Skin cancer Flashcards
what are the risk factors for skin cancer (4)
sun exposure
age
genetics
immunosuppression
how does UVA increase risk of skin cancer
indirect oxidative damage
how does UVB increase risk of skin cancer
direct DNA damage
what genetic influences are there on skin cancer (3)
albinism
xeroderma pigmentation
naevoid basal cell carcinoma syndrome
what is albinism
do not produce melanin
what function does melanin have in preventing skin cancer
protects DNA in the basal layer form sun exposure
what causes xeroderma pigmentation
abnormal XP genes
why are XP (xeroderma pigmentation) genes important in preventing skin cancer
XP (xeroderma pigmentation) genes are needed to repair DNA damaged by sunlight
what is naevoid basal cell carcinoma syndrome
familial increased likelihood of cancer
what causes of immunosuppression increase skin cancer risk (3)
immunosuppressive drugs
autoimmune conditions (eg crohns)
organ transplant
how does skin cancer present in post organ transplant (immunosuppressed) patients
‘transplant hands’ = changes to hands may be malignant
which type of skin cancer is malignant
melanoma
what are the 2 type of non-melanoma skin cancer
basal cell carcinoma (BCC)
squamous cell carcinoma (SCC)
what is an oncogene
an overactive form of a gene = regulates cell division, can be switched off but not switched off
what is the difference between a proto-oncogene and an oncogene
a proto-oncogene can be switched on and off, an oncogene can only be switched on
UVB causes direct DNA damage, what happens to the damaged DNA
what happens if this doesnt occur
NER (nucleotide excision repair) recognises damaged DNA and ‘fills it in’
if this doesnt occur = damaged DNA is replicated = mutations arise
what base change usually occurs in the damaging of DNA by UVB
TT to CC
UVA causes indirect damage via what mechanism
oxidation of DNA bases
how are oxidised DNA bases usually repaired
by base excision repair (BER)
which base change usually occurs in the damaging of DNA by UVA
C to A
are melanomas more or less common than non-melanoma skin cancers
less
are melanomas more or less serious than non-melanoma skin cancers
more
are melanomas more common in young or elderly
young
are melanomas more common in males or females
females
what skin types are a risk factor for melanoma
skin type I/II
what are the 4 types of melanoma
superficial melanoma (SSM)
acral/mucosal lentiginous melanoma (A/MLM)
lentigo maligna melanoma (LMN)
nodular melanoma
which type of melanoma is most common
superficial melanoma
where do superficial melanomas present
trunk/limbs
what is the general pathophysiology of melanomas (growth phases and presentation)
radial growth phase (RGP) = present as macules
vertical growth phase (VGP) = invade and mitose in the dermis = present as lumps
in which growth phase can melanomas metastasise
vertical growth phase
what differs in the pathophysiology of nodular melanomas to the other melanomas
there is no horizontal growth phase
what differs in the presentation of nodular melanomas to the other melanomas
they dont present as macules, just as nodules
what differentiates a melanoma from a non-melanoma skin cancer (BCC or SCC)
ABCDE Asymmetry Border (irregular) Colour (>2) Diameter (>6mm) Evolution (changing)
what is the treatment of malignant melanomas
elliptical excision biopsy followed by further surgery/radiotherapy/chemo
what is the pharmacological treatment of malignant melanoma (eg if surgery is contraindicated)
drugs to prevent cell growth
drugs that activate T cells to enable tumour cell killing
which drugs prevent cell growth in malignant melanomas
end in -nib
think - you want to ‘nip it in the bud’
which drugs activate T cells to enable tumour cell killing in malignant melanomas
end in -umab
what are the signs of poor prognosis in malignant melanomas (4)
ulceration
lymph involvement metastasis
tumour depth (Breslow thickness >4mm)
how is Breslow thickness measured for the prognosis of malignant melanomas
granular layer to deepest part of tumour
a Breslow thickness of
<1mm
a Breslow thickness of >?mm in a malignant melanoma has a poor prognosis (50% 5 year survival)
> 4mm
how long does it take a malignant melanoma to be >4mm deep (Breslow thickness)
6 months
is a basal cell carcinoma malignant or not
no
where does a basal cell carcinoma arise from
keratinocytes in the basal layer of the epidermis
what % of non-melanoma skin cancers are basal cell carcinomas
75
are basal cell carcinomas fast or slow growing
slow growing (take years)
what genetic mutation causes basal cell carcinomas
PTCH1 mutation
what signalling pathway does a PTCH1 cause in basal cell carcinomas
hedgehog signalling pathway = causes cell proliferation
what are the 3 types of basal cell carcinoma
nodular
superficial
infiltrative
how does a nodular basal cell carcinoma present (3+location)
pearly colour
raised lesion
rodent ulcer
location - usually on face, head, neck
how does a superficial basal cell carcinoma present (+location)
pink/red patch ( looks like eczema but wont go away with cream!)
