ABSTRACT
Moles and Melanomas A melanoma is a malignant tumour of melanocytes. The majority of melanomas originate in the skin but a few can arise from benign naevi. They are caused by excessive ultraviolet exposure and it is widely believed that extreme sun exposure, resulting in sunburn, is linked to the development of melanomas. Melanomas are commonly found on the backs of men and on the legs of women, in particular areas that may be exposed to the open sun. Other causes of melanomas include the use of sunbeds (UVA rays) as well as mutations of the BRAF gene. Melanomas represent the most lethal form of skin cancer and consequently earlier detection gives patients a better chance of survival. [Mnemonic: ABCDE] If a mole has Asymmetry, Border irregularity, Colour irregularity (multiple colours), Diameter enlarging (or greater than 5mm) or Evolving (changing in shape, size, colour, itching or bleeding) it should be examined to determine if it is a malignant melanoma. An excisional biopsy should be performed to determine histologically if malignancy is present as well as tumour thickness (‘Breslow’s thickness’) before surgically removing it. Breslow’s thickness is an important prognostic factor in melanomas. Generally melanomas less than 1mm thick have a 90% 5-year survival rate while those greater than 4mm thick have only a 50% 5-year survival rate. When performing a wide local excision (WLE) of the melanoma a 1cm margin of normal skin around the melanoma is removed for every millimetre of thickness up to a maximum radius of 3cm, after which no extra benefi t is achieved. Preventative measures include taking sun protection measures such as avoiding excessive sun exposure (between 11 am and 3 pm), wearing protective clothing such as long-sleeved shirts, long trousers and hats. The use of sunscreens with an SPF rating of 30 or better on exposed areas can also minimise the risk of burning.
