Pigment Flashcards
What are the three groups of pigment?
- Artifact
- Endogenous
- Exogenous
What are the two subgroups of endogenous pigments?
a. Hematogenous
b. non-hematogenous
Non hematogenous pigments can be subdivided into two categories?
- Lipidic
- Non-lipidic
What are examples of artifact pigments?
- Formalin pigments
- Mercury pigments
- Chrome pigments
What are examples of hematogenous pigments?
- Hemoglobin
- Hemosiderin
- porphyrins
- bile pigments
What are examples of non-hematogenous pigments?
- Melanin (NL)
- Lipofuchsin (L)
- Ceroid (L)
What are examples of exogenous pigments?
- Carbon
- Asbestos fibers
- Tattoo pigments
- Metals
How are artifact pigments formed?
Usually from fixation
What are exogenous pigments?
Formed externally and taken into the body
How are formaldehyde pigments formed?
During fixation using acidic formaldehyde solutions.
How can formaldehyde pigments be removed?
With saturated alcoholic picric acid prior to staining
How are mercuric pigments formed?
While fixing with mercuric fixatives.
How can mercuric pigments be removed?
Iodine solution followed by sodium thiosulphate.
What do hemosiderin pigments look like?
yellow / brown
Where might hemoglobin be seen, and what stain does it have an affinity for?
- renal tubules post HA and recent hemorrhages
- stains vividly with acidic dyes
List two methods which will demonstrate iron.
- Prussian Blue
- Turnbull’s blue reaction
How are bile pigments demonstrated?
By oxidizing bilirubin (yellow/brown) to a greenish biliverdin
Where is Melanin found in the human body?
- Hair
- Skin
- Retina
- Iris
- CNS
What is a malignancy related to melanin called?
Melanocarcinoma
What is the principle behind lipofuchsins.
Slow progressive oxidation process of lipids and lipoproteins, into a brown pigment.
Which demonstration methods are useful for lipofuchsins?
- PAS
- Oil Red O
- SBB
- Schmorl’s
- Long Ziehl-Neelson
What are ceroids?
Yellow/brown pigments that are rarely seen in humans, and are positively stained by acid fast staining methods.
What are trophi?
Large amount of Uric acid and urate crystals which are deposited in soft tissue
How can sodium urates be fixed for demonstration?
Requires alcohol fixation
What principle can be employed to demonstrate urates?
Argentaffin - Methenamine silver method
What are neuroendocrine cell’s? and what might be demonstrated in these cells?
- Adrenal chromaffin cells
- Endocrine cells
- Enterochromaffin cells (GI)
- “C” cells of the thyroid
- Pituitary cells
—-> Cytoplasmic granules <—-
How can cells of the neuroendocrine be demonstrated?
- Argentaffin / Argyrophilic reactions
Which minerals can be demonstrated by special stains?
- Calcium
- Ferric iron and Ferrous Iron
- Copper
- Phosphate
- Carbon (trioxide??)
What is the purpose of Pearl’s Prussian blue technique?
Demonstrate ferric iron in tissue
What is the principle of Pearl’s Prussian blue technique?
Detect ferric iron in bound protein complex, endpoint reaction being insoluble coloured pigment.
Which fixative is ideal for Pearl’s Prussian blue technique?
- Alcohol
- NBF