Skin Cancer Flashcards

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1
Q

What are the 2 main types of skin cancer?

A

Melanoma and keratinocyte (non-melanoma) skin cancers

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2
Q

What are the 2 types of keratinocyte/non-melanoma skin cancers?

A

Basal cell carcinomas (BCC)

Squamous cell carcinomas (SCC)

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3
Q

Which cells do the following skin cancers originate from?

  • Basal Cell Carcinoma
  • Squamous Cell Carcinoma
  • Melanoma
A

BCC -> cells in the basal layer of the epidermis

SCC -> suprabasal cells in the epidermis

Melanoma -> melanocytes in the basal layer of the epidermis

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4
Q

Skin cancer is the second most common human cancer. T/F?

A

False

It is the most common (1/3 of all cancers)

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5
Q

Which of the 2 main types of skin cancer is the most common?

A

Keratinocyte (non-melanoma) -> makes up >90% of skin cancers

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6
Q

Incidence of both melanoma and keratinocyte/non-melanoma skin cancer is increasing. T/F?

A

True

Keratinocyte is incidence increasing the most

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7
Q

What are benign collections of melanocytes called?

A

Melanocytic naevi or moles

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8
Q

Why are melanomas more likely to metastasize than keratinocyte cancers? (2)

A

Melanocytes are motile cells that move around

Metastatic melanomas respond poorly to chemo and radiotherapy

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9
Q

Which cancer treatments are most useful for melanomas?

A

Targeted therapy and immunotherapy

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10
Q

What is the most important prognostic factor for melanoma survival?

A

Tumour depth

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11
Q

What is Breslow’s Thickness?

A

A measurement of depth of a melanoma vertically from the top of the granular layer to the deepest point of tumour involvement

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12
Q

What is the 5-year survival for a melanoma with…

  • Breslow’s thickness <1mm
  • Breslow’s thickness >4mm
  • Metastases
A

Breslow’s thickness <1mm -> >95%

Breslow’s thickness >4mm -> 50%

Metastases -> 5%

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13
Q

What is the ABCDE rule for diagnosing a melanoma early?

A
Asymmetry
Border (irregular)
Colour (irregular)
Diameter
Evolution
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14
Q

Why is the ‘evolution’ of ABCDE so important?

A

Normal moles change slowly over years whereas melanomas evolve rapidly over several weeks or months

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15
Q

What is the ‘ugly duckling’ sign of a melanoma?

A

A mole that looks different from all the others

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16
Q

What is atypical mole syndrome?

A

A genetic condition where family members have a large number of moles which are hard to monitor

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17
Q

What surveillance technique is recommended for families with atypical mole syndrome?

A

Mole mapping (regular photographing) to observe for rapidly changing moles

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18
Q

What are the differences in the patient groups most likely to be affected by BCC and SCC?

A

BCC -> younger patients (~40y/o) with intermittent episodes of severe sunburn e.g., annually on holidays

SCC -> older patients with cumulative sun damaged skin

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19
Q

Which keratinocyte skin cancer is most likely to metastasize?

A

SCC

BCC can be locally invasive but don’t usually spread

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20
Q

BCC is usually treated successfully with…

A

Surgical excision

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21
Q

Which keratinocyte skin cancer grows faster?

A

SCC

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22
Q

What is the most common type of BCC? Describe its appearance

A

Nodular/ nodulocystic BCC

A well-defined, raised nodule which is…

  • Shiny
  • Translucent
  • Has telangiectasia
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23
Q

Describe the appearance of these less common forms of BCC…

  • Rodent ulcer
  • Superficial
  • Morphoeic (infiltrative)
  • Pigmented
A

Rodent ulcer -> ulcer with a shiny, telangiectasic border

Superficial -> similar to a small patch of dermatitis, makes it hard to diagnose

Morphoeic (infiltrative) -> looks like a scar with an ill-defined border

Pigmented -> resembles a melanoma

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24
Q

What are the most common clinical presentations of a SCC? (2)

A

A hyperkeratotic (crusted) lump or an ulcer

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25
Q

Name 2 precursor lesions for SCC (carcinoma-in-situ)

A

Actinic keratoses

Bowen’s disease

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26
Q

What is keratoacanthoma?

