Pathology of Pigmented Lesions

Question 1

Melanomas which appear on intermittently sun-exposed skin are most likely to have which type of mutation?

Answer 1

BRAF

(upregulates MEK and ERK which drive cell proliferation)

Question 2

During embryogenesis, melanoblasts migrate to which regions of the body?

Answer 2

Skin (mainly)

Leptomeninges

Uveal tract

Question 3

What are the leptomeniges?

Answer 3

Pia mater and arachnoid

Question 4

Which types of melanoma grow as macules?

Answer 4

Acral/mucosal lentiginous

Lentigo maligna

Superficial spreading

Question 5

What is Brelow’s thickness?

Answer 5

The deepest part of a skin tumour as measured from the granular layer

Question 6

Acral melanomas are associated with which mutation type?

Answer 6

c-kit

Question 7

What is the MC1R protein and what is its function?

Answer 7

Melanocortin 1 receptor gene

Determines balance of pigment in hair and skin by converting pheomelanin to eumelanin

Question 8

Most cases of melanoma arise ___________

Answer 8

Most cases of melanoma arise denovo

Question 9

If a melanoma is invasive and >1mm thick, how should it be excised?

Answer 9

Excise with 2cm clearance and sentinel node biopsy

Question 10

If a melanoma is foudn to be in-situ, how is it excised?

Answer 10

5mm clearance

Question 11

What is the most common type of melanoma?

Answer 11

Superficial spreading melanoma

Question 12

Where does superficial spreading melanoma normally affect on the skin?

Answer 12

Trunk and limbs

Question 13

How can dysplastic naevi be described?

Answer 13

Naevi >6mm in diameter with varigated pigment and border asymmetry

Question 14

Which type of naevus constits of pigment-rich dendritic spindle cells and is located in the dermis?

Answer 14

Blue naevi

(benign)

Question 15

Which type of naevus involves the destruction of melanocytes and high concentrations of lymphocytes which contribute to this destruction?

Answer 15

Halo naevi

Question 16

How are halo naevi created?

Answer 16

Autoimmune reaction against a naevus on the skin

Lymphocytes destroy the naevus causing it to become lighter in colour, turining pink and then eventually disappearing entirely

The immune reaction destroys surrounding melanocytes which gives the halo appearance

Question 17

Age spots are known by which other name?

Answer 17

Actinic lentigines

Question 18

What are age spots due to?

Answer 18

Long term UV exposure

Question 19

Where are melanocytes dervied?

Answer 19

Neural crest

Question 20

For which reason do freckles occur after sun exposure?

Answer 20

Reflect the clumpy distribution of melanocytes in the skin

Question 21

For freckles to be present a person requires a mutation in which gene?

Answer 21

MC1R (only one copy)

Question 22

Which naevus can mimic melanoma?

Answer 22

Spitz naevus

Question 23

Which may a Spitz naevus be dangerous?

Answer 23

Most are benign but there is a malignant variant

Question 24

In which skin layer do melanocytes reside?

Answer 24

Basal layer

Question 25

How many types of melanoma exist?

Answer 25

4

Question 26

What are the four main types of melanoma?

Answer 26

1. Superficial spreading
2. Acral/mucosal lentiginous
3. Lentigo maligna
4. Nodular

Question 27

Familial dysplastic naevi have which lifetime risk of melanoma?

Answer 27

Up to 100%

Question 28

Which suffix in Breslow’s thickness indcates ulceration?

Answer 28

b

Question 29

What are the stages of Breslow’s thickness?

Answer 29

pTis - In situ

pT1 - <1mm

pT2 - 1-2mm

pT3 - 2-4mm

pT4 - >4mm

Question 30

What risk do large malanocytic naevi pose to becoming melanomas?

Answer 30

10-15%

Question 31

Melanoma found in which loactions demonstrates poor melanocytic migration in embryogenesis?

Answer 31

Eyes

Meninges

Biliary tract

Anus

Question 32

Individuals from which ethnic background have the argest number of melanocytes in their skin?

Answer 32

There is no correlation between race and number of melanocytes in the skin