Skin Cancer Flashcards
skin is made up of what 3 layers?
- epidermis
- dermis
- hypodermis
what are the 4 layers of epidermis?
- stratum cornea
- stratum lucidum
- stratum spinous
- stratum basale
What are the 4 major types of skin cancer?
- Keratinocyte derived
eg basal cell carcinoma, squamous cell carcinoma
aka Non melanoma skin cancer (NMSC) - Melanocyte derived
eg Malignant melanoma - Vasculature derived
eg Kaposi’s sarcoma, angiosarcoma - Lymphocyte derived
eg Mycosis fungoides
skin cancer arises due to accumulation of genetic _____ –> which causes it to ______ in a uncontrolled manner
skin cancer arises due to accumulation of genetic mutation –> which causes it to proliferate in an uncontrolled manner
What are some causes of skin cancer?
give examples of each cancer derived from each cause/.
- Genetic syndromes
Gorlin’s syndrome
xeroderma pigmentosum - Viral infections
HHV8 in Kaposi’s sarcoma
HPV in SCC - UV light (most common cause)
BCC, SCC, malignant melanoma - Immunosuppression
drugs, HIV, old age, - leukaemia
Malignant melanoma = tends to be of higher prevalence in white ethnicity individuals
-
Basal cell carcinoma = increasing in incidence
what are they caused by?
sun exposure
Genetics
UVA –>has higher penetration
- major cause of skin aging
contributes to skin carcinogenesis
-
How doe UVB induce DNA Abnormalities of the skin?
- UVB directly induces abnormalities in SNA
- -> induces photoproducts
- -> affects pyramiding Cytosine + thymine ases
–> usually repaired quickly by nucleotide excision repair
What things can UV damage induce to DNA?
- cell division
- dna repair
- cell cycle arrest defect.
What mutations can cause skin cancer?
- Mutations that stimulate uncontrolled cell proliferation
Eg abolishing control of the normal cell cycle (p53 gene)
2/ Mutations that alter responses to growth stimulating / repressing factors
3.Mutations that inhibit programmed cell death (apoptosis)
what is sub burn?
Exposure to UV –> build up of mutations –> apoptosis of the keratinocyte occurs –> protects cells from becoming cancer cells.
UVA and UVB effect the expression of genes involved in skin immunity
–> Depletes / increases Langerhans cells in the epidermis
UVA and UVB effect the expression of genes involved in skin immunity
–> Depletes / increases Langerhans cells in the epidermis
in exposure to UV, there will be a reduced immunocompetence + immunosurveillance
-
melanin is produced by
melanocytes within the basal layer of the epidermis
skin color depends on:
the amount and type of melanin produced
What are the 2 types of melanin formed?
Eumelanin – brown or black
Phaeomelanin – yellowish or reddish brown
—> Melanin is formed from tryosine via a series of enzymes
regulation of melanin type production is controlled by
MCR1 gene
define malignant melanoma
caused by:
Malignant tumour of melanocytes
- -> Melanocytes become abnormal
- -> Atypical cells and architecture
caused by:
UV exposure
Genetic factors
what is lentigo maligna
(Melanoma in situ)
- Proliferation of malignant melanocytes within the epidermis
- No risk of metastasis
- light / dark brown colors
- irregular shape
what is lentigo maligna melanoma
- there is superficial spreading MM
- Lateral proliferation of malignant melanocytes
- Invade basement membrane
- Risk of metastasis
How would you diagnose superficial spreading malignant melanoma?
ABCD rule
- Asymmetry
- Border irregular
- Colour variation (dark brown-black)
- Diameter >0.7mm and increasing
- Erythema
what is nodular malignant melanoma?
- grows downwards
- bad prognosis
- Vertical proliferation of malignant melanocytes
- risk of metastasis
–> sometimes accompanies with spreading melanoma as well
What is Acral lentiginous melanoma
- melanoma of palms / soles
what is Amelanotic melanoma
- no production of melanin at all
- often difficult to diagnose
What re the 5 main types of malignant melanoma?
Superficial spreading Nodular Lentigo maligna melanoma Acral lentiginous Amelanotic
How is melanoma prognosis determined
- breslow thickness
- measurement from granular layer to bottom of the tumour
What are main risk factors for the development of melanoma?
- family history
- UV radiation
- sunburns during childhood
- skin type I + II
- personal history of melanoma
- atypical/ dysplastic nevus syndrome
What is squamous cell carcinoma usually caused by?
Caused by UV exposure HPV Immunosuppression May occur in scars or scarring processes
Is there risk of metastasis in Squamous cell carcinoma?
- yes
What is SCC ?
Malignant tumour of keratinocytes
- may commonly occur on lips/ ears (high risk)
What is basal cell carcinoma?
Malignant tumour arising from basal layer of epidermis
- slow growing
- invades tissue but doesn’t metastasis
- common on face
- commonly arborising (like tree branches) telangiectasia
what is Epidermodysplasia veruciformis?
(tree man)
Rare autosomal recessive condition
–> predisposition to HPV
–> induced warts and SCCs
What is Kaposi’s sarcoma
tumor of endothelial cells of the lymphatics
- purple nodules on skin
- associated with HIV / HHV8
what is the main treatment for these skin cancers ?
- surgical
