Definition

A melanoma of the skin is a malignant tumour arising from melanocytes in the skin.

Subtypes

Other types of pigmented lesions include:

Moles (naevi) — including blue naevi, halo naevi, and Meyerson's naevi.
Seborrhoeic keratoses.
Dermatofibromas.
Freckles.
Lentigines.
Pigmented basal cell carcinomas.

Malignant Melanoma

Superficial spreading melanoma
Nodular melanoma
Lentigo maligna melanoma
Acral lentiginous melanoma (soles of feet, palms of hands, nail bed).

Prevalence

• There are 8100 new cases of malignant melanoma in the UK each year

• The age-adjusted incidence is 17 per 100,000 in the UK

• Melanoma is the second most common cancer in adults aged between 25 and 49

• The incidence of melanoma in England is increasing faster in males than in females

Risk factors

• A personal history of skin cancer.

• A family history of skin cancer.

• Pale skin (type I and II) that does not tan easily and burns; light-coloured eyes.

• Red, blond or light-coloured hair.

• Blue or green eyes.

• History of sunburn, particularly blistering sunburn in childhood.

• A history of indoor tanning.

• A large number of moles.

• Increasing age.

• Organ transplant recipients.

Diagnosis

Pigmented lesions which 'stand out from the crowd' because they are different (the 'Ugly Duckling sign') are a cause for concern, especially if they are changing.

The Weighted 7-point checklist may be used to assess pigmented skin lesions, and determine referral:

Suspicion is greater for lesions scoring 3 points or more.
However, if there are strong concerns about cancer, any one feature is adequate to prompt urgent referral under the 2-week rule.

Ideally review the lesion under a Dermatoscope. 

Minor features of the lesion (1 point each):
largest diameter 7 mm or more
inflammation
oozing or crusting of the lesion
change in sensation (including itch)

Major features of the lesion (2 points each):
change in size
irregular shape or border
irregular colour

Examine other areas

• Inspect the rest of the skin for suspicious pigmented lesions or dysplastic naevi.

• Palpate major lymph nodes in the regional drainage area if the lesion is suspicious of melanoma.

Do not biopsy in primary care if melanoma is suspected or the diagnosis is uncertain

Images (Courtesy of Wikimedia Commons and NCI Visuals Online National Cancer Institute)

Urgent referral (within 2 weeks) to Dermatology

1. Lesions suggestive of malignant melanoma (including nodular and amelanotic melanoma).

2. Lesions which score 3 points or more on the 7-point checklist.
   However, any one feature can be adequate to prompt urgent referral.

3. New nodules, which are pigmented, or vascular in appearance.

4. Nail changes, such as a new pigmented line in the nail or something growing under the nail.

5. Any doubt about the diagnosis of the lesion.

6. Skin conditions which are persistent or slowly evolving and unresponsive to treatment, with an uncertain diagnosis and melanoma is a possibility.

7. Biopsy confirmed diagnosis of malignant melanoma. Excision of suspected melanoma in primary care should be avoided.

Prognosis

Prognosis is dependent on the stage of the melanoma, which depends on the thickness, level of ulceration and spread to local lymph nodes.

Survival rates relate to the stage of the melanoma, with a 5-year survival of around 95% for people with stage 1A melanoma (less than 1 mm thickness; no ulceration; mitoses less than 1 mm-2), compared with 7–19% of people with stage 4 melanoma (spread to distant lymph nodes or other parts of the body)