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Canc > Cancer 15: Skin cancer > Flashcards

Cancer 15: Skin cancer Flashcards

1
Q

Outline the microanatomy of the skin

A

Epidermis:

  • stratum corenum
  • stratum granulosum
  • stratum spinosum
  • stratum basale

Dermis (contains glands and hair follices)

Hypodermis (blood vessels)

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2
Q

Where do most cancers aruse from in the skin

A

Epidermis

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3
Q

Which cells are present in the epidermis

A

Keratinoytes… prolferate and move up the epidermis until they become the stratum corneum- so stem cells in stratum basale

Melanocytes

Merkel cells (mecahnoceptors detecting light touch)

Langerhans cells (dendritic cells- prominent in stratum spinosum)

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4
Q

Outline the cancers derived from keratinocytes

A

Non-melanocyte skin cancer:

basal cell carcinoma
squamous cell carcinoma

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5
Q

Outline melanocyte derived cancer

A

Malignant melanoma

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6
Q

List vasculature derived tumours

A

Kaposi’s sarcoma, angiosarcoma

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7
Q

List a type of lymphocyte derived cancer

A

Mycosis fungoides

NOT fungal infection (a skin lymphoma)

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8
Q

Cause of skin cancer

A

Accumulation of genetic mutations

leads to
uncontrolled cell proliferation

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9
Q

Examples of causes of skin cancer

A

Genetic syndromes
Viral infection
UV light
Immunosuppression

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10
Q

Examples of genetic syndromes leading to skin cancer

A

Gorlin’s syndrome (Basal cell)

xeroderma pigmentosum (DNA repair system malfunction)

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11
Q

Examples of viruses leading to skin cancer

A

HHV8 in Kaposi’s sarcoma

HPV in SCC

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12
Q

Examples of UV light causing skin cancer

A

BCC, SCC, malignant melanoma

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13
Q

Examples of immnosuppression causing skin cancer

A

drugs, HIV, old age, leukaemia

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14
Q

Look at malignant melaona

Compare to squamous cell

A

Malignant melanoma (streaks/different coloured areas)

Swuamous cell pearly and veins on surface

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15
Q

What skin type is malignant melanoma most common in

A

White people and increasing

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16
Q

What is happenng t BCC

A

Increasing

Common on face
Has increased since people stopped wearing hats

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17
Q

Which UV rays are we exposed to

A

UVA and UVB

UVA most penetrative can go down to sea level

UVB most important for for skin cancer

UVC filtered out by the ozone layer

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18
Q

What is the spectrum of visible light

A

400-700

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19
Q

Why is UV essential for life

A

Essential for photosynthesis (plants)
Infrared spectra provide warmth
Effect on human mood
Stimulates the production of vitamin D in the skin

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20
Q

Why are UVB and UVA important

A

UVB:
most important wavelength in skin carcinogenesis

UVA:major cause of skin ageing
contributes to skin carcinogenesis
used therapeutically in PUVA therapy

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21
Q

How does UVB usually affect DNA

A

UVB directly induces abnormalities in DNA eg mutations

UVB induces photoproducts (mutations)
-Affects pyrimidines ie Cytosine (C) and Thymine (T) bases
cyclobutane pyrimidine dimers eg T=T, T=C, C=C

-6-4 pyrimidine pyrimidone photoproducts

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22
Q

Why is UVB normally not a problem for DNA

A

The damage is usually repaired quickly by nucleotide excision repair

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23
Q

Outline affect of UVA on skin carcinogenesis

A

Also promotes skin carcinogenesis

DNA forming cyclobutane butane pyrimidine dimers but less efficiently than UVB

free radicals which damage DNA and cell membrane (including langerhans)

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24
Q

How can the UV damage to DNA lead to cancer i.e. which specific genes

A

UV damage to DNA leads to mutations in specific genes

cell division
DNA repair
cell cycle arrest

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25
Q

How can the UV damage to DNA lead to cancer

A

UV damage to DNA leads to mutations in specific genes
cell division
DNA repair
cell cycle arrest

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26
Q

Photoproducts are removed by what. When is this a problem

A

Photoproducts are removed by a process called Nucleotide Excision Repair

Xeroderma pigmentosum
=Genetic condition with defective Nucleotide Excision Repair

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27
Q

Mutations causing skin cancer more generally (i,e not just in UV)

A

Mutations that stimulate uncontrolled cell proliferation
Eg abolishing control of the normal cell cycle (p53 gene)

Mutations that alter responses to growth stimulating / repressing factors

Mutations that inhibit programmed cell death (apoptosis)

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28
Q

What happens in sun burn

A

UV leads to keratinocyte cell apoptosis

‘Sun burn’ cells are apoptotic cells in UV overexposed skin

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

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29
Q

Outline photocarcinogenesis

A

Usually skin cell with DNA damage due to UV rays will have DNA repaired, so it dosn’t develop cancer phenotype

If the damage is too severe it will apoptose,

in a p53 mutation, there is inactivated wild type

Skin cancer

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30
Q

As well as directly inducing DNA mutations, what other effect of UV light in the skin

A

IMMUNOMODULATORY

31
Q

Outline the immunomodulatory effect of UV light

A

UVA and UVB effect the expression of genes involved in skin immunity

Depletes Langerhans cells in the epidermis

Reduced skin immunocompetence and immunosurveillance

Basis for UV phototherapy for eg psoriasis

Further increases the cancer causing potential of sun exposure

32
Q

What is the use of UV light in psoriasis

A

Down regulating langerhans cells reduces skin immunocompetence and immunosurveilance (UV A and UVB)