A

An unusual form of SCC which grows for around 3 months and then self-resolves

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27
Q

What are the highest risk sites for SCC?

A

Ear (most likely to metastasize)
Lip
Scalp

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28
Q

Where do SCCs most commonly metastasize to?

A

Regional lymph nodes (most common)

Bone

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29
Q

Keratinocyte skin cancers may also arise in areas of…

A

Chronic ulceration, scarring or burns

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30
Q

Actinic keratoses are very common. T/F?

A

True

1/3 of men in the UK >70y/o have them

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31
Q

Describe the appearance of actinic keratoses

A

Multiple small, red and scaly patches of skin found on sun-exposed areas of skin

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32
Q

Actinic keratoses are strongly associated with risk of developing SCC only. T/F?

A

False

It is associated with high risk of developing both SCC and BCC

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33
Q

Describe the appearance of the lesions in Bowen’s disease

A

An erythematous plaque, often found as a single lesion on the leg

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34
Q

Describe the histology of Bowen’s disease

A

Shows full thickness epidermal dysplasia but no invasion into the dermis

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35
Q

Bowen’s disease is strongly associated with risk of developing SCC only. T/F?

A

True

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36
Q

What are Bowenoid actinic keratoses?

A

Multiple actinic keratoses which have full thickness epidermal dysplasia

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37
Q

What are the 4 main categories of risk factors for developing a skin cancer?

A
  1. Sun exposure/ skin type
  2. Genetic susceptibility
  3. Immunosuppression
  4. Other environmental carcinogens
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38
Q

What is xeroderma pigmentosum?

A

A genetic disease characterised by a defect in 1 of the 7 nucleotide excision repair (NER) genes

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39
Q

Why is xeroderma pigmentosum strongly associated with skin cancer?

A

Defect in NER genes means that DNA damage caused by UV exposure is unable to be repaired

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40
Q

What are the symptoms of xeroderma pigmentosum?

A
  • Photosensitivity in babies (i.e., crying in sunlight)
  • Severe sunburn
  • Early photoaging
  • Neurological degeneration
41
Q

What is oculocutaneous albinism?

A

An autosomal recessive disease characterised by absence of melanin

42
Q

What are the symptoms of oculocutaneous albinism?

A
  • Sun sensitivity
  • Skin cancer
  • Visual defects (due to lack of pigment in retina)
43
Q

What is naevoid basal cell carcinoma (Gorlin’s) syndrome?

A

An autosomal dominant disease caused by mutation in the PTCH gene (a tumour suppressor gene)

44
Q

What is the major symptom of Gorlin’s syndrome?

A

Early onset of multiple BCC’s

45
Q

If a child with recessive dystrophic epidermolysis bullosa (RDEB or butterfly disease) survives till adulthood, which skin cancer are they at high risk of developing?

A

Squamous cell cancer

46
Q

The risk of developing SSC is increased by X-Y fold in an organ transplant recipient

A

100-200

47
Q

List some other environmental carcinogens that can cause skin cancer

A
Coal tar
Smoking
Ionising radiation
Arsenic
Trauma 
Chronic ulceration
48
Q

What are the 4 main methods for skin cancer prevention?

A
  1. Behaviour - avoid sun at its height, keep to the shade, avoid sunbeds
  2. Clothing - wear a hat, fully covering, loose clothing, dark clothing
  3. Sunscreens - high SPF with UVA protection, multiple applications
  4. Regular self-surveillance
49
Q

What are the hallmarks of cancer?

A
  1. Sustaining proliferative signalling
  2. Evading growth suppressors
  3. Invasion and metastases
  4. Enabling replicative mortality
  5. Inducing angiogenesis
  6. Resisting cell death
  7. Avoiding immune destruction
  8. Genome instability and mutation
50
Q

Name a common oncogene and a common tumour suppressor

A

Oncogene - Ras

Tumour suppressor - p53

51
Q

What does p53 do in a normal cell?

