skin cancer Flashcards
DIAGRAM microanatomy of skin
epidermis, dermis, and hypodermis
DIAGRAM structure of epidermis+ cells involved in cancer
stratum corneum, lucidum, spinosum and basale- keratinocytes are in all layers and are shed in corneum, melanocytes are present in basala
types of skin cancer with examples
keratinocyte derived eg basal cell/squamous cell carcinoma- melanocyte derived eg malignant melanoma- vasculature derive eg kaposi’s/angiosarcoma- lymphocyte derived eg mycosis fungoides
causes of skin cancer
genetic syndromes eg gorlins syndrome/xeroderma pigmentosum, viral infections eg herpes for kaposis, HPV in SCC, UV LIGHT (BCC, SCC, melanoma), and immunsurpression (eg HIV)
who does malignant melanoma affect
has increased in WHITE ppl, not in other ppl
which part of UK is melanoma most present
south of england (ie most sunlight)
what types of UV radiation cause skin cancer
UVB and UVA, NOT UVC (blocked)- UVB most carcinogenic, but UVA penetrates deeper
what mutation does UVb and a radiation cause
b produces photoproducts called thymine dimers, a does as well, but also free radicals
bodys response to thymine dimers
removed by NUCLEOTIDE EXCISION REPAIR
what is the defect in xeroderma pigmentosum
defective nucleotide excision repair
what occurs in sunburn
UV causes keratinocyte cell apoptosis (otherwise may become cancer cells)
difference in appearance between melanoma vs BCC
black vs pinkish in colour
pathophysiology of skin cancer by UV
UV causes DNA damage, and if there’s a p53 mutation, leads to skin cancer- UV cells deplete langerhan cells (APCs) too in epidermis= further risk
immune effects of UV light+ clinical signficance
depletes langerhan cells raises risk of skin cancer, BUT good for inflammatory conditions like psoriasi
phototypes of skin+ significance
6 phototypes, from always burns never tans (ie white, most likely to get melanoma), to more likely to tan (brown), to afrocarribbean (never burn)
melanin-what produced by, and what skin colour depends on
produces colour, produced by melanocytes- colour depends on amount of melanin, NOT amount of melanocytes ie afrocarribeans produce more melanin
protective effect of melanin
keratinocytes produce MSH- melanocytes produce melanin, and keratinocytes place it around their nuclei to protect them, called MELANOSOMES- leads to tanning
types of melanin and gene controlling it
eumelanin (brown/black) or phaeomelanin (red-brown)- determined by mutations in MCR1 gene
what a.a is melanin derived from
tyrosine
lentigo maligna ie in situ and appearance
malignant melanocytes proliferate in epidermis (should be in basale)- but NO RISK of metastasis- FLAT and DARK PATCH
DIAGRAM superficial spread malignant melanoma- difference from lentigo maligna
melanocytes proliferate not just in epidermis, but downwards ie invade basement membrane= risk of metastasis- also LATERAL spread
DIAGRAM nodular malignant melanoma
DOWNWARDS proliferation of melanocytes= metastasis
nodular and superficial spreading
both- downwards proliferation with lateral spreading as well
acral lentiginous melanoma- location
occur in palms or soles of feet
amelanotic melanoma
non-pigmented
diagnosing melanoma
ABCD- asymmetry, irregular BORDER, black COLOUR, above 0.7mm DIAMETER
determining prognosis of melanoma
BRESLOW thickness- ie how deep from epidermis to bottom of tumour
risk factors for melanoma
skin type 1/11, family history of melanoma
keratoacanthoma- key feature and metastasis?
type of SCC of KERATINOCYTES- often have a white keratin HORN- risk of metastasis
BCC- metastasis? where most common
arises from stratum BASALE (unlike SCC)- no metastasis, mostly on face
mycosis fungoides
lymphoma of skin- looks like psoriasis
kaposis sarcoma- cause
tumour coming from endothelial cells of lymph vessels- associated with herpes (HHP8) and HIV
epidermodysplasia veruciformis+ cause
warts caused by HPV
