Skin cancer – Malignant melanoma
Malignant melanoma is a malignant tumour of melanocytes, usually arising in the epidermis. It is the most lethal of the main skin tumours and has increased in incidence over the last three decades. The important pathogenic role of excessive ultraviolet (UV) radiation exposure has been the subject of public education campaigns. Genetics may be important, and up to 5% of patients have a family history of malignant melanoma.
Clinical presentation
Four main clinicopathological variants are recognized. These are described below.
Superficial spreading malignant melanoma
This type accounts for 50% of all British cases, shows a female preponderance and is commonest on the lower leg. The tumour is macular and shows variable pigmentation, often with regression (Fig. 1).
Lentigo malignant melanoma
Malignant melanoma developing in a longstanding lentigo maligna (Fig. 2) constitutes 15% of UK cases. A lentigo maligna arises in sun-damaged skin, often on the face of an elderly person who has spent many years in an outdoor occupation.
Acral lentiginous malignant melanoma
The acral lentiginous type makes up 1 in 10 of British cases, but is the commonest form in dark-skinned races. The tumour affects the palms, soles (Fig. 3) and nail beds, is often diagnosed late and has poor survival figures.