And this will reduce the inflammatory response

33
Q

Outline photocarcinogenesis with regard to UV

A

So we had that UV induces mutations in key regions such as p53 and the other types of genes (cell division, DNA repair
, cell cycle arrest)

But normally and immune reponse would be mounted against this skin cancer

But if there is UV damage to langer hans cells this will not happen so no cell death

34
Q

What determines the host response to UV

A

Phototype

Fitzpatrick (1-6) depends how dark you are

35
Q

What determiens skin colour

A

Amount of melanin and the type of melanin

36
Q

How is melanin produced

A

By melanocute in the stratum basale (dendritic cell)

….. FINISH

37
Q

What happens in th eevent of sun exposure

A

Keratinocytes release MSH

Stimuates melanocytes to release melanin from melanosomes wich then are released from dendrtic process of the melanocyte

38
Q

T/F there is difference in the meanocyte number between light and dark skinned people

A

F

39
Q

What are the two types of melanin

A

Eumelanin – brown or black

Phaeomelanin – yellowish or reddish brown

40
Q

What affects the expression of eumelanin or phaeomelanin

A

MCR1 gene
>20 gene polymorphisms
Variation in eumelanin : phaeomelanin produced
Explains different hair colour and skin types

41
Q

How is melanin produced

A

Melanin is formed from tryosine via a series of enzymes

42
Q

what dictates skin sensitivity to UV damage

A

MELANIN

43
Q

Outline malignant melanoma

A

Melanocytes become abnormal
Atypical cells and architecture

by UV exposure
Genetic factors

Risk of metastasis

44
Q

What is lentigo maligna

A

Melanoma in situ

Proliferation of malignant melanocytes within the epidermis

No risk of metastasis

Usually flat and dark

45
Q

What is it called if lengigo is malignant FNISH

A

Lentigo maligna melanoma

46
Q

What is a superficial spreading malignant melaonma

A

Lateral proliferation of malignant melanocytes

Invade basement membrane

Risk of metastasis

47
Q

What is ABCDE rule

A 
Asymmetry
Border irregular
Colour variation (dark brown-black)
Diameter >0.7mm and increasing
Erythema
48
Q

Why can there be a white patch in the middle of the lesion…. good or bad

A

Immune response has been mounted against it

Good bcause there is a immune response

Bad because it might mean the melanoma has gone deeper

49
Q

What is a nodular melanoma

A

Vertical proliferation of malignant melanocytes
(no previous horizontal growth)

Risk of metastasis

50
Q

When is prognosis worse with malignant melaonma

A

Nodule developing within irregular plaque (i,e, nodular within superifical spreadng)

Prognosis will become WORSE

51
Q

Why could you get erythema in malingnat melanoma

A

……

52
Q

What is acral lentiginous melanoma

A

Acral lentiginous melanoma (ALM) is a specific type of melanoma that appears on the palms of the hands, the soles of the feet, or under the nails

53
Q

What is amelanotic melanoma

A

Amelanotic melanoma

When the migantn cells lose ability to make melanin

54
Q

Types of malignant melanoma

A 
Superficial spreading
Nodular
Lentigo maligna melanoma
Acral lentiginous
Amelanotic
55
Q

What is breslow thickness

A

How far down the melanoma goes affects the prognosis

56
Q

Important risk factors for melanoma developent

A 
Family hisotry 
Personal hostry 
Skin type I,II 
Sunburns during childhood 
Do they have lots of moles (atypical nervus syndrome)
57
Q

What is keratocanthoma

A

Lumps which grow quickly and then fall off

Benign

58
Q

What could keratocanthoma look like SCC

A

…..

59
Q

When is SCC worse

A

When worse differentiated (when the lump doesn’t have a core)

Having a horn or core is good

60
Q

What us SCC

A

Malignant tumour of keratinocytes

61
Q

Case of SCC

A

UV exposure

HPV

Immunosuppression

May occur in scars or scarring processes

62
Q

High risk site for SCC

A

Ears for men (not covered by hair)

Lips

Genital regions

63
Q

What is a commons site of SCC for women

A

Legs (low risk malingancy)

64
Q

What SCC is worse

A

If just a lump not horns or a core

65
Q

What is basal cell carcinoma and cause, compare to SCC

A

Malignant tumour arising from basal layer of epidermis

Sun exposure and genetics

BCC invades tissue but DOES NOT METASTASISE, relatively slow growing

66
Q

Why are basal cell carcinoma not havig horns or a core

A

Don’t make keratin so not rough or horny

67
Q

Where do basal cell carcinomas commonly occur

A

On the eye (incluidng eye lashes)

68
Q

Outline the vascularitsation on basal cell carcinoma

A

Looks like a tree

Arbarising telangiotectasia

69
Q

T/f BCC can incade

A

Invades tissue, but does not metastasise

Slow growing

70
Q

Where are BCC common

A

Common on face

71
Q

What will be seen under microscpe in mycosis fungoides

A

Lymphocytes in the dermis and epidermis….

CHECK

slow progressive disease

72
Q

What kaposis sarcoma

A

HIV and HHV8 associated

Spread to gut liver and lung

73
Q

What is epidermodysplasia veruciformis

A

Rare autosomal recessive condition

predisposition to HPV induced warts and SCCs

Canc (16 decks)

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