Minerals and Pigments

Question 1

What is a pigment?

Answer 1

A coloured opaque substance present in cells or tissues

Question 2

List the three main forms of pigment.

Answer 2

Artefact

Endogenous

Exogenous

Question 3

Artefact pigments are mostly due to __________ _________.

Answer 3

Chemical fixation

Question 4

True or false: formalin may leave brown artefact pigment.

Answer 4

True

Question 5

What is an endogenous pigment?

Answer 5

Pigments formed in the body, and can be distinguished as hematogenous pigments such as bile, and non-haematogenic pigments such as melanin, or lipofuschin

Question 6

Endogenous pigments are formed within the cell where they have a physiological role or are by-products of _______________.

Answer 6

Metabolism

Question 7

____________ are observed as yellow-brown intracellular granules inside cells.

Answer 7

Haemosiderins

Question 8

What stain is used to demonstrate haemosiderins?

Answer 8

Perl’s Prussian Blue

Question 9

List one condition in which excessive haemosiderins may be observed.

Answer 9

Haemochromatosis

Question 10

After ageing red cells are broken down by the reticuloendothelial system, the iron is removed from haemoglobin and the result is the formation of ____________.

Answer 10

Biliverdin

Question 11

Biliverdin is converted to ______ in liver and is stored as bile within the gallbladder.

Answer 11

Bilirubin

Question 12

‘_______ __________’ refers to bilirubin, biliverdin and haematoidin.

Answer 12

Bile pigment

Question 13

List two scenarios in which an excess of bile pigments may be found.

Answer 13

Bile duct obstruction

Abnormality of bilirubin biliverdin metabolism

Question 14

With H&E stain, bile pigments appear as __________-_______ ___________.

Answer 14

Yellow-brown crystals

Question 15

Bile pigments are identified using the ________ reaction.

Answer 15

Fouchet

Question 16

State the principle of the Fouchet reaction.

Answer 16

Ferric chloride oxidises all bile pigments to green biliverdin.T his oxidation reaction is rapidly accomplished by ferric chloride in trichloroacetic acid medium (Fouchet’s reagent). Biliverdin is then stained emerald green by acid fuchsin in van Gieson solution.

Question 17

List two non-haematological pigments.

Answer 17

Lipidic, such as lipofucsin, and non-lipidic, such as melanin

Question 18

________ is a wear-and-tear pigment.

Answer 18

Lipofucsin

Question 19

_________ ______________ is excessive storage of lipofucsin.

Answer 19

Ceroid lipofuscinosis

Question 20

What is melanin?

Answer 20

A pigment produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization

Question 21

Melanin pigments are produced in a specialized group of cells known as ______________.

Answer 21

Melanocytes

Question 22

Melanin is normally found in the ______.

Answer 22

Skin

Question 23

____________ DOPA is an intermediary pigment of melanin.

Answer 23

Tyrosine

Question 24

Melanin is produced by melanocytes in the epidermis and in skin phagocytes called ‘melanophages’ during ______________.

Answer 24

Inflammation

Question 25

Melanin production is observed in the _________ ______, the iris, and also in melanomas of the eye.

Answer 25

Ciliary body

Question 26

Melanin production is ound in the substantia niagra of the ________, with reduced amounts in Parkinson’s disease.

Answer 26

Brain

Question 27

Define 'melanoma'.

Answer 27

Abnormal growth of skin cells, which most often develops on skin exposed to the sun

Question 28

List three forms of skin cancer.

Answer 28

Basal cell carcinoma Squamous cell carcinoma Melanoma

Question 29

Sometimes, melanoma develop from a _______ with concerning changes including an increase in size, irregular edges, change in colour, itchiness, or skin breakdown.

Answer 29

Mole

Question 30

The primary cause of melanoma is __________ ______ exposure in those with low levels of skin pigment.

Answer 30

Ultraviolet light

Question 31

Name a genetic defect which increases the risk of developing melanoma.

Answer 31

Xeroderma pigmentosum

Question 32

How is melanoma diagnosed?

