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Y2 Cancer (MCD) > Cancer as a Disease – Skin Cancer > Flashcards

Cancer as a Disease – Skin Cancer Flashcards

1
Q

What are the five layers of the epidermis?

A

Stratum corneum Stracum lucidum Stratum granulosum Stratum spinosum Stratum basale

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2
Q

What are the main cell types in the epidermis?

A

Keratinocytes Melanocyts Langerhans Cells (dendritic cells) Merkel Cells - sensation

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3
Q

State the types of skin cancer that come under each of the following types: a. Keratinocyte derived b. Melanocyte derived c. Vasculature derived d. Lymphocyte derived

A
  1. Keratinocyte derived
  • Basal Cell Carcinoma
  • Squamous Cell Carcinoma
  1. Melanocyte derived
    * Malignant Melanoma
  2. Vasculature derived
  • Kaposi Sarcoma – endothelium of lymphatics
  • Angiosarcoma – endothelium of blood vessels
  1. Lymphocyte derived
    * Mycosis fungoides
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4
Q

State two examples of genetic syndromes that massively increase the risk of getting skin cancer.

A
  • Gorlin’s Syndrome – regular BCCs
  • Xeroderma Pigmentosum – increased risk of BCC, SCC and malignant melanoma
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5
Q

Give two examples of viruses and the skin cancer they can lead to

A
  • HHV8 - Karposi’s sarcoma
  • HPV - SCC, especially in genitals and mouth
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6
Q

What is the difference between the depth reached by UVB radiation and UVA radiation?

A

UVB – reaches sea level, reach epidermis

UVA – reaches dead sea level (423m below sea level), reach dermis

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7
Q

How does UVB cause mutations in DNA?

A
  • Induces the formation of photoproducts
  • Particularly affects pyrimidines – causing cross-linkin
  • Formation of cyclobutane pyrimidine dimers (T=T, T=C, C=C)
  • and 6-4 pyrimidine pyrimidone photoproducts
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8
Q

How are UVB mutations usually corrected?

A

Nucleotide excision repair

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9
Q

How can UVA promote skin carcinogenesis?

A
  • Forms cyclobutane pyrimidine dimers (but less effectively than UVB)
  • Also generates free radicals that can damage DNA
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10
Q

Name a condition that is caused by a defect in nucleotide excision repair.

A

Xeroderma pigementosum

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11
Q

What are the features of this condition?

A
  • Increased risk of BCCs, SCCs and melanoma
  • Photosensitivity
  • Dry skin
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12
Q

What happens to keratinocytes in sunburn?

A
  • The UV damage leads to keratinocyte apoptosis
  • The apoptotic cells in UV overexposed skin are called sun burn cells
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13
Q

Describe the immunomodulatory effects of UV light.

A
  • UVA and UVB affect the expression of genes involved in skin immunity
  • It depletes Langerhans cells in the epidermis
  • This reduces skin immunocompetence and immunosurveillance
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14
Q

What are the consequences of UV therapy for psoriasis?

A
  • Increased risk of skin cancer UV can act on keratinocytes and cause DNA damage
  • If the Langerhans cells have been depleted then they will be unable to knock out the damaged cells so they could persist and become cancerous
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15
Q

Which system is used to categorise people based on their skin type and sensitivity to UV?

A

Fitzpatrick Phenotypes

I-VI with I being: always burns never tans, and VI being Afro-Caribbean skin tone

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16
Q

Where are melanocytes found within the epidermis?

A

In the basal layer

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17
Q

What happens to melanin once it is produced by the melanocytes?

A
  • It is packaged into melanosomes and it passes along the dendrites of the melanocytes and is taken up by the keratinocytes
  • The keratinocytes put the melanosomes around their nuclei, which protects the nuclei from DNA damage
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18
Q

What are the two types of melanin?

A
  • Eumelanin – black/brown
  • Phaeomelanin – yellowish or reddish-brown
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19
Q

What is melanin formed from?

A

Tyrosine

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20
Q

What gene regulates the relative amounts of melanin produced?

A
  • MC1R
  • Over 20 polymorphisms that vary in the eumelanin:phaeomelanin production ratio
21
Q

What is Lentigo Maligna?

