UV - Photoaging and Cancer Flashcards
what UV cant pass through window glass
UVB
what are the theraputic qualities of UV light
anti inflammatory
immunosuppressive
antiproliferative
apoptotic
what are acute skin effects of UV radiation
erythema (sunburn)
immune suppression
what is vit D soluble in
fat
what metabolism is vitamin D essential for
calcium and phosphorous metabolism
what is the major role of vitamin D
increases the flow of calcium into the blood stream by promoting absorption from food in the intestines, re absorption of calcium in the kidneys- allows mineralisation of bone
what makes up vitamin D
fat soluble vitamins: vit D2, vit D3, calcitriol
what is calcitriol and what does it do
is the biologically active hormonal form of vitamin D- used by the body to form and maintain healthy strong bones
what is the result of vit D deficiency in children
rickets
what is the result of vit D deficiency in adults
osteomalacia (muscular weakness, bone pain and bone fractures)
long term osteoperosis
how much sunlight should you get a day
15-20mins
if high risk of skin cancer less/ get vit D from diet
what groups of people are at risk of getting vit D deficiency
darked skin people, photosensitive people, premature babies, bad diet, vegans/vegetarians, lack of sunlight, eldery, eating disorders, people who cover up for religion, people with malabsorption/ bowel problems
how can you confirm suspected vit D deficiency
measure serum vit D
also can measure calcium and phosphate
what is the management for vit D deficiency
vit D, calcium and phosphate supplements
advise lifestyle changes
what are the steps of carcinogenesis
initiation (clonal expansion in single cell)
promotion (cell proliferation and angiogenesis)
progression
transformation (multiple changes in growth regulation resulting in de-differentiation, autonomous growth, invasive behaviour)
how does skin protect itself from UV damage
producing melanin and thickening
DNA repair mechanisms or killing damaged cells (apoptosis)
what are the 6 sequences leading to a non melanoma skin cancer
- epidermal keratinocyte DNA damage by UV
- mutation of tumour suppressor genes and loss of apoptotic function
- mutation of proto-oncogenes
- colonal selection of non-apoptosing mutated cells
- UV suppresses normal cell mediated immune response against tumour cells
- grows into tumour
why are MM the most serious form of skin cancer
metastasise early
how do BCC cause damage
local invasion rather than metastasis
describe what as nodular basal cell carcinoma looks like as it progresses
initially reddish, dome shaped with translucent surface and dilated surface capillaries
as it expands, centre may show necrosis and ulceration leaving rolled edge
describe the appearance of a superficial BCC
flat and expands gradually, red, scaly, with a slight raised whipcord’ margin
what non MM cancer is associated with intermittent ‘burning’ episodes
basal cell
what non MM cancer is associated with life long exposure to sun
Squamous cell carcinoma
what cells do squamous cell carcinomas arise from
keratinocytes
how does an SCC usually present
scaly expanding and ulcerating nodule
do SCC’s usually metastasise
no
what pre malignant lesions predispose to SCC
actinic keratoses
bowen’s disease
what is bowens disease
epidermal carcinoma in situ
what are the stages of melanocytic naevi
junctional
compound
intradermal
what is a junctional melanocytic naevi
naevus cells in dermoepidermal junction
tend to be flat/ slighlty elevated with smooth surface and uniform pigmentation
what is a compound melanocytic naevi
naevus cells at dermoepidermal junction and upper dermis
lesions slightly elevated or dome shaped, often pigmented
hairs may project from surface
what is an intradermal melanocytic naevi
naevus cells in dermis
dome shaped, verrucous (warty)
pedunculated or sessile
often flesh coloured occasionally hairy and may display surface telangiectasia
what are features of benign pigmented lesions
well defined margin, even pigmentation, symmetrical, not changing/ changing very slowly
what are the clinical features of MM
asymmetry border irregular multiple colours diameter >6mm history of increasing size/ changing shape
what is involved in the normal process of skin aging
skin thins lose elastic and collagen fibres subcutaneous fat is lost fine wrinkles develop number of hair follicles, sweat and sebaceous glands decreases skin drys
what are the features of photoaging
solar elatosis- skin coarse and yellow, looses elasticity quickly
irregular pigmentation, freckling, lentigo
telangiectasia and atrophy, easy bruising
roughness and dryness
deep wrinkling
what therapeutic effects does UV radiation have in psoriasis and dermatitis
anti inflammatory
immunosuppressive
antiproliferative
apoptotic
what is PUVA
psoralen + UVA
what UV is used for phototherapy
narrowband UVB
sunbeds are classified as a carcinogen in the same category as tobacco true/ false?
true