What happens if p53 is non-functional?

A

DNA damage would normally activate p53 to halt the cell cycle and cause apoptosis of the damaged cell if the damage could not be repaired

Damaged (mutated) DNA will be passed on if p53 is not working

52
Q

What does Ras do in a normal cell?

How can it act as an oncogene?

A

Ras binds to growth factor receptors to cause cell division and proliferation

If Ras is switched on permanently, there is a constant signal for cells to proliferate

53
Q

Why are some mutated, clonal p53 patches found in normal appearing human skin?

A

Clonal expansion of mutant p53 cells can be seen on sun-exposed sites as it is driven by UV light

54
Q

Skin type is determined by the types of melanin found in the skin. Which type of melanin is found in lighter skin and which type is found in darker skin types?

A

Lighter skin = more eumelanin

Darker skin = more pheomelanin

55
Q

Which skin cancer type is seen in the older population. Why?

A

SCC

As risk arises from lifetime cumulative UV exposure

56
Q

Which skin cancer type is associated with intermittent burning episodes of sun exposure and sunbed use?

A

BCC and melanoma

57
Q

What % of cases are found on less exposed sites in…

  • SCC
  • BCC
  • Melanoma
A

SCC - <10%

BCC - <40%

Melanoma - <60%

58
Q

Which form of UV light causes direct DNA damage?

A

UVB

UVA causes indirect oxidative damage

59
Q

UVB light penetrates more deeply into the skin. T/F?

A

False

UVA -> longer wavelength but penetrates the ozone layer more easily so there is more in the atmosphere

UVB -> shorter wavelength but only penetrates the ozone layer when it is directly overhead

60
Q

What are the 2 major types of UVB-induced DNA damage?

A

Cyclobutane pyrimidine dimers (CPDs) -> most common

Pyrimidine-pyrimidine (6-4) photo-products

61
Q

How are CPDs and 6-4 photo-products formed?

A

By covalent bonding between adjacent pyrimidines (C and T) on the same DNA strand

62
Q

What are the UVB-signature mutations?

A

C-T or CC-TT

63
Q

How are CPDs and 6-4 photo-products normally removed from DNA?

A

By nucleotide excision repair (NER)

64
Q

What is the most common indirect DNA damage caused by UVA?

A

Oxidation of DNA bases, especially deoxyguanosine to 8-oxo-deoxyguanosine

65
Q

How is oxidation of deoxyguanosine to 8-oxo-deoxyguanosine repaired?

A

By base excision repair

66
Q

Which point mutation is often caused by UVA damage?

A

C -> A

67
Q

How does chronic UV exposure cause immunosuppression of the skin? (3)

A

Keratinocytes secrete IL-10 and other immunosuppressive cytokines

Langerhans cells lose their antigen presenting ability and become depleted in number

T-reg cells with immune suppressive activity are generated

68
Q

Why are targeted treatments especially useful for BCC?

A

It is caused by a single mutation

69
Q

Which pathway are PTCH and SMO found in and what does it cause?

A

The hedgehog signalling pathway

Leads to cell proliferation and angiogenesis

70
Q

What are the 2 different mutations that can cause BCC?

A

Inactivation of PTCH (90%)

Activation of SMO (10%)

71
Q

Which 2 genes are linked to familial melanoma?

A

CDKN2A (tumour suppressor)

CDK4 (oncogene)

72
Q

What is the most common sporadic mutation in melanoma?

A

An activating B-Raf mutation (the V600E mutation of B-Raf)

73
Q

Which 2 drugs target mutated B-Raf?

A

Vemurafenib and Dabrafenib

74
Q

Why is a MEK inhibitor (Trametinib) also prescribed alongside a B-Raf inhibitor?

A

As the cancer is good at evolving to evade the targeted treatments

75
Q

How to anti-PD1/PDL1 immune checkpoint inhibitors work in targeted melanoma therapy?
Give an example of one

A

They prevent co-stimulation of T cells so they are not activated

E.g., Ipilimumab

76
Q

How does azathioprine cause skin cancer?

