Melanocytic Naevi & Malignant Melanoma Flashcards
What are melanocytic naevi?
Benign proliferation of melanocytes ( a mole)
can be congenital but most are acquired, most commonly during childhood
What is involved in the aetiology of melanocytic naevi?
aetiology is unclear but factors include:
- genetics
- sun exposure
- immune status
more naevi tend to develop in people who are immunosuppressed or exposed to more sun
What are the clinical features of melanocytic naevi?
- can occur anywhere on the body
- more common in fair skinned people
- usually asymptomatic
- flat or raised
- vary in colour, size and shape
What are the 3 ways in which benign naevi can be classified?
- junctional naevus
- compound naevus
- intradermal naevus
What are the characteristics of a junctional naevus?
- melanocytes sit between the epidermis and the dermis (at the junction between the layers)
- flat
- usually mid to dark brown
What are the features of a compound naevus?
- melanocytes sit within the dermis and at the epidermal-dermal junction
- raised centre with a flat surrounding area
- often hairy
- often lighter in colour than a junctional naevus
What are the features of an intradermal naevus?
- melanocytes found within the dermis
- raised
- often hairy
- much paler in colour than other 2 types
- can progress over time from intradermal to compound and then junctional
Outside of the 3 main classifications of naevi, what are 2 common presentations which may be seen?
Blue naevus:
- sits very deep in the dermis giving a dark blue colour
Spitz naevus:
- has a star like pattern with projections around the periphery
What is a potential complication for someone who has many moles?
Someone with >100 moles is at an increased risk of melanoma
this is often familial
What is the treatment for melanocytic naevi?
Usually there is no treatment but patients are asked to monitor their moles and look for any changes
In some situations they may be surgically removed
For what reasons may a mole be surgically removed?
- if there is uncertainty to whether it is benign or malignant (often if a mole changes or a new one develops)
- if the mole causes problems (e.g. intradermal moles often catch on clothing and bleed)
- for cosmetic reasons (done privately)
What is melanoma and why does it occur?
Skin cancer of the melanocytes that occurs due to uncontrolled melanocyte proliferation
What are the 3 stages of melanoma?
Melanocytes usually sit along the basement membrane of the epidermis
- In-situ melanoma involves the epidermis only
- Invasive melanoma occurs when melanocytes spread to the dermis
- Metastatic melanoma occurs when it spreads elsewhere away from the skin
What is the epidemiology of melanoma like worldwide?
- around 3% of skin cancers
- rare in children
- highest worldwide incidence rate in australia
What are the statistics like for melanoma in the UK?
- 5th most common cancer
- accounts for 4% of cancer cases
- incidence is increasing
What are the risk factors for melanoma?
- High UV exposure (short duration intense UV exposure, especially during childhood)
- Skin type I (always burns, never tans, usually red hair)
- increasing age
- history of skin cancer (incl prev melanoma)
- large numbers of melanocytic naevi (>100 significantly increases risk)
- having >5 atypical naevi
- strong family history of melanoma (more than 3 members having it)
- genetics - BRAF mutation
What are the clinical features of melanoma?
it can occur anywhere on the body (including mucosal sites) but is most common on the back (for men) and the legs (for women)
can be completely asymptomatic
may be itchy, painful, bleed or have an overlying crust
What is an amelanotic melanoma?
a melanoma containing no pigment
this can be difficult to diagnose as it appears as a bland-looking pink plaque
What is the ABCDE approach used when considering whether a mole could be melanoma?
A - Asymmetry
B - Borders:
- are they irregular?
C - Colour:
- is it irregular or is there variation?
- more than 2 colours is a concerning feature
D - Diameter:
- is it >6mm?
E - Evolving:
- is it changing in size/shape/colour?
also note any symptoms such as bleeding, itching or pain
What is the 7 point checklist used in the diagnosis of melanoma?
Major signs:
- change in colour
- change in shape
- change in size
Minor signs:
- diameter >7mm
- inflammation
- altered sensation
- crusting / bleeding / oozing
Should be concerned of melanoma if there is 1 major sign or 2 minor signs
What are the differential diagnoses to consider in melanoma?
- Dysplastic melanocytic naevus (some abnormal changes in the cells but insufficient to be melanoma)
- Squamous cell or basal cell carcinoma (sometimes melanomas can look strange if there is inflammation or no pigment)
What are the characteristics of a superficial spreading melanoma?
- most common type
- grows horizontally within the epidermis (doesn’t tend to be growing as aggressive deeply)
- associated with intermittent high intesity UV exposure
- often on the legs
What are the characteristics of Lentigo Maligna melanoma?
- it grows horizontally
- common in the elderly
- associated with long term UV exposure
- found in areas of high sun exposure such as the face
What are the characteristics of acral lentiginous melanoma / subungual melanoma?
- grows horizontally
- common in the elderly
- found on the palms, soles and nails
What are the characterisitics of nodular melanoma?
- grows vertically
- deeper in the skin
- associated with intermittent high intensity UV exposure
- often on the trunk
What are the treatment options for melanoma?
- surgical excision
- sentinel node biopsy +/- clearance
- radiotherapy (in some cases)
usually excision of 2mm margin then WLE depending on tumour depth (Breslow thickness)
What immunotherapy options are there for refractory widespread melanomas?
- ipilimumab
- nivolumab
- pembrolizumab
What are examples of targeted treatments for refractory widespread melanomas?
- vemurafenib
- dabrafenib
- trametinib
What is the prognosis of melanoma like?
- In situ melanomas are cured with excision
- Invasive melanomas may metastasie or recur
What is the risk of recurrence and/or metastasis of melanoma based on?
Breslow thickness
- <1mm thick - low risk
- 1-4mm thick - intermediate risk
- >4mm thick - high risk
