3: Pathology of pigmented lesions Flashcards
Which aspects of the skin can tumours arise from?
Epidermis
Melanocytes
Dermis
Appendages
Lymphoid elements
What does in-situ mean in relation to invasive?
Limited to epidermis only
From which embryological structure do melanocytes come from?
Neural crest
What are precursor melanocytes called?
Melanoblasts
In which epidermal layer are melanocytes found?
Basal layer
What is the ratio of melanocytes : basal keratinocytes?
1 : 10
____ transfer melanin to ___ through their ___ processes.
Melanocytes , keratinocytes , dendritic
What does melanin protect keratinocytes from?
UV radiation
What is the technical names for freckles?
Ephilides
What are freckles?
Patchy increases in melanin production
When do freckles appear?
After UV exposure
What are actinic lentigines (sing. lentigo)?
“Liver spots”
What is the technical name for a birthmark?
Melanocytic naevi
If a melanocytic naevi is big, what is at risk of turning into?
Melanoma
What are the two main types of naevi?
Congenital and acquired
What term, describing benign abnormal growth, can be used instead of naevi?
Hamartoma
What are the three terms used to describe acquired melanocytic naevi as they sink into the dermis over time?
What does each stage look like?
Junctional - flat and circular
Compound - raised
Intradermal - raised and hairy
What can dysplastic naevi turn into?
Melanoma
The two atypical naevi - ___ naevi and ___ naevi - are totally (benign / malignant).
halo , blue
benign
Which kind of rare naevi occur in children and resemble melanoma, but are actually benign?
Spitz naevi
If you are unsure whether or not a lesion is a benign naevus or a malignant melanoma, refer to?
Dermatology
What can arise from dysplastic naevi?
Malignant melanoma
Malignant melanoma is more common in (men / women),
women
What is the biggest risk factor for developing malignant melanoma?
UV exposure - sun, sunbeds
Malignant melanoma risk is also tied to a person’s ____.
genetics
Where can malignant melanomas arise?
Literally anywhere
What are some signs which should make you suspect malignant melanoma in a skin lesion?
ABCDE
E being changes in shape, size, bleeding, ulceration, new nodules…
What are the four types of melanoma?
Superficial spreading
Acral / mucosal
Lentigo maligna
Nodular
Where do superficial spreading melanomas appear?
Trunk and limbs
Where do acral melanomas appear?
Fingers / toes + nails
What is acral melanoma often mistaken for?
Nail trauma
Where does lentigo maligna melanoma appear?
Why?
Face / neck / scalp
Sun damage
What is lentigo maligna a complicated name for?
Melanoma arising for actinic/solar lentigo - macules of pigment and melanocytes caused by UV damage
What is the difference between lentigo maligna and lentigo maligna melanoma?
Lentigo maligna is confined to the epidermis and hasn’t started to invade yet
Lentigo maligna melanoma is invading
What are the two phases of malignant melanoma growth?
Radial / Horizontal growth phase - tumour is in-situ
Vertical growth phase - tumour is invading dermis
Only melanomas in the (horizontal / vertical) growth phase can metastasise.
vertical
What type of melanoma is considered more aggresive because it goes straight into the vertical growth phase?
Nodular melanoma
What does the Breslow thickness measure?
Distance from deepest part of tumour to the granular layer
Apart from a high Breslow thickness, what are two another indicator of poor melanoma prognosis?
Bleeding
Ulceration
By which means can melanoma spread around the body?
Lymph nodes > Lymphatics
Blood vessels
Where can metastatic melanoma end up?
Heart
Lungs
Liver
GI tract
Brain
Skin
If a melanoma is less than 1mm thick, what margin of skin is excised around it?
> 1mm?
1cm
2cm
What else can be removed along with the malignant melanoma itself?
Lymph nodes
How is advanced malignant melanoma treated?
Chemotherapy
Immunotherapy
Mutations of which gene are responsible for malignant melanoma on sun-exposed skin?
B-RAF
Which type of gene is B-RAF?
Oncogene
The proto-oncogene for B-RAF is very (strong / weak).
weak
Which pathway is involved in malignant melanoma on sun-exposed skin?
RAS / RAF / MAPK pathway
Which drug can be used to block the RAS / RAF / MAPK pathway to treat malignant melanoma?
Imatinib
