BENIGN & MALIGNANT MELANOCYTIC LESIONS Flashcards
(31 cards)
what is a congenital naevi + how common are they
lesion present at birth - 1% of newborns
what is an example of highly malignant naevi
giant ‘bathing trunk’ naevi
what is the mongolian blue spot
benign congenital lesion due to melanocytes in dermis common in asian ethnicities
what is an acquired naevi
naevi appearing around adolescence - changes with age
what are the types of acquired naevi and what do they look like
junctional - macular and dark intradermal - raised and skin colour compound - warty halo - naevus with hypopigmented area surrounding it blue - black/blue naevus
what does an asymmetrical naevus look like
asymmetrical
differently pigmented
what are asymmetrical naevi associated with
familial or due to excessive sun exposure in childhood
whats the prevalence of asymmetrical naevi
2-5%
when do asymmetrical naevi have a higher risk of melanoma
> 50 yrs
family history
whats in incidence of malignant melanoma for men and women in the UK
- 8/100,000 for men (0.0078%)
12. 3/100,000 for women (0.0123%)
what are risk factors for melignant melanoma
fair skin
excessive skin exposure in childhood - especially if multiple severe sunburns in childhood
family history
immunosuppresion
multiple atypical moles
>3 blistering sunburns under 20 yrs old
previous PUVA/immunosuppression/dysplastic naevi
large number of atypical/dysplastic naevi/large congenital naevi
whats the most important prognostic factor for malignant melanomas
breslow thickness - histological distance from deepest melanoma cells to stratum granulosa of the epidermis
what are the data ranges for risk for breslow thickness
<0.76mm - low risk
>1.5mm - high risk
apart from breslow thickness what are other poor prognostic factors for malignant melanoma
lesions on head and neck
being male
older age group
ulceration
what are sinister features of a lesion that make you suspicious of malignancy
change in size irregular shape irregular colour greater than 1cm diameter itch bleeding/ulceration
where in the epidermis do melanomas begin
basal cell layer
what is in situ melanoma and what is another name for it
all malignant cells are confined to epidermis - lentigo maligna
what are the subtypes of melanoma and the % they account for
superficial spreading - 70% lentigo maligna melanoma 4-15% acral lentiginous - 5% nodular melanoma - 5% amelanotic - 4% desmoplastic - <4%
what subtype of melanoma is more common in those with darker skin
acral lentiginous
where is superficial spreading malignant melanoma usually found
legs of women, trunks of men
how do superficial spreading malignant melanoma grow
initially horizontally in superficial layer of skin, then after a variable amount of time it will grow vertically
in what population do you usually see lentigo maligna melanomas
elderly patients, they also tend to have features of sun damage
what do lentigo maligna melanomas arise from
long standing lesions from lentigo melanomas
where do acral lentiginous melanomas tend to grow
extremities - palms/soles of feet
