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Cancer > Skin cancer > Flashcards

Skin cancer Flashcards

1
Q

Skin microanatomy

A

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2
Q

Structure of the epidermis

A

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3
Q

Types of skin cancer

A
  • Keratinocyte derived (eg: BCC, SCC)
  • Melanocyte derived (eg: malignant melanoma)
  • Vasculature derived (eg: Kaposi’s sarcoma)
  • Lymphocyte derived (eg: mycosis fungoides)
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4
Q

Causes of skin cancer

A

ACCUMULATION OF GENETIC MUTATIONS LEADS TO UNCONTROLLED CELL PROLIFERATION

  • Genetic syndromes (Gorlin’s syndrome)
  • Viral infections (HHV8 in Kaposi’s sarcoma)
  • UV light (BCC,SCC)
  • Immunosuppression (drugs, HIV etc)
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5
Q

Malignant melanoma

A

MALIGNANT TUMOUR OF MELANOCYTES

  • melanocytes become abnormal
  • atypical cells and architecture
  • risk of metastasis

Causes:

  • UV exposure
  • genetic factors
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6
Q

UV spectrum

A

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7
Q

UVB

A
  • most important wavelength in skin carcinogenesis
  • directly induces DNA abnormalities
  • induces photoproducts
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8
Q

UVA

A
  • 100x more UVA penetrates Earth surface than UVB
  • major cause of skin ageing
  • skin carcinogenesis contribution
  • used therapeutically in PUVA therapy
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9
Q

UV induced skin carcinogenesis

A

-UV damage to DNA leads to mutations in specific genes (cell division, DNA repair, cell cycle arrest)

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10
Q

Repair of UV induced DNA damage

A
  • photoproducts removed by nucleotide excision repair

- xeroderma pigmentosum=genetic condition with defective nucleotide excision repair

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11
Q

Mutations causing cancer

A
  • mutations stimulating uncontrolled cell proliferation
  • mutations altering responses to growth stimulating/repressing factors
  • mutations that inhibit apoptosis
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12
Q

Sunburn

A
  • UV light leads to keratinocyte cell apoptosis
  • ‘sunburn’ cells are apoptotic cells in UV overexposed skin
  • apoptosis removes UV damaged cells in skin which might otherwise become cancer cells
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13
Q

Photocarcinogenesis

A

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14
Q

Immunomodulatory effects of UV light

A
  • UVA and UVB effect gene expression in skin immunity (deplete Langerhans cells in epidermis)
  • reduced skin immunocompetence and immunosurveillance (UV phototherapy basis) but further increases cancer causing potential of sun exposure
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15
Q

Fitzpatrick phototypes

A

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=moderate constitutive pigmentation (afrocaribbean)

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16
Q

Melanin

A
  • melanin pigmentation responsible for skin colour=dependent on amount and type of melanin produced, not melanocyte density (fairly constant density)
  • produced by melanocytes within basal layer of epidermis
  • dictates skin sensitivity to UV damage
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17
Q

Types of melanin

A

MELANIN FORMED FROM TYROSINE VIA ENZYME SERIES

  • Eumelanin=brown or black
  • Phaeomelanin=yellowish or reddish brown
18
Q

MCR1 gene

A
  • > 20 polymorphisms
  • variation in eumelanin:phaeomelanin produced
  • explains different hair colour and skin types
19
Q

Lentigo maligna

A
  • ‘in situ melanoma’
  • proliferation of malignant melanocytes within epidermis
  • no risk of metastasis

Features:

  • irregular shape
  • light and dark brown colours
  • size usually >2 cm
20
Q

Superficial spreading malignant melanoma

A
  • lateral proliferation of malignant melanocytes
  • invade basement membrane
  • risk of metastasis
21
Q

Superficial spreading malignant melanoma diagnosis

A 
ABCD rule
A=asymmetry
B=border irregular
C=colour variation (dark brown-black)
D= >0.7mm diameter and increasing
E=erythema
22
Q

Nodular malignant melanoma

A
  • vertical proliferation of malignant melanocytes with no previous horizontal growth
  • risk of metastasis
  • much darker appearance
23
Q

Nodular melanoma arising with superficial spreading melanoma

A
  • downward proliferation of malignant melanocytes following previous horizontal growth
  • nodule developing within irregular plaque
  • prognosis worsens
24
Q

Acral lentiginous melanoma

A

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25
Q

Amelanotic melanoma

A

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26
Q

Types of malignant melanoma

A
  • superficial spreading
  • nodular
  • lentigo maligna melanoma
  • acral lentiginous
  • amelanotic
27
Q

Breslow thickness

A
  • measurement from granular layer to bottom of tumour

- used for melanoma prognosis

28
Q

Risk factors for melanoma development

A
  • family history of dysplastic nevi or melanoma
  • UV irradiation
  • sunburns during childhood
  • intermittent burning exposure in unacclimatised fair skin
  • atypical/dysplastic nevus syndrome
  • personal melanoma history
  • skin types 1,2
29
Q

Squamous cell carcinoma (SCC)

A
  • malignant tumour of keratinocytes
  • risk of metastasis

Causes:

  • UV exposure
  • HPV
  • Immunosuppression
  • scars or scarring processes
30
Q

Basal cell carcinoma (BCC)

A
  • malignant tumour arising from basal layer of epidermis
  • slow growing
  • invades tissue but does not metastasise
  • common on face
  • can be nodular of superficial

Causes:

  • Sun exposure
  • Genetics
31
Q

Mycosis fungoides

A

/

32
Q

Kaposi’s sarcoma

A

-HIV and HHV8 associated

33
Q

Epidermodysplasia verruciformis

A
  • ‘treeman syndrome’
  • rare autosomal recessive condition
  • gives predisposition to HPV-induced warts and SCC
34
Q

Importance of sunlight

A
  • essential for photosynthesis (plants)
  • infrared spectra provide warmth
  • effect on human mood
  • stimulates vitamin D production in skin
35
Q

Photoproducts induced by UVB

A
  • affects pyrimidines (cytosine and thymine bases)
  • cyclobutane pyrimidine dimers
  • 6-4 pyrimidone photoproducts
  • usually quick repair by nucleotide excision repair
36
Q

Skin carcinogenesis and UVA

A
  • UVA promotes skin carcinogenesis
  • DNA forming cyclobutane pyrimidine dimers but less efficiently than with UVB
  • free radicals damage DNA and cell membrane
37
Q

Host response to UV light

A

Determined by genetic influences (especially skin phototype)

38
Q

Malignant melanoma incidence

A

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39
Q

Basal cell carcinoma incidence

A

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40
Q

Melanoma recognition

A

A=asymmetry
B=border
C=colour
D=diameter

Cancer (15 decks)

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