Melanoma or benign mole?
One in 200 pigmented lesions will be a melanoma presented by patients Dr Stephen Hayes advises on making a confident diagnosis
Dr Stephen Hayes advises on making a confident diagnosis
If melanoma were an animal it would be a black mamba: if bitten you have a few hours to get antivenin or die. Similarly, with melanoma there is a window of opportunity between initial visible change and metastasis when correct action is lifesaving. Dermatology departments will therefore see suspicious lesions within two weeks of a proper referral.
The image of melanoma as a nodular, ulcerated, bleeding lesion should be banished from our minds: these late tumours will probably have already spread. We must look for early, thin melanomas, which are usually curable.
The incidence of malignant melanoma increased by 64 per cent during the decade of the 1990s, continuing the steep upward trend since the 1950s. In 1999 there were 8,000 new cases and 1,650 deaths. Because of past UV exposure, and given a timelag of at least 15 years from exposure to melanoma, these figures will continue rising.
Triage in primary care
Around one in 200 lesions presented by anxious patients will be a melanoma most of the rest will be harmless. They can't all be referred or clinics would be overwhelmed. We must therefore optimise our diagnostic skills and triage efficiently.
Lesions can be triaged into the following groups:
· Obviously benign
· Obviously malignant
Obviously malignant and doubtful should be referred. What is obvious to one doctor, however, is doubtful to another, depending on their experience and training, which are uneven due to an educational deficit in GP dermatology. Attendance at teaching clinics is ideal if possible, but books and internet learning resources can help (see information box).
Local dermatologists can be asked to teach, perhaps on protected learning half-days. Nurses and other clinical staff may be the first to see a suspicious lesion so they should be trained too. I recently saw a patient whose melanoma on the back was spotted by a mammographer.
Seborrhoeic keratoses, otherwise known as seborrhoeic warts or basal cell papillomas (BCPs), are common in the over-70s. They are slow-growing, mainly occur on the trunk and head, and range in colour from pale yellow to jet-black through all shades of brown in between. Colour is usually even.
They have a 'stuck on' appearance and usually a regular oval or round border. Larger lesions will have fissures, crypts and keratin cysts, which look like comedones. These signs are easier to see with a lens and a good light, better still with a dermatoscope.
If a positive diagnosis of seborrhoeic keratoses is made the patient should be reassured and if required treated with cryotherapy or curettage and cautery in primary care.
Dermatofibromas occur most often on the limbs and shoulders. There may be a history of insect bite. When pigmented or with a dark perimeter they may cause concern, especially on the leg of a sunburned woman.
Positive features include the round, even nature of the lesion and its texture. No other skin lesion is so hard when palpated between finger and thumb it feels like a dried pea and the skin puckers around it as it is squeezed.
I avoid excising these because the scar is often worse than the lesion, especially on shoulders or calf.
Benign mole or melanoma?
Moles (melanocytic naevi) vary considerably in appearance. The diagnostic process starts with the history (see box below). Changes of significance are changes in size, colour, shape and sensation. The story may be vague, especially when the lesion is on the back. Spouses may be lifesaving.
Children It is normal for moles to appear and change gradually over time in children. Melanoma under the age of 15 is practically unheard of except in the rare syndrome xeroderma pigmentosum and congenital giant naevi. Reassurance is the order of the day in most children when parents are worried about a new or changing mole.
Examination Good light and a magnifying glass are essential. I use a four-inch glass lens that I got from a discount store for £1.50. Ideally, the whole skin should be examined I have found cancers on the back of a patient who presented about something on the face.
Background Sun-damaged skin, multiple freckles, or the presence of more than 30 moles, including irregular ones, increase the risk. Also the back (especially in men) and the lower leg (especially in women) are worrying sites for a new mole melanomas often occur at these sunburn-exposed sites.
Specific features I use the ABCDEF guide, which is as follows:
· A for asymmetry symmetry is reassuring
· B for border, which should be regular without indentations or projections
· C for colour, which should be even, the paler the better three colours is worrying, although two colours can be accepted if symmetrical and no other suspicious features
· D for diameter moles larger than 6mm are of concern
· E for erythema (or elevation)
· F for funny-looking moles.
No single feature is diagnostic, they should be taken together and a judgment made. Fundamentally, you are looking for irregularity and change. If in doubt, refer. Hospitals are obliged to see all suspected melanoma patients (not BCCs these can wait) within two weeks. Delays may occur if the referral is not made correctly and faxed. Check your local guidelines and use them.
This is an illuminated x10 lens that uses oil to break down refraction and see further into the skin, revealing features not visible to the naked eye. In trained hands it can improve the diagnosis of uncertain lesions. A basic but satisfactory model sells for around £150. Do not consider using a dermatoscope to distinguish between harmless and deadly moles without training at least get the book by Menzies (see information box).
In summary, GPs and other members of the clinical team must learn to:
· Recognise benign lesions confidently
· Refer suspicious lesions promptly and correctly
· Use the consultation for opportunistic education.
Melanoma is a killer that offers no second chances. Please read the obituary of Kathryn Rhian James of April 1997 on bmj.com to see what happened to a fine young doctor with a mole on her leg that wasn't treated in time.
Melanoma should be treated in hospital, but education, initial triage, early diagnosis and appropriate referral are the keys to reducing mortality. That's our job in primary care, and if we don't have the resources, we must argue for them on the grounds that melanoma now kills many more patients than cervical cancer, for which we screen.
Stephen Hayes is a hospital practitioner in dermatology and a GP tutor in Hampshire
·www.dermis.net is a free site with over 7,000 dermatology images, including more than 100 pictures of melanoma. A useful exercise is to scroll through these and use the ABCDEF sieve to say why each is a melanoma.
·An Atlas of Surface Microscopy of Pigmented Skin Lesions: Dermoscopy (McGraw Hill, 2003), by Scott Menzies et al, is an essential guide to the use of the dermatoscope in the differential diagnosis of pigmented lesions. The new edition has a CD-ROM with many images of pigmented lesions and interactive
self-assessment quiz mode. A must for anyone who wishes to use the dermatoscope to improve diagnosis of pigmented lesions.
·The Primary Care Dermatology Society promotes GP dermatology and arranges educational conferences around the country. Details on the new website at www.pcds.org.uk
·The PCDS is affiliated to the British Association of Dermatologists, whose website www.bad.org.uk has a wealth of dermatology guidelines and links.
Has the patient:
· Lived in sunny countries (especially before age 15)?
· A positive family history of melanoma?
· Red/blonde hair?
· A history of sunburn?
· Duration of mole
· Change in colour
· Change in shape
Melanoma: five-year survival rates
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Distant spread close to zero
NB: Survival rates are related to tumour depth at excision. Radiotherapy and chemotherapy are of little or no benefit in metastatic disease.