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
Merkel Cells

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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
a. Keratinocyte derived  
Basal Cell Carcinoma 
Squamous Cell Carcinoma 
b. Melanocyte derived  
Malignant Melanoma 
c. Vasculature derived 
Kaposi Sarcoma – endothelium of lymphatics  
Angiosarcoma – endothelium of blood vessels 
d. 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 that can lead to skin cancer?

A

HHV8

HIV

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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

UVA – reaches dead sea leve

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7
Q

How does UVB cause mutations in DNA?

A

Induces the formation of photoproducts
Particularly affects pyrimidines – causing cross-linking
Formation of cyclobutane pyrimidine dimers and 6-4 pyrimidine pyrimidone photoproducts

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8
Q

How are these 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 and 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

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16
Q

Where are melanocytes found within the epidermis?

A

In the basal layer

17
Q

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

A

It is packaged into melanosomes and it passes along the processes 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

18
Q

What are the two types of melanin?

A

Eumelanin – black/brown

Phaeomelanin – yellowish or reddish-brown

19
Q

What is melanin formed from?

A

Tyrosine

20
Q

What gene regulates the relative amounts of melanin produced?

A

MC1R

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
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

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)

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 theepidermis

35
Q

Describe the appearance of BCCs

A

They are pearly, have a rolled edge and often have arborising telangiectasia

36
Q

Name a cutaneous T cell lymphoma.

A

Mycosis fungoides

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