crusted
location - usually trunk, shoulders
how would you differentiate between eczema and a superficial basal cell carcinoma
eczema will go away with cream (emollients etc)
how would you treat a superficial basal cell carcinoma
extensive surgery
how does a infiltrative basal cell carcinoma present (+location)
waxy, scaly plaque
thickened skin
location - usually in middle of face
what is the treatment for basal cell carcinoma (4)
vismodegib (blocks hedgehog signalling pathway = prevents proliferation)
radiotherapy
5% imiquimod cream
mohs surgery - if superficial
what is mohs surgery
when the skin is biopsied throughout the surgery so that only cancerous cells are being removed
what is the prognosis for basal cell carcinoma (good/bad)
good if treated
is squamous cell carcinoma a type of melanoma
no
where does squamous cell carcinoma arise from
keratinocytes in the epidermis (anywhere in epidermis)
are squamous cell carcinomas fast or slow growing
fast growing (take months)
where do squamous cell carcinomas arise
sun damaged skin (eg face, ears, hands)
what are the precancerous lesions associated with squamous cell carcinomas (not BCCs) (2)
actinic keratosis
bowens disease
what is the treatment of precancerous squamous cell carcinoma lesions
cryotherapy
NOT surgery
where do actinic keratosis typically present
head/neck
how does actinic keratosis present (not the same as actinic lenitigines)
thick, crusty or scaly skin
red
which precancerous squamous cell carcinoma lesion presents on the shins of females as a red and scaly plaque
bowens disease
where does bowens disease usually present
on the skins of females
how does bowens disease present
red and scaly plaque
non pigmented
how does bowens disease look on histology
full thickness dysplasia of keratinocytes
if a patient present with a ‘horn’, what type of skin cancer do they have
why
squamous cell carcinoma
a ‘horn’ is keratinised (not BCC as they only have keratinocytes from basal layer, SCC have keratinocytes from everywhere in epidermis)
is it worrying if a squamous cell carcinoma bleeds
no, treated the same as any other squamous cell carcinoma, same prognosis
how are squamous cell carcinomas treated (2)
elliptical excision biopsy
5% imiquimod cream
are squamous cell carcinomas more or less likely to spread than basal cell carcinomas
where do they spread to/via
more likely - can spread along nerves and cause a new tumour growth just along from the original tumour site
is the prognosis of non-melanoma skin cancers (SCC and BCC) better or worse than melanomas
much better, 0.5% death rate
is a benign seborrheic keratosis (aka seborrheic wart, basal cell papilloma) benign or malignant
benign tumour, will not metastasise
how does a benign seborrheic wart present (5)
stuck on appearance warty surface well defined keratin pearls greasy appearance
do benign seborrheic warts present in the young or elderly
elderly
is a merkel cell carcinoma serious
yes, needs removal
which type of non melanoma skin cancer presents as ‘picket fence’ around cells on histology
nodular basal cell carcinoma
what is another name for a benign seborrheic wart
basal cell papilloma
which type of cancer looks as if it is ‘stuck on’
basal cell papilloma (seborrheic wart)
which type of cancer has ‘horn cysts’ on histology
basal cell papilloma (seborrheic wart)