A

It is an immunosuppressant and a photosensitiser

77
Q

What is Imiquimod and what can it be used for?

A

A topical treatment for actinic keratoses, warts and SCC which works by up-regulating the immune system

78
Q

What is 5-Fluorouracil and what can it be used for?

A

A topical or injection chemotherapy medication which can be used for skin cancers

79
Q

List possible therapies for skin cancer

A
  • Surgery
  • Photodynamic therapy
  • Cryotherapy
  • Chemo/radiotherapy
  • 5-Fluorouracil (topical chemo)
  • Imiquimod (immune system up-regulation)
80
Q

List the most common treatment options for precancers

A
  • Cryotherapy (freeze therapy)
  • Solaraze (anti-inflammatory)
  • 5-Fluorouracil (topical chemo)
  • Photodynamic therapy
  • Imiquimod (up-regulates immune system)
81
Q

What are the 5 layers of the scalp and what pneumonic is used to remember them?

A

SCALP

Skin
Connective tissue
Aponeurosis
Loose connective tissue
Periosteum
82
Q

Which methods of local anaesthesia may be used prior to commencing skin cancer surgery?

A

Topical
Local infiltration
Nerve block (numbs the area it supplies)
Field block

83
Q

What is the most common anaesthetic used in skin cancer surgery?

A

Lignocaine (aka lidocaine)

84
Q

Why is adrenaline used alongside a local anaesthetic? (2)

A
  • Prolongs anaesthesia

- Reduces bleeding

85
Q

When should adrenaline not be used alongside local anaesthetic? (3)

A
  • In fingers and toes
  • In patients with cardiac disease
  • In patients on psychotropic drugs
86
Q

What is the best way to reduce pain during injection of local anaesthesia?

A

Make sure the patient is relaxed

Warm topical local anaesthetic

Slow injection of injected local anaesthetic (puts less pressure on the nerves)

87
Q

What are the possible complications of skin surgery? (6)

A
  • Bleeding
  • Wound dehiscence (rupturing wound after it has been stitched up)
  • Infection
  • Scarring
  • Motor or sensory nerve damage
  • Loss of function e.g., damaged eyelid
88
Q

What are the 6 main methods of skin surgery?

A
  • Electrosurgery
  • Snip excision
  • Curettage
  • Shave excision
  • Punch biopsy
  • Elliptical excision
89
Q

What is electrosurgery used for? (2)

A
  • Haemostasis (electrocautery)

- Treatment of minor skin lesions e.g., skin tags

90
Q

Describe snip excision

A

The lesion is grasped with a hook and pulled upwards

Scissors or a scalpel are used to cut across the base of the lesion

91
Q

Describe curettage

A

Curette loop is used to slice off the skin lesion

Electrocautery is used to seal the wound by haemostasis

92
Q

State an advantage and a disadvantage of curettage

A

Adv - minimally invasive

Disadv - pathology specimen does not accurately record the margins of the tumour

93
Q

Describe shave excision

A

Needle-like tool is pushed under the lesion

Special razor blade is slid under the needle to slice off the skin

94
Q

What are the advantages and disadvantages of punch biopsy?

A

Adv:

  • Quick
  • Produces good wound edges

Disadv:

  • Difficult to judge depth so may take bone
  • Round holes don’t seal well
  • Pathology sample may be too small
95
Q

Why is elliptical excision better than a round hole?

A

An ellipse is neater to close as a round hole often causes wrinkles aka ‘dog ears’

96
Q

Describe the optimal dimensions for an elliptical excision

A

3x longer than wide

30 degree angle at both ends

97
Q

During excision, the scalpel should be held at a 45 degree angle. T/F?

A

False

The scalpel should be held at 90 degrees during excision to give vertical wound edges

98
Q

What is used to stop the bleeding after excision?

A

Electrocautery

99
Q

What is Mohs surgery?

A

A skin cancer technique where layers of cancer tissue are removed and examined under the microscope until all of the cancerous tissue has been removed