The trichrome stain is used to differentiate collagen and smooth muscle. Normal liver biopsies demonstrate tricrhome stained collagen in the portal tracts and around the central vein. In end stage liver disease (cirrhosis), the trichrome stain will demonstrate a marked increase in collagenous tissue, referred to as fibrosis.
Trichrome stains include the use of three dyes. Procedural steps include a mordant, nuclear dye, cytoplasmic dye, acid link, collagen dye, and acid differentiator. Two commonly used collagen stains are analine blue and light green; light green is a better collagen stain when collagen is predominant. The trichrome stain used to demonstrate collagen fibers for this course is the Masson's trichrome. Reagents used in the Masson method are as follows:
- Mordant: Bouin's solution
- Nuclear dye: Weigert's hematoxylin
- Cytoplasmic dye: Beibrich Scarlet acid fuschin
- Acid link: Phosphomolybidic/phosphotungstic acid
- Collagen dye: Analine blue
- Acid differentiator: Acetic acid solution
In the image, a liver biopsy stained with Masson's trichrome stain demonstrates an increase in collagenous tissue in a patient with inactive cirrhosis.