Cancer as a Disease - Skin Cancer

Question 1

4 TYPES OF SKIN CANCER?

Answer 1

1. Keratinocyte derived:
2. Melanocyte derived
3. Vasculature derived
4. Lymphocyte derived

Question 2

e.g. of keratinocyte derived skin cancer? (2)

Answer 2

 Basal cell carcinoma (BCC) (most common skin cancers)

 Squamous cell carcinoma (SCC)

Question 3

e.g. of Melanocyte derived skin cancer?

Answer 3

 Malignant melanoma

Question 4

e.g. of Vasculature derived skin cancer? (2)

Answer 4

 Kaposi’s sarcoma – derived from the endothelial cells of the lymphatics (common in HIV)
 Angiosarcoma – derived from endothelial cells of blood vessels

Question 5

e.g. of Lymphocyte derived skin cancer?

Answer 5

 Mycosis fungoides

Question 6

4 causes of skin cancer?

Answer 6

Genetic conditions, viral infection, UV light and immunosuppression

Question 7

What genetic conditions can cause skin cancer?

Answer 7

Xeroderma Pigmentosum

Question 8

why is the incidence of BCC increeasing

Answer 8

Ageing population

Question 9

What type of UV is more significant in carcinogenesis

Answer 9

UVB

Question 10

which is the most penetrating uv radiation

Answer 10

UVA

Question 11

How does UV cause DNA damage

Answer 11

 Affects pyrimidines ie Cytosine (C) and Thymine (T) bases, forms Cyclobutane pyrimidine dimers e.g. T=T, T=C, C=C and 6-4 pyrimidine pyrimidone photoproducts

Question 12

What process usually repairs UV DNA damage

Answer 12

nucleotide excision repair

Question 13

how does xeroderma pigmentosum cause skin cancer

Answer 13

defective Nucleotide Excision Repair

Question 14

3 ways mutations can cause cancer?

Answer 14

1. Mutations that stimulate uncontrolled cell proliferation e.g. abolishing control of the normal cell cycle (p53 gene)
2. Mutations that alter responses to growth stimulating / repressing factors
3. Mutations that inhibit programmed cell death (apoptosis)

Question 15

What are sunburn cells

Answer 15

Sun burn’ cells are apoptotic cells in UV overexposed skin

- Apoptosis removes UV damaged cells in the skin which might otherwise become cancer cells

Question 16

What protein regulates to see if DNA is too damaged for skin cancer

Answer 16

p53

Question 17

What immunomodulatory effects does UV have

Answer 17

UVA and B deputed langerhans cells which reduces skin immunocompetence and immunosurveillance and increases cancer causing potential

Question 18

Fitzpatrick phenotypes?

Answer 18

FITZPATRICK PHENOTYPES:
I - Always burns never tans
II - Usually burns, sometimes tans
III - Sometimes burns, usually tans
IV - Never burns, always tans
V - Moderate constitutive pigmentation - Asian
VI - Marked constitutive pigmentation – Afro-Caribbean
Basically, pale skin = burns, darker skin = doesn’t burn

Question 19

What does skin colour depend on

Answer 19

amount and type of melanin produced

Question 20

how does UV cause melanin production

Answer 20

 Dendritic processes on the melanocytes communicate with the keratinocytes
 Under UV light, the keratinocyte will make more MSH and this will have a paracrine effect on the melanocyte to make more melanin
 This is packaged etc. and used by keratinocytes to protect the nucleus from DNA damage

Question 21

2 types of melanin? which type is more common in whiteos

Answer 21

1. Eumelanin – brown or black This is the one that pigments the skin
2. Phaeomelanin – yellowish or reddish brown Pale people have more of this type

Question 22

What amino acid is used to form melanin

Answer 22

tyrosine

Question 23

What gene controls melanin

Answer 23

MCR1

Question 24

What explains different hair and skin colours

Answer 24

The polymorphism of MCR1

Question 25

What is a MALIGNANT MELANOMA:

Answer 25

 Malignant tumour of the melanocytes - Melanocytes become abnormal - Atypical cells and architecture

Question 26

Causes of malignant melanoma

Answer 26

- UV exposure | - Genetic factors

Question 27

Risk of metastasising?