A
  • Proliferation of malignant melanocytes within the epidermis
  • There is no risk of metastasis
  • This is also called melanoma in situ
22
Q

What is it the name given to a large area of lentigo maligna that has a smaller area within it that has become invasive?

A

Lentigo maligna melanoma

23
Q

What is a superficial spreading malignant melanoma?

A
  • Lateral proliferation of malignant melanocytes
  • They invade the basement membrane so there is a risk of metastasis
24
Q

What is the ABCDE for the diagnosis of superficial spreading malignant melanoma?

A
  • Asymmetry
  • Border irregularity
  • Colour variation
  • Diameter (>0.7 mm and increasing)
  • Erythema - redness indicating loss of differentiation and keratin production
25
Q

What is it called when a pale area appears in the middle of a melanoma?

A

Area of regression – this is associated with higher risk of metastasis

26
Q

What is it called when you get a vertical proliferation of malignant melanocytes?

A

Nodular malignant melanoma

Associated with high risk of metastasis

27
Q

Describe the pattern of growth when a nodular melanoma arises from a superficial spreading malignant melanoma.

A

Downward proliferation of malignant melanocytes that is following previous horizontal growth

28
Q

What is the type of melanoma that occurs on the palms and soles?

A

Acral lentiginous melanoma

29
Q

What type of melanoma produced no melanin?

A

Amelanotic melanoma

30
Q

What is the prognosis of melanoma based on?

A

Breslow thickness – thickness from the top of the tumour to the bottom

31
Q

What is a keratoacanthoma?

A
  • It is either a benign lesion or a benign version of an SCC
  • It grows rapidly but then disappears
  • There is no risk of metastasis
32
Q

What can squamous cell carcinomas (SCCs) be caused by?

A
  • UV exposure
  • HPV
  • Immunosuppression (main cancer in organ transplant patients)
  • May occur in scars or scarring processes
33
Q

How can you tell whether an SCC is well differentiated?

A

If the lesion has a keratin horn then it shows that the keratinocytes can still produce keratin and so they are well differentiated

34
Q

What is a basal cell carcinoma (BCC)?

A

Malignant tumour arising from keratinocytes in the basal layer of the epidermis

35
Q

Describe the appearance of BCCs

A
  • They are pearly
  • They have a rolled edge
  • They often have arborising telangiectasia - vessel pattern like a tree
36
Q

Name a cutaneous T cell lymphoma.

A

Mycosis fungoides

Atypical lymphocytes invade the dermis and epidermis

Slowly progressive

37
Q

Which viruses are associated with Kaposi sarcoma?

A
  • HHV8
  • HIV
38
Q

Name a disease that predisposes to SCCs and HPV induced warts (that can become incredibly keratotic).

A

Epidermodysplasia Veruciformis

39
Q

What are the most common skin cancers?

A

Keratinocyte derived

BCC - most common

SCC - 2nd most common

40
Q

What are the most common causes of skin cancer?

A

UV light - most common

Genetic syndromes

Viral infections

Immunosupression

41
Q

What areas have high risk of metastasis?

A

Ears, lips, genitals

42
Q

Which genes does UV damage lead to mutations in

A
  • Cell division
  • DNA repair
  • Cell cycle arrest
43
Q

What is UV light immunotherapy used to treat?

A

Psorasis

44
Q

How is melanin production stimulated?

A

Keratinocytes release MSH which triggers melanocytes to produce more melanin

45
Q

What are the features of lentigo malign?

A
  • Irregular shape
  • Light and dark brown colour
  • Flat
  • Usually occur on face and head
46
Q

What are the different types of malignant melanoma?

A
  • Superficial spreading
  • Nodular
  • Lentigo maligna melanoma
  • Acral lentiginous
  • Amelanotic
47
Q

What is a SCC?

A

Squamous cell carcinoma

Risk of metastasis

48
Q

What are the invasive features of BCCs?

A
  • Slow growing
  • Invade tissue
  • Never metastesise
49
Q

What are BCCs caused by?

A
  • Sun exposure
  • Genetics

Y2 Cancer (MCD) (16 decks)

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