Staining of tissue deposits and pigments

• Endogenous pigments


  produced within the tissue to serve a physiological function, or may be by-products of normal metabolism.
• hematogenous

  hemosiderin, hemoglobin, bile pigment
• nonhematogenous

  iron, calcium and copper
• Exogenous pigments


  consist of foreign materials, usually minerals introduced to the body thru air, food, medication and injections
• Carbon is the most common exogenous pigment, appearing as jet black pigments in lung sections and bronchial glands of chronic smokers
• Iron may be present as an endogenous pigment in the liver in case of iron overload, or may be an exogenous pigment in the case of shrapnel wound.
• Artifact pigments


  lie on top of tissue instead of within the cell. They are produced in tissues during processing and most commonly result from fixation. Formalin pigment occurs when tissue is fixed in acidic formaldehyde solutions.
• Hematoidin


  iron-free pigment of hemoglobin, found in places where there is poor oxygenation, participating in the formation of bile pigment.
• Hematin


  - is hemoglobin minus the globin molecule, found in old blood clots, but may be encountered in malaria, pernicious anemia, and toxic hemolysis
• Hemozoin


  - is the black granule formed by malarial parasites living in red blood cells, and may be removed by alcoholic picric acid method.
• Lillie’s Method for Ferric and Ferrous Iron

  Ferric iron - Dark Prussian blue

  Ferrous iron - Dark Turnbull’s blue

  Background - light Red
• Perl's Prussian Blue Method for Hemosiderin (ferric iron)

  Hemosiderin and ferric salts stain - deep blue

  Other pigments retain their - natural color

  Tissues and nuclei stain red (according to counterstain)
• Gomori's Prussian blue Stain for Iron

  Iron pigments - bright blue

  Nuclei - red

  Cytoplasm - pink to rose
• Turnbull's Blue for Ferrous Iron

  Ferrous iron – blue

  Nuclei – red
• Leuco patent blue V Stain for Hemoglobin

  Hemoglobin peroxidase (RBCs and neutrophils) - dark blue

  Nuclei - red
• Modified Fouchet's Technique for Liver Bile Pigments

  Muscle - green yellow

  Collagen - red
• Gmelin Technique for Bile and Hematoidin

  Bile pigments will gradually produce the following spectrum of color change: yellow-green-blue-purple-red
• Gomori's Aldehyde Fuchsin Technique for Lipofuscin

  Lipofuscin - purple

  Background - yellow
• Mallory's Fuchsin Stain for Hemofuscin Pigment

  Nuclei - blue

  Hemofuscin - red

  Hemosiderin - unstained
• Masson-Fontana Method for Melanin

  Melanin - black

  Argentaffin - granules black

  Nuclei - red
• Modified Von-Kossa’s Method for Calcium

  Mineralized bone - Black

  Osteoid - Red

  Nuclei - blue
• Alizarin Red S Method for Calcium

  Calcium salts - intense reddish-orange

  Background - pale green
• Lindquist's Modified Rhodanine Technique for Staining Copper

  Copper and copper associated protein - red to orange-red

  Nuclei - blue

  Bile - green
• Formaldehyde deposits


  fine, dark-brown or black crystal-like precipitates, often with no relationship to the tissue
• Formalin deposits


  The pigment deposits are birefringent in polarized light
• Mercuric Chloride Deposits

  presence of large irregular clumps of black precipitate on slides of tissues fixed in a mercurial fixative suggests that the tissues were not "dezenkerized" prior to staining
• Osmium Tetroxide Deposits

  black deposits on tissues which have not been properly washed out. To remove by bleaching
• Chrome deposits


  fine brown or black granules in chromate (i.e., Zenker’s) fixed tissues.

  They may be removed from the tissues by washing them out from sections with the use of acid alcohol
• Chrome deposits can be prevented by washing tissue in running tap water prior to dehydration.
• Silica


  found most commonly in the lungs and associated lymph nodes of stone grinders. In coal miners, it occurs together with carbon, which presents as anthracosis
• Silica pigment occurs as grayish crystals that are birefringent
• Asbestos


  special type of long-thin silica crystal found in the lungs and associated lymph nodes of asbestos workers
• Mesotheliomas


  tumors of the serous membranes (peritoneum, pericardium and pleura) that are often related to asbestos exposure
• Starch or talcum powder


  pigment usually introduced by talc from the gloves of a surgeon, nurse, or pathologist.
• PAS- and GMS positive and can be easily identified by its characteristic appearance, which includes a “Maltese cross” configuration when polarized
• Talcum powder has an affinity for the dyes auramine O and rhodamine B, and will fluoresce yellow when viewed with a fluorescence microscope.