Melanoma is a potentially deadly skin cancer affecting over 4,000 New Zealanders annually. It can either arise from pigment cells (melanocytes) in normal skin or form existing moles. As with all skin cancers early diagnosis is very important. Many melanomas can be cured when treated early.
At KM Surgical & Dermatology Associates your dermatologist is able to perform a full body skin check and detect lesions suspicious for melanoma or other skin cancers accurately. This may involve use of dermoscopy, a technique that utilises an optical device called a dermatoscope to assess the lesion more precisely. It takes years of training to perform dermoscopy accurately and dermatologists are best trained to do this.
Treatment options include surgical excision with a narrow margin, also known as a diagnostic excision. Once a diagnosis of melanoma is made the specific characteristics of the melanoma determine what the next best course of action is. This may include a wider re-excision of the scar with or without a sentinel node biopsy and/or medical treatment. You may need to be referred to a plastic surgeon or oncologist for additional investigations and/or treatment.
This information is for guidance only and is not a substitute for a medical consultation.
For more information
https://www.dermnetnz.org/
How does melanoma develop?
Most melanomas are caused by burning exposure to sunlight (UV radiation) in individuals with a genetic predisposition. Sun burn in childhood is associated with a high risk of melanoma in later life.
It is important to use a high SPF sunscreen, wear a hat, sunglasses and clothing. Sunbeds provide exposure to UV radiation which is mainly ultraviolet A (UVA) but this is now known to cause melanoma in addition to ageing the skin.
Melanoma develops as a uncontrolled growth of pigment cells (melanocytes). Normal melanocytes are found in the basal layer of the epidermis, which is the lower part of the outer layer of the skin.
Melanocytes produce a protein called melanin, which protects the skin by absorbing radiation.
Melanocytes are found in equal numbers in black and in white skin but melanocytes in black skin produce much more melanin. People with darker skin are very much less likely to be damaged by UV radiation than those with fair skin.
Non-cancerous growth of melanocytes results in moles (properly called benign melanocytic naevi) and freckles (lentigines and ephelides). Cancerous growth of melanocytes results in melanoma.
Can moles turn into a melanoma?
Yes, but a common mole rarely turns into melanoma and melanoma can develop de novo, so taking off moles does not eliminate the risk of developing.
Although common moles are not cancerous, people who have a high mole count have an increased chance of developing melanoma.
It is important that you check your skin regularly and if you notice any of the following changes in a common mole or in a mole like spots you should report to your dermatologist.
- The colour changes
- It gets unevenly smaller or bigger
- It changes in shape, texture, or height
- The skin on the surface becomes dry or scaly
- It becomes hard or feels lumpy
- It starts to itch
- It bleeds or oozes
The A-G of Melamona
- A - Asymmetry
- B - Border irregularity
- C - Colour variation
- D - Diameter over 6 mm
- E - Evolving, Elevated (enlarging, changing)
- F - Firm
- G - Growing
Not all melanomas are dark in colour.
Occasionally an aggressive melanoma will not be darkly coloured. It is important to report any new, different and slowly changing lesion.
Who is at risk of Melanoma?
The main risk factors for developing the most common type of melanoma (superficial spreading melanoma) include:
- Increasing age
- Previous non-malanoma skin cancer
- Previous invasive melanoma or melanoma in situ
- Many melanocytic naevi (moles)
- Atypical naevi (moles) of any sort
- Strong family history of melanoma
- Fair skin that burns easily
Types of Melanoma
Melanomas are described according to their appearance and behaviour. Those that start off as flat patches (i.e. have a horizontal growth phase) include:
- Superficial spreading melanoma
- Lentigo maligna melanoma (sun damaged skin of face, scalp and neck)
- Acral lentiginous melanoma (on soles of feet, palms of hands or under the nails – the subungual melanoma)
These superficial forms of melanoma tend to grow slowly, but at any time, they may begin to thicken up or develop a nodule (i.e. progress to a vertical growth phase).
Melanomas that quickly involve deeper tissues include:
- Nodular melanoma (presenting as a rapidly enlarging lump)
- Mucosal melanoma (arising on lips, eyelids, vulva, penis, anus)
- Neurotropic and desmoplastic melanoma (fibrous tumour with a tendency to grow down nerves)
Combinations may arise for example nodular melanoma arising within a superficial spreading melanoma or desmoplastic melanoma arising within a lentigo maligna.