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Year 2 MCD Cancer > 15: Skin Cancer > Flashcards

15: Skin Cancer Flashcards

1
Q

Recall the gross anatomy of the skin

A
  1. Epidermis
  2. Dermis
    1. separated by BM
  3. Hypodermis
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2
Q

What are the differnet skin cancers that are derived from keratinoytes?

A

Overall called: Non-melanoma skin cancer

  1. Squamous Cell Carcinoma (SCC)
  2. Basal Cell Carcinoma (BCC)
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3
Q

What kind of cancer is Melanocyte derived?

A

Malignant Melanoma

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4
Q

Which types of skin cancers are vasculature derived?

A

Overall: rare

  • Kaposi’s sarcoma, associated with HIV and HHV8
  • angiosarcoma
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5
Q

Name a skin cancer that is lymphocyte derived

A

Mycosis fungoides

cutaneous T-cell lymphoma

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6
Q

Name different causes for skin cancer

A
  1. Genetic mutations
    1. Gorlin’s syndrome
      1. increases the risk of basal cell carcinoma
    2. xeroderma pigmentosum
      1. mutation in DNA mismatch repair
  2. Viral infections
    1. HHV8 in Kaposi’s syndrome
    2. HPV in SCC
  3. UV light
  4. Immunosupression
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7
Q

What is the trend of the incidence of Malignantn melanoma?

A

It is increasing in the past years

  • expecially in white people (small change in other ethnicities)
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8
Q

Explain the trend of the incidence of Basal cell carcinoma

A

Also increasing incidence

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9
Q

Differentiate between the different types of UV light

A
  1. UVA
    • 100x higher exposure than UVB
    • contributes to skin ageing
    • might contribute to carcinogenesis
    • but also exploited therapeutically because of immunosupressant effects
  2. UVB
    • causes Cancer (most important in carcinogenesis)
  3. UVC
    1. absorbed in athmosphere
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10
Q

Explain how UVB radiation causes cancer

A
  • Radiation directly causes mutations
    • causes formation of base dimers (thymine or cytosine dimers)
  • Normally repaired by nucleotide excision repair
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11
Q

Explain how UVA radiation might cause cancer

A

Also promotes skin cancer by

  • formation of pyrimidine dimers (but less potentn than UVB)
  • formation of free radicals
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12
Q

What kind of mutatins can cause skin cancer?

A
  1. Mutations that stimmulate uncontrolled proliferation
    • P53 mutation leading to abolished control of normal cell cycle
  2. Mutations that alter responses to growth factors/stimmulation
  3. Mutation interferin with apoptosis
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13
Q

Explain the effect of sunburn on the skin

A

Sunburn causes Keratinocyte apoptosis –> release of inflammatory mediators

–> inflammation of the dermis

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14
Q

What are the possible outcomes to photodamaged cells?

A
  1. Apoptosis (e.g. in sunburn)
  2. DNA repair
  3. Carcinogenesis
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15
Q

Explain the effect of UV light on the immune system

A

Influence immunity (UV ligh supresses immmune system)

  • Via:Change of immunoregulatory genes in epidermis
    • Depleting Langerhans cells in the epidermis
  • reduce immunocompetence and surveilance
    • used therapeutically e.g. in psoriasis (schuppenflechte)

–> Further increase in cancer risk

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16
Q

What does the host response to UV light depend on?

A

Depeinging on different genetic influences, expecially skin phototype

17
Q

Where do melanocytes sit?

What do they do?

A

They ususally sit at the basement membrane in the epidermis

  • produce melanin as reaction to UV light exposure
18
Q

Explain the production of Melanin

A

UV light exposure causes paracrine signaling from keratinocytes to melanocytes:

  • They produce Melainin
    • From tyrosine via a series of enzymes
  • Accumulates intracellularly in the Keratinocytes to protect the nucleus
19
Q

What are the different types of Melanin?

What determines which type you produce?

A
  • Eumelanin – brown or black
  • Phaeomelanin – yellowish or reddish brown

Dependant on present polymorphism on MCR1 gene

20
Q

What are the ususal causes and risk factors of malignant melanomas?

A

Causes:

  • UV exposure
  • Genetic factors

Risk factors:

  • family history
  • personal history
  • light skin type
  • UV radiation
  • sunburn durign childhood (burning is more critical than increased exposure to sun
21
Q

What is the prognosis of someone with malignant melanoma?

A

Depending on the stage of the disease and spreading

  • measurement of granular layer to bottom of layer
    • <1mm: thin
    • 1-4 intermediate
    • >4mm thick

but overall:

possibility of metastasis

22
Q

What is a Lentigo maligna?

How would it usually look like?

A

A melanoma in situ

  • proliferation of melanocytes within the epidermis
  • non-invasive –> no risk of metastisis

Presentation

  • Irregular shape
  • Light & dark brown colours
  • Size usually >2.0 cm
23
Q

How do you call an invasive form of a Lentigo Maligna?

A

Lentigo Maligna Melanoma

24
Q

What are the characteristics of superficial spreading malignant melanoma?

A
  • Lateral proliferation of malignant melanocytes
  • Invade basement membrane
  • Risk of metastasis

Can be diagnosed via ABCD(E)

  1. Asymmetry
  2. Border irregular
  3. Colour variation (dark, brown)
  4. Diameter >0.7mm and increasing
  5. Erythema
25
Q

What are the characteristics of a nodular malignant melanoma?

A

•Vertical proliferation of malignant melanocytes

(no previous horizontal growth)

Risk of metastasis –> worst prognosis and most agressive form of melanoma

26
Q

Name different types of malignant melanomas

A
  1. Lentigo Maligna (Melanoma
  2. Superficial spreading
  3. Nodular Melanoma
  4. Acral lentiginous
    1. slow horizontal growth
    2. often below feet
  5. Amelanotic
    1. no pigmentatin
27
Q

What are different causes of Squamous cell carcinoma?

A
  • UV exposure
  • HPV
  • Immunosuppression
  • May occur in scars or scarring processes
28
Q

What are squamous cell carcinomas?

What is its prognosis?

A

Malignant tumors of Keratinocytes

They might metastisis but lower risk than in melanomas

29
Q

What are common sites for Squamous cell carcinomas to occur?

A

They commonly occur on

  • generally sun-exposed skin
    • lips (worsening with smoking)
    • ears (expecially in men)
    • and legs of women
30
Q

What is a basal cell carcinoma?

What are its chracteristics, causes and usuall sites of occurence?

A
  • Malignant tumour arising from basal layer of epidermis
    • Caused
      • sun exposure
      • Genetics
  • Characteristics
    • Slow growing
    • Invades tissue, but does not metastasise
  • Common on face
  • offen appear “parly”: greyish, red colour with shiny and dialated capillary vessels on top
31
Q

What is mycosis fungoidis?

A

It is a cutaneous T-cell lymphoma

  • chronic disease, slow progression
32
Q

What is a Kaposi’s sarcoma?

A

Cancer of the endothelial cells of lymphatics

Associated with infections of HIV (AIDS) and HHV8 (Human Herpes Virus 8)

  • Form: nodules, plaques and flat lesions
33
Q

What is Epidermodysplasia veruciformis?

A

Rare autosomal recessive condition predisposition to HPV induced warts and SCCs

34
Q

What is the role of HPV in the development of SCC?

A

HPV infection is associated with increase in

  • cervical cancers
  • and caners in the head and neck region
    • In squamous cell carcinomas (e.g. oral scc)

Year 2 MCD Cancer (17 decks)

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