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Histotechnology 2 > Pigments > Flashcards

Pigments Flashcards

1
Q

What are pigments?

A

COLOURED bodies or accumulations of substances in the tissue which do not need to be stained to be visible.

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2
Q

What are various reasons pigments can occur?

A

Pigments can occur in tissues because of:

  1. Naturally occurring
  2. Disease process.
  3. Artifacts caused by fixation.
  4. External sources.
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3
Q

What are the groups pigments are divided up into?

A
  1. ARTIFACT
    - -> Fixation
  2. NON-ARTIFACT
    a) Endogenous
    i) Hematogenous –> like hemoglobin
    ii) Non-hematogenous –> like melanin or cooper
    b) Exogenous –> like carbon
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4
Q

What are endogenous and exogenous pigments? Give an example of each.

A

Endogenous: Pigments produced within the body. Serve a physiological function or are by-products of normal metabolic process. E.g. Bile, hemosiderin, malaria, hemoglobin.

Exogenous: Pigments outside the body but gain access to inside via the nose, mouth or skin and serve no physiological function. E.g. carbon, tattoo ink, silica, mercury, aluminum, asbestos, lead.

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5
Q

What are yellow-brown granules called and what are they caused by?

A

Chromates - or dichromate’s deposits are caused by inadequate water washing after fixation in solutions containing dichromate, e.g. Zenker’s, Helly’s. Then if the tissue is transferred directly to alcohol, an insoluble oxide is precipitated in the tissue.

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6
Q

How is the exogenous pigment carbon seen in the body and where?

A

Carbon is present as black granules in the lungs of children and adults. It is often found in mediastinal and auxiliary lymph nodes and near blood vessels.

We all will have a little carbon.

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7
Q

What is the only method for removing carbon from a tissue if required?

A

Microincineration.

Large amounts of carbon are inhaled from prolonged industrial exposure, e.g. coal miners, anthracosis may develop.

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8
Q

Where do you often find formalin pigment and what is it caused by? Provide alternate name for it as well.

A
  1. Formalin pigment –> acid formaldehyde hematin (AFH)
  2. Brown-black deposits in tissue, usually concentrated w/in & around blood vessels.
  3. Produced by interaction between acidic formalin (formic acid) and hemoglobin (the heme portion).
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9
Q

How can formalin pigment (or Acid formaldehyde hematin (AFH)) be removed?

A

AFH can be removed by alcoholic picric acid.

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10
Q

What does mercury pigment look like and where can it be found and what causes it?

A

Mercury Pigment:

  1. Black-brown granules.
  2. Found throughout the tissue.
  3. Always occurs in tissue fixed in any mercuric chloride fixatives, e.g. Zenker’s, Helly’s, B5.
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11
Q

How can mercury pigment be removed?

A

Can be removed by dezenkerization.

A mixture of 0.5% iodine in 70% alcohol, then 2.5% sodium thiosulphate and water.

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12
Q

What kind of artifact can occur in general due to staining and how can it be prevented?

A
  1. Stain deposits of large blobs of stain/coloured matter seen on the tissues.
  2. Can generally be prevented by filtering stains before use.
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13
Q

What may too high of temperature do to silver stains?

A

May cause silver stains to precipitate out onto a section if too high a temperature is used during impregnation.

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14
Q

What exogenous pigment is birefringent when viewed with polarized light? Who is at risk of having this pigment and the potential outcome?

A
  1. Silica
  2. Silica is inhaled by miners.
  3. The dust particles excite a fibrous reaction in the lungs leading to a progressive pulmonary fibrotic disease known a silicosis.
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15
Q

What happens if someone inhales asbestos?

A

Asbestos (sharp) fibers of hydrated magnesium silicate are become coated with a protein-iron complex and are then called asbestos bodies.

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16
Q

What is the best way to demonstrate asbestos bodies in tissue?

A

Perl’s Prussian blue technique.

17
Q

Where might exogenous silver deposits be found and how do they appear?

A
  1. Silver deposits may be found in the skin, nasal or oral mucosa of silver nitrate workers or in patients on certain medical treatments.
  2. Appear as black or brown deposits.
18
Q

What problems can tattoo pigments cause?

A

Tatto pigments, a subcutaneous injection of dye, can be confused with other pigments and cause identification problems.

19
Q

What is the increase in storage of iron referred to as and some of the causes of it?

A

Hemosiderosis –> increase in storage of iron

Potential causes:

  • Excessive RBC destruction
  • Multiple transfusion
  • Excessive congestion
  • Decreased iron utilization
  • Localized trauma
  • Increased dietary consumption
  • Hemolysis
  • Systemic Problems
  • Chronic Wine Consumptions
  • Hemochromatosis
20
Q

What happens if the production and destruction of red blood cells is not balanced? What are the potential causes?

A

If red blood cell number not balanced, an increased deposition of hemosiderin may occur in tissues.

Potential causes:
Internal hemorrhage
Massive blood transfusions
Hemolytic anemia

21
Q

What pathologies are associated with melanin?

A

Pathologies are associated with melanin:

  1. Malignant Melanoma
  2. Albinism
  3. Lack of tyrosinase (enzyme) resulting in lack of melanin production.
22
Q

How do you tell if a slide shows malaria which is a brown-black pigment or AFH artifact?

A

If the brown-black pigments are seen:

  1. Within the cell only –> Malaria.
  2. Seen everywhere in and out of cells –> AFH
23
Q

What is the natural pigmentation colour of iron?

A

Natural pigment of iron is a yellow-brown colour.

Perl’s Prussian Blue will stain iron pigment blue which makes it easy to see on tissue.

24
Q

What can cause a false negative if staining a tissue for Perl’s Prussian Blue looking for iron?

A

Iron is soluble in acid, so if the tissue was fixed or decalcified in an acid solution prior to the tissue being stained with Perl’s Prussian Blue the Iron will be dissolved from the tissue causing a false negative result.

25
Q

What colour will hematoidin have and why?

A

HEMATOIDIN will naturally have a YELLOW colour when seen under the microscope because of the BILIRUBIN pigment.

Histotechnology 2 (10 decks)

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