Alternative names: Melanoma, skin cancer, cancerous mole
Malignant Melanoma is a skin cancer accounting for around 3% of skin cancer in the UK. It is a malignant tumour arising from the melanocytes – the cells that produce brown pigment and moles. When melanocytes become malignant they form melanoma, but a pre-cancerous variant called lentigo maligna exists. In the early stages, melanoma can be slow-growing, in later stages it has the potential to spread (or metastasise) to other areas of the body.
Melanomas tend to resemble a mole that is undergoing changes in size, shape or colour. They may become lumpy or ‘nodular’ and even ulcerate with bleeding. Sometimes they occur in a pre-existing mole, but around half the time they arise in an area or normal skin.
A: Asymmetry – the mole looks unusual, asymmetrical or irregular
B: Border – the border becomes blurred, ill-defined or irregular
C: Colour – more than 2 colours appear in the mole including brown, black or light areas giving a mottled appearance. A very dark or black appearance can occur
D: Diameter – if a mole is enlarging it should be reviewed.
Pre-melanoma (lentigo maligna) and the earliest phase of melanoma (in-situ melanoma) are almost always cured with surgery. For melanoma beyond these early stages, it is the depth into the skin that the melanoma reaches that tells us how the disease might behave. This depth is termed the ’Breslow thickness’. The Breslow thickness will determine whether you require a simple excision or further more complex surgery including lymph gland biopsy.
The degree of spread a melanoma has undergone will be classified by stages:
Stage I: Localised to the original site only
Stage II: Localised to the skin only – the original site plus local skin spread
Stage III: Spread to the nearby lymph glands
Stage IV: Spread to the internal organs of the body
All melanomas are treated by excision. The tumour is then assessed under the microscope and the next step will depend on the Breslow thickness. With the diagnosis confirmed, a further operation will be required to excise the scar (wide local excision). This extent of this wide local will depend on the Breslow thickness (as does the likelihood of spread or recurrence). If this is greater than 1 mm, a biopsy of the lymph glands will also be required. Should there be melanoma present in the lymph glands, further surgery will be required.