities or in abnormal locations. The periodic acid–Schi ff (PAS) stain demonstrates both - glycogen and mucin, whereas a diastase PAS (D-PAS) stain demonstrates mucin, e.g. in an adenocarcinoma. Perls Prussian blue stain demonstrates iron accumulation ( Figure 11.23 ), e.g. in haemochromatosis. A reticulin stain helps to demonstrate fibrosis ( Figure 11.24 ). Elastic stains also show fibrosis and can highlight blood vessels by outlining their elastic laminae. Special stains can also re veal the accumulation of abnormal substances, e.g . a Congo red stain for amyloid. Summary box 11.9 Additional techniques for assessing tissue /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF Summary box 11.10 Common special stains /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF

Special stains Immunohistochemistry Electron microscopy In situ hybridisation, including /f_l uorescence in situ hybridisation (FISH) Molecular pathology techniques (including single biomarker polymerase chain reaction [PCR] and next-generation sequencing [NGS]) PAS: glycogen, fungi D-PAS: mucin Perls Prussian blue: iron Reticulin: reticulin /f_i bres, /f_i brosis van Gieson: collagen Congo red: amyloid Ziehl–Neelsen: mycobacteria

Special stains are also useful for the diagnosis of infection. Some microorganisms are not visible on routine H&E slides but are demonstrable with a stain. For example, a Ziehl–Neelsen stain demonstrates acid-fast bacilli, particularly mycobacteria, by staining them bright red on a blue background ( Figure 11.20 Other microorganisms may be detectable on H&E but are easier to see with a special stain, e.g. fungi (PAS or Grocott stain), protozoa (Giemsa stain) and spirochaetes (Warthin– in situ hybridisation Starry stain). Immunohistochemistry and also help to detect some microorganisms (see Immunohisto chemistry: infections and other applications and hybridisation ).

(b) Figure 11.23 (a) Brown pigment in a biopsy. (b) A Perls stain is posi tive, indicating that the pigment is iron.

Special stains

A ‘special stain’ is a stain that is not routine, i.e. not an H&E stain. Immunohistochemical stains are conventionally separate from this category . Some special stains demonstrate normal substances in increased quantities or in abnormal locations. The periodic acid–Schi ff (PAS) stain demonstrates both - glycogen and mucin, whereas a diastase PAS (D-PAS) stain demonstrates mucin, e.g. in an adenocarcinoma. Perls Prussian blue stain demonstrates iron accumulation ( Figure 11.23 ), e.g. in haemochromatosis. A reticulin stain helps to demonstrate fibrosis ( Figure 11.24 ). Elastic stains also show fibrosis and can highlight blood vessels by outlining their elastic laminae. Special stains can also re veal the accumulation of abnormal substances, e.g . a Congo red stain for amyloid. Summary box 11.9 Additional techniques for assessing tissue /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF Summary box 11.10 Common special stains /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF

Special stains Immunohistochemistry Electron microscopy In situ hybridisation, including /f_l uorescence in situ hybridisation (FISH) Molecular pathology techniques (including single biomarker polymerase chain reaction [PCR] and next-generation sequencing [NGS]) PAS: glycogen, fungi D-PAS: mucin Perls Prussian blue: iron Reticulin: reticulin /f_i bres, /f_i brosis van Gieson: collagen Congo red: amyloid Ziehl–Neelsen: mycobacteria

Special stains are also useful for the diagnosis of infection. Some microorganisms are not visible on routine H&E slides but are demonstrable with a stain. For example, a Ziehl–Neelsen stain demonstrates acid-fast bacilli, particularly mycobacteria, by staining them bright red on a blue background ( Figure 11.20 Other microorganisms may be detectable on H&E but are easier to see with a special stain, e.g. fungi (PAS or Grocott stain), protozoa (Giemsa stain) and spirochaetes (Warthin– in situ hybridisation Starry stain). Immunohistochemistry and also help to detect some microorganisms (see Immunohisto chemistry: infections and other applications and hybridisation ).

(b) Figure 11.23 (a) Brown pigment in a biopsy. (b) A Perls stain is posi tive, indicating that the pigment is iron.