Answer 27

Possible

Question 28

What is LENTIGO MALIGNA

Answer 28

MELANOMA IN SITU) Proliferation of malignant melanocytes within (and restricted to) the epidermis – no risk of metastasis as they haven’t penetrated the basement membrane

Question 29

what is invasion within a lentigo maligna known as

Answer 29

lentigo maligna melanoma

Question 30

SUPERFICIAL SPREADING MALIGNANT MELANOMA risk of metastasising?

Answer 30

there is an increased risk as there is usually invasion of the basement membrane

Question 31

What is the ABCDE rule in melanomas

Answer 31

``` Asymmetry Border irregular Colour variation (dark brown-black) Diameter >0.7mm and increasing Erythema – losing of ability to make melanin in part of the tumour ```

Question 32

What is a nodular malignant melanoma

Answer 32

Vertical proliferation of malignant melanocytes with no previous horizontal growth, there is a risk of metastasis

Question 33

What is a superficial spreading malignant melanoma

Answer 33

Lateral proliferation of malignant melanocytes, invasion through the basement membrane, risk of metastasis

Question 34

What is a NODULAR MALIGNANT MELANOMA ARISING WITHIN A SUPERFICIAL SPREADING MALIGNANT MELANOMA

Answer 34

Downward proliferation of malignant melanocytes following previous horizontal growth - Nodule developing within irregular plaque - Prognosis will become worse

Question 35

What is a acral lentiginous melanoma

Answer 35

 Occur on the sole of the foot – these are the ones that occur in darker skinned individuals

Question 36

What is amelanotic melanoma

Answer 36

Melanoma lacking the ability to make melanin

Question 37

What is the prognosis of melanomas dependent on

Answer 37

Related to the thickness of the melanoma from the top of the lesion to the botton (in mm) Called BRESLOW THICKNESS - Less than 1mm = superficial - More than 1mm = deeper = higher risk of metastasis

Question 38

What is Breslows thickness

Answer 38

Melanomas relation of the prognosis to the thickness of the melanoma from the top of the lesion to the botton

Question 39

Risk factors of melanomas?

Answer 39

``` family history UV exposure sunburns intermittent burning exposure skin type 1 and 2 history of melanoma ```

Question 40

What is SQUAMOUS CELL CARCINOMA:

Answer 40

Malignant tumour of keratinocytes

Question 41

What causes SQUAMOUS CELL CARCINOMA:

Answer 41

- UV exposure - HPV - Immunosuppression - May occur in scars or scarring processes

Question 42

risk of metastasis of SQUAMOUS CELL CARCINOMA?

Answer 42

Risk

Question 43

Male high risk sites of SQUAMOUS CELL CARCINOMA:

Answer 43

ears, lips, genitals

Question 44

Female high risk sites of SQUAMOUS CELL CARCINOMA:

Answer 44

legs

Question 45

What is Keratoacanthoma

Answer 45

benign tumour that can look like SCC

Question 46

what is basal cell carcinoma

Answer 46

Malignant tumour arising from basal layer of epidermis

Question 47

Risk of metastasis of basal cell carcinoma?

Answer 47

No risk

Question 48

Causes of basal cell carcinoma

Answer 48

- Sun exposure | - Genetics

Question 49

Common area for a basal cell carcinoma?

Answer 49

face

Question 50

What is mycosis fungoides

Answer 50

If a lymphocyte restricted to tissue becomes cancerous and causes lymphoma in the skin it is called mycosis fungoides

Question 51

Presentation of mycosis fungoides

Answer 51

plaques and patches of erythematous scaley skin

Question 52

Metastasis risk of mycosis fungoides?

Answer 52

Metastasises but is slowly progressing

Question 53

What is Kaposis sarcoma

Answer 53

Tumour derived from lymph endothelium

Question 54

What drives Kaposis sarcoma

Answer 54

HHV8 virus

Question 55

What is EPIDERMODYSPLASIA VERUCIFORMIS

Answer 55

Rare autosomal recessive condition with a predisposition to HPV induced warts and SCCs (think India elephant man)