Malignant Melanoma Flashcards
What is the role of melanocytes?
Produce melanin - a protein that helps protect against harmful UV exposure.
Number of melanocytes in darker vs white skin?
Melanocytes are found in equal numbers in different skin tones. However, darker skin produces more melanin.
Therefore, damage caused by UV exposure is more likely in white skin compared to dark-brown or black skin.
Where is melanoma in situ confined to?
Epidermis
When melanocytes grow in a non-cancerous way, what do they result in?
- Moles (benign melanocytic naevi)
- Freckles (lentigines and phelides)
What are the 4 common subtypes of melanoma?
1) Superficial spreading melanoma
2) Nodular melanoma
3) Lentigo maligna melanoma
4) Acral lentiginous melanoma
What is the most common type of melanoma?
Superficial spreading melanoma (70% of cases)
Where does superficial spreading melanoma typically affect?
- arms
- legs
- back
- chest
Describe growth of superficial spreading melanoma
1) Malignant melanoma cells have a longer ‘in situ’ phase (months to years).
2) Initially grows horizontally (radial growth phase), presenting as a flat, irregularly pigmented lesion that slowly enlarges.
3) As invasion continues, the growth may become vertical.
What is the most aggressive type of melanoma?
Nodular
Growth of nodular melanoma?
Malignant melanoma cells invade vertically, presenting as a nodule that grows rapidly (weeks to months).
What type of melanoma often bleeds or ulcerates?
Nodular
What is the precursor lesion to lentigo maligna melanoma?
Lentigo maligna
What is lentigo maligna directly related to?
Sun exposure
Typical age that superficial spreading vs lentigo maligna affects?
Superficial spreading - younger people
Lentigo maligna - older people
Where does acral lentiginous melanoma typically appear?
Palms, soles or under the nails.
Often diagnosed at a late stage due to their location.
What are some risk factors for melanoma?
- History of skin cancer, melanoma, or atypical naevi
- FH of melanoma
- Pale skin (Fitzpatrick skin type I and II)
- Red or light-coloured hair
- High freckle density
- Light coloured eyes
- History of sunburn
- Sun exposure or tanning bed exposure
- Large amounts of moles
- Increasing age
- Immunosuppression
What genetic condition has a skin cancer predisposition?
xeroderma pigmentosum
What is amelanotic melanoma?
Melanoma with no pigment, appears as pink or red lesion.
The ABCDE criteria are used to describe features that most melanomas have.
What is this?
A - asymmetrical shape
B - border irregularity, including poorly defined margins
C - colour change and variation
D - diameter of the mole (most melanomas are >6mm)
E - evolving (such as changing in size, shape or colour)
What diameter are most melanomas?
> 6mm
Seborrhoeic keratoses is a differential for melanoma.
What is this?
A common and benign class of lesion that can score highly on the ABCDE criteria are seborrhoeic keratoses (also called seborrhoeic warts).
Lesions suspicious for melanoma are excised for histology.
What are the lateral margins?
2-3mm
How is a diagnosis of melanoma confirmed?
full-thickness excisional skin biopsy
What are the main diagnostic features for melanoma (major criteria)?
1) Change in size
2) Change in shape
3) Change in colour
What are the 2ary features of melanoma (minor criteria)?
1) Diameter >= 7mm
2) Inflammation
3) Oozing or bleeding
4) Altered sensation
What is Breslow thickness?
Measures the thickness of invasive melanoma in mm from the GRANULAR cell layer to the DEEPEST tumour cell.
What are the different stages of melanoma?
Stage 0 - ‘in situ’
Stage 1 - <2mm in thickness
Stage 2 - >2mm in thickness, or >1mm in thickness w/ ulceration
Stage 3 - spread to involve local lymph nodes
Stage 4 - mets to distant sites
What is the main mx of melanoma?
Wide local excision
What are the recommended excision margins of tissue around the melanoma for:
1) Stage 0
2) Stage 1
3) Stage 2
1) 0.5cm
2) 1cm
3) 2cm
When is a sentinel lymph node biopsy indicated in melanoma?
Breslow thickness >0.8mm
When is a sentinel lymph node biopsy normally completed?
Same time as surgical excision
What is the single most important factor in determining prognosis of patients with malignant melanoma?
Breslow depth
Approx 5 year survival of Breslow depth >4mm?
50%
Approx 5 year survival of Breslow depth <0.75mm?
95-100%
