Melanoma Flashcards
where do melanomas arise from
melanocytes
where are melanocytes found in the skin
scattered along the basal layer of the epidermis
why is melanoma the most serious form of skin cancer
- metastasis can occur early - number of deaths even in young people
risk factors
- Pale skin
- Previous invasive melanoma or melanoma in situ
- Increasing age
- Previous BCC or SCC
- Multiple melanocytic naevi
- Sun sensitivity
- Immunosuppression
- Atypical mole syndrome
- Lentigo maligna
outline the 3 phases of melanoma growth
- in situ - tumour is confined to the epidermis
- invasive - tumour has spread to the dermis
- they may now spread via lymphatics or blood stream
- metastatic - has spread to other tissues
how may tumours spread in situ
may spread out within the epidermis - the horizontal growth phase
what does melanoma survival depend on
Breslow depth - the deepest tumour from the granular layer in mm
Breslow depth prognostic values
- pTis-melanoma is in-situ-100% survival
- pT1-tumour < 1mm-90% survival (still in epidermis?)
- pT2-tumour is 1-2mm-80% survival
- pT3-tumour is 2-4mm-55% survival
- pT4-tumour > 4mm thick-20% survival
what sign is used to identify melanomas
ugly duckling sign
ABCDE rules
Asymmetry, Border, Colour, Diameter (>6mm), Evolution.
why are nodular melanomas so bad
they have a vertical growth phase
how does melanoma appearance change in horizontal and vertical growth phase
Melanoma is normally flat during the horizontal growth phase and becomes thickened and raised during the vertical phase
which types of melanoma are associated with horizontal and vertical growth phases
- Horizontal growth phase: SSM, lentigo maligna melanoma and acrallentignous melanoma.*
- Vertical growth phase: nodular, spitzoid, mucosal*
what is the most common type of horizontal melanoma
superficial spreading melanoma
presentation of SSM
- slowly enlarging flat area of discoloured skin
- irregular shape
outline the course of SSM
- malignant cells remain in situ for a longer period of time - months to decades
- have a primary horizontal (radial) growth phase
- some can become invasive, a nodular melanoma can arise within one
how may deep and invasive SSM present
they may itch , sting or blled
Acral/Mucosal Lentiginous Melanoma
- characterised by their site of origin: palms of hands, soles of feet or subungually
- relatively rare in comparison to other types
who are Acral/Mucosal Lentiginous Melanoma more common in
people with darker skins
are Acral/Mucosal Lentiginous Melanoma related to sun exposure
they may not be
course of Acral/Mucosal Lentiginous Melanoma
- remain in situ for years, non invasive
- nodular melanoma can arise within them
appearance of Acral/Mucosal Lentiginous Melanoma
- Start off with a smooth surface, which later may become thicker with an irregular dry/warty surface
- May ulcerate or bleed
what is lentigo maligna melanoma related to, hence who and where is it seen
- sun exposure
- seen on sun damaged face/neck/scalp in older people
- risk relates to sun damage, more common in outdoor workers, solar damage, older people and keratinocyte skin damage (e.g. BCC, SCC)
what is the precursor to lentigo maligna melanoma
- lentigo maligna - Hutchison’s freckle
- this is where a large facial mole undergoes central melanomatous change, the cells are still confined to the epidermis - in situ
how does lentigo maligna present
- slow growing macular area of pigmentation seen in elderly people, commonly on the face
what is the risk of developing invasive malignant melanoma from lentigo maligna
- slightly increase risk, increasing with larger lesions
- but there is a lower risk than there is with other forms of melanoma in situ
when is a lentigo maligna melanoma diagnosed
when the malignant melanoma cells have entered the dermis and deeper layers of skin
presentation of lengtio maligna melanoma
- Large size (>6mm), irregular, variable pigmentation and smooth surface
nodular malignant melanoma
- Most aggressive type, grows rapidly from the start. Presents as rapidly growing pigmented nodule which bleeds or ulcerates.
- Has a vertical growth phase, which is more dangerous than the horizontal growth phase
what contributes to prognosis, along with Breslow depth
ulceration
what suffix is used in tumour staging to represent ulceration
B
treatment options for melanoma
- primary excision
- advanced disease may require chemo, immunotherapy or genetic therapies
how much around the lesion must be cleared
- If in-situ then clear by circa 5mm
- If invasive but <1mm thick: 1cm clearance
- If invasive and >1mm thick: 2cm clearance
indications for sentinel node biopsy
>1mm thick or thinner with mitoses
mitotic rate
reflects cellular proliferation within the primary tumour, is an important predictor of survival
which mutation is often found in acral melanomas, and which drug targets it
c - kit mutation, imatinib
which mutation is often found in melanomas on intermittently sun exposed skin
BRAF, stimulates MAPK pathway which stimulates cell division
drugs that target BRAF
dabrafenib and vemurafenib
what may improve responses to BRAF inhibitors etc
MEK inhibitor eg Tramatenib
