Moles

Moles do confer a malignant potential, although this risk is low. Malignant melanoma (MM) arises de-novo in 70% of cases. Any changing mole should be assessed with the following risk factors in mind.

Risk factors for MM:

1. Over 100 moles or >50 moles on the trunk.

2. Fair skin, blue eyes and freckles.

3. Atypical moles (large irregular moles).

4. Large permanent lentigines on shoulders (giant freckles) indicative of solar damage.

5. Moles on the buttocks, palms and soles.

6. >40 years old.

7. Family history of atypical mole syndrome or MM.

8. Large (>5 cm diameter) congenital moles.

What Matters Most in Pigmented Lesions?

1. Changing Mole:

Change in shape

Change in colour

Change in size

2. Does it have a ragged outline? Ordinary moles are smooth and regular.

3. Does it have a variable pigmentation within it? Shades of brown and black. Ordinary moles may be brown or black but usually are of one shade. Moles surrounded by an area of depigmentation are called halo naevi and are benign. A new halo naevus occurring on an adult is rarely a sign of a immunological response to a MM and should prompt a search of other skin sites.

Many patients are referred with typical seborrhoeic keratoses. These are raised lesions with a warty pigmented surface and a “stuck on” greasy appearance. Please identify these and treat if required with cryotherapy or curette and cautery in general practice.

Dermatofibromata are firm nodules in the dermis and are lightly pigmented and feel like a button in the skin when squeezed. They occur especially on the legs and are a benign reaction probably to an insect bite.

If you suspect melanoma, please refer on the 2 week rule proforma. If you have a patient with a pigmented lesion that you are concerned about but are not sure whether it is a melanoma we would see these patients outside of the two week rule but urgently. If in doubt, an excision biopsy is perfectly acceptable.