cancer 15: skin cancer Flashcards
Where does most skin cancer rise (describe microanatomy)
Epidermis
4 cell types-keratynocytes, melanocytes, (most important for cancer)
Dendritic cells and merkey cells
differentiate up from basale-(where melabocytes are) and flatten/lose nucleus as reach top
Very close to UV
What cells can lead to skin cancer?
Keratinocye derives-basal cell or squamous
Melanocyte dervied
vasculature derived
Lymphocte derived
What are some causes of skin cancer?
genetic syndromes-predisposition
eg: Gorlins syndrome-basal cell
Xeroderma Pigmentosum-cant repair DNA-multiple skin cancer
Viral infections-HHV* (herpes)0=-kaposi
HPV-sqamous cell cancer
UV radiation-BCC/SCC/malignant melanomas
immunosupressants-drugs, HIV, old age, leukemia
Epidiemology of malignant melanoma?
In white skin people-increases since 1975
In other skinned people-pretty stable and very low
higher incidence in UK in south coast-high sun exposure
What does basal cell carcinoma look like?
Glistens, pinky/greyish/reddish with dilated small vessels-can see
What does malignant melaboma look like?
Dark, uneven borders, lumpy, new
What form of UV exist and why is it an issue?
UVC is blocked by atmospthere
UVB more importan wavelength in skin carcinogenesis
UVA-100 more abundant on earth-also contributes
UVB-causes cross linking of C and T bases with same or each other
normally repaured with excision repair
If damage happens in DNA repair gens-can cause evn more damage
What is xeroderma pigmentosum?
No DNA repair mechanism-genetic mutation
very early and agressive skin cancer (before even 5)
only treatment is complete sun protection
What 3 types of mutation cause skin cancer?
Mutation that stimulate cell prolferation
Mutation that alter response to growth stimuli/repression
Mutations that affect apoptosis
Describe what are the 3 fates of cell after being sun damaged?
Either repair
Either damage too serious-apoptose
Or if mutation in repair DNA-can become cancerous
Whta is the relation between sun, immunology and cancer?
Sun depletes langerhans cells in the epidermis-cause immunosupression-> cancer can rise easier, and less cells are cleared
also used for therapy-like psoriasis-supress resposne but can increase skin cancer incidence
What are the 6 skin types accodring to fitzpatrick phototypes
1-always burns, never tan 2-usually, sometimes 3-sometimes-usually tans IV-never burns-always tans V-Moderate constititive tan VI-marked constitutive tan (african)
1-2 highest chances of damage
What is melanin
Produce by melanocytes and causes skincolor
skin color is dependent on amount baseline made, NOT number of cells
melanocytes site on basal membrane of epidermis
melanin produced from tyrosin via series of enzymes
after UV, melanocytes are stimulated-melanin produced more-taken up by keratinocytes-melanin placed around nucleus giving it UV protection
ratio usually 1:6 (melano:keratino)
2 types of melanin-eumelanin and phaemelanin
eu-brown
phaeo-yellowish/reddish (what red hairs produce most of)
variation of ratio of each produces causes variation of skin color/eye/hair
What is a malignant melanoma? What types are there
Malignant tumour of melanocytes
atrypical cells and architecture
causes by UV and genetic factors
risk of metastases
nodular – melanocytes tend to spread upwards-hallmark of melanoma -risk of metastasis (high risk)
lentigo melanoma Before breach epidermis-in situ–quite common in elderly patient-flat dark patches-excise + skin graft
often irregular edges
lateral spreading malignant melanoma-invasive (less than upward)
Acral lentiginous-on wird places
Amelanomic melanoma-no pigment but is melanoma
What the ABCD(E) rule of malignant melanoma?
asymterym border irregulaty
color varyation, diamter (growing/7mm
Erythrema
ABCDE
can lose/not be pigmented-amleranomic
on feet-always flat plques-acral lentiginous
