Week 8 - Melanoma

Question 1

What is the malignant form of skin cancer?

Answer 1

Melanoma

Question 2

What guide classifies pigmented lesions?

Answer 2

Clarks Classification of Pigmented Lesions

Question 3

Name the two growth phases of pigmented lesions.

Answer 3

Radial Growth Phase - Thin

Vertical Growth phase - Thicker - capable of metastasis

Question 4

What are the characteristics of an atypical naevus and what how many of these characteristics need to be present for the classification to be true?

Answer 4

1. Size >5 mm diameter
2. Ill-defined or blurred borders
3. Irregular margin/unusual shape
4. Varying shades of colour (pink, tan, brown, black)
5. Flat and bumpy components

Any 3 or more.

Question 5

What cells are affected in non melanoma skin cancers and what cells do melanomas affect?

Answer 5

NM Skin cancer - Keratinocytes

Melanoma - Melanocytes

Question 6

Which out of VGP and RGP is capable of metastasis?

Answer 6

VGP

Question 7

Where is the Clark phase used and where is it not and why?

Answer 7

Used in research as they represent biological changes.

Not used in clinical diagnosis as there is a quicker diagnostic method - Breslow Thickness

Question 8

What is Breslow Thickness?

Answer 8

The height of the lesions from the granular layer of the epidermis to base of the tumour - Stronger association with prognosis.

Question 9

Name the different stages of melanoma, their diagnostics and their 5 year survival rates.

Answer 9

Stage 1 - in-situ or < 1mm thick - 100% survival rate

Stage 2 - Thicker ulcerated but no no affected lymph nodes detected - 80%

Stage 3 - Affected lymph nodes (palpable) - 52%

Stage 4 - Distant metastaes - 8% (M) & 25% (F)

Question 10

Where is Melanoma incidence most common and least common (general areas)?

Answer 10

Most - Europe, North America and Oceania

Least - Asia, Africa, Carribean

Question 11

What is a Melanocyte?

Answer 11

Cells that sit in the Stratum Basale region of the skin and produces the pigment melanin which is responsible for skin colour.

It organises the transfer of melanosomes (melnanin filled transport organelles) to basal keratinocytes.

Question 12

Name 4 established associations between sunlight/UV and melanoma.

Answer 12

1. Incidence varies with latitude - For a given skin type, the nearer the equator, the higher the incidence.
2. Skin type is important - incidence higher in white-skinned races.
3. Sun exposure habits affect risk - Sunburn, especially in children, is a risk factor - So is use (ever) of a sunbed (1.75 x) - Intermittent sun exposure worse than constant (e.g. trunk > face; indoor workers > farmers etc).
4. Melanomas rare on body areas never exposed to sunlight.

Question 13

Name three types of UV rays and rank them by shortest to longest UV wavelength.

Answer 13

1. UVA
2. UVB
3. UVC

Question 14

Out of the 3 UV rays, what are their properties and which is the filtered least by the Ozone?

Answer 14

UVC - Very harmful
UVB - Harmful to DNA, protein but most absorbed by atmosphere and epidermis
UVA - Passes through epidermis, some damage to dermis and some DNA effects.

Question 15

Which out of the UV rays cause single and double stranded DNA breaks?

Answer 15

UVA and UVB

Question 16

What is UVA’s interaction with melanin that causes DNA damage?

Answer 16

It causes melanin to release reactive oxygen species e.g. pheomelaning which causes DNA damage.

Question 17

What genetic variant gives rise to higher relative risk to melanoma?

Answer 17

MC1R vairants - red/fair hair and pale skin - x3 increased risk

Question 18

What factor increases the relative risk to melanoma by 20-30x?

Answer 18

Many benign naevi (>100 when young)

Question 19

What is the FAMMM syndrome, what gene is affected, and what is the increased risk of melanoma?

Answer 19

Familial atypical moles and malignant melanoma

CDKN2A gene mutation

Increased risk by 100-400x