Answer 32

Skin biopsy of the subject lesion

Question 33

True or false: melanoma is the least concerning form of skin cancer.

Answer 33

False

Question 34

Describe the Argentaffin reaction.

Answer 34

Granules with melanin bind and reduce silver ions via Masson Fontana stain, and granules reduce ferric ferricyanide via Schmorl’s stain

Question 35

Melanoma can be bleached with ____________ ________________

Answer 35

Potassium permanganate

Question 36

State one monoclonal antibody which can be used in visualising melanoma.

Answer 36

S100

Question 37

What is HMB45?

Answer 37

An antigen on melanosomes

Question 38

List two other methods of melanoma histochemistry visualisation.

Answer 38

Enzyme methods, such as DOPA reaction Fluorescent methods

Question 39

State the principle of Schmorl's reaction.

Answer 39

Melanin will reduce ferricyanide to ferrocyanide with the production of Prussian blue, in the presence of ferric salts

Question 40

Cells that are capable of producing melanin can be demonstrated by the __________________ (DOPA) method.

Answer 40

Dihydroxyphenylalanine

Question 41

The enzyme __________, localized within cells, will oxidise DOPA to form an insoluble brown black pigment.

Answer 41

Tyrosinase

Question 42

Melanins are insoluble in most ________ solvents due to tight bonding with proteins.

Answer 42

Organic

Question 43

What is vitiligo?

Answer 43

An acquired pigmentary disorder of the skin and mucous membranes

Question 44

____________ is characterized by depigmented macules and patches.

Answer 44

Vitiligo

Question 45

Superficial perivascular and perifollicular lymphocytic ____________ may be observed at the margin of vitiliginous lesions.

Answer 45

Infiltrates

Question 46

True or false: vitiligo is frequently associated with disorders of autoimmune origin, with thyroid abnormalities being the most common.

Answer 46

True

Question 47

_______ amounts of copper are found normally in some tissues.

Answer 47

Small

Question 48

Where are increased copper deposits found in Wilson's disease?

Answer 48

Brain, liver, and eyes

Question 49

Liver staining for copper with ________ ____ shows red brown granules in hepatocytes.

Answer 49

Rubeanic acid

Question 50

What causes Wilson's disease?

Answer 50

A mutation in the Wilson disease protein (ATP7B) gene

Question 51

The ATP7B protein transports excess copper into ______, where it is excreted in waste products.

Answer 51

Bile

Question 52

Normal stores of _______ are found in bone marrow, liver, and spleen.

Answer 52

Iron

Question 53

Abnormal deposits of ___________ can be associated with atherosclerosis, sarcoid, necrotic tissues in TB infection, some tumours, and in joints in chondrocalcinosis.

Answer 53

Calcium

Question 54

What is the von Kossa method?

Answer 54

An indirect way of detecting calcium, where silver nitrate replaces the carbonate anions of calcium salts (silver substitution method). Sunlight reduces the silver salt to visible metallic silver, and unreduced silver is removed by sodium thiosulphate

Question 55

What colour do calcium deposits appear as?

Answer 55

Black

Question 56

__________ is commonly inhaled, ingested or implanted in skin following industrial exposure.

Answer 56

Carbon

Question 57

How can melanin be distinguished from carbon?

Answer 57

Melanin's colour will disappear with bleaching, but carbon's colour will remain

Question 58

Asbestos fibres are ____________ fibres of magnesium silicate.

Answer 58

Birefringent

Question 59

Where do asbestos fibres collect?

Answer 59

In alveoli at periphery of lung

Question 60

Asbestos fibres have a ___________ ______, which contains haemosiderin.

Answer 60

Proteinaceous coat

Question 61

____________ pigments are found in the skin and adjacent lymph nodes of various colours of the dye pigments seen.

Answer 61

Tattoo

Question 62

Lugol's iodine, picric-alcohol, and potassium permanganate bleach are reagents used to __________ pigments.

Answer 62

Remove

Question 63

What stain is used to demonstrate asbestos fibres?

Answer 63

Perl's Prussian Blue