Pictorial case study - Concern about changes to a mole

With a family history of malignant melanoma, this patient was worried when he noticed changes in his skin, explains Dr Jean Watkins.


This 71-year-old man had numerous moles. His mother and brother had developed malignant melanoma (MM) and following their advice, he kept watch on his moles in case any appeared to change.

He was concerned that in the past few weeks, a mole on his chest had become darker, increased in size and bled at times.

With this history and findings on examination, the GP found a lesion that had become raised, irregular and asymmetrical in outline, and measured 1.5cm across. This led to an urgent referral, because it was assumed this was MM. There were no enlarged regional lymph nodes.


MM may occur at any age, but is the most common cancer in patients aged 15-34. Warning signs are a new or changing lesion becoming larger than 6mm in diameter, an irregular and asymmetrical outline, and variable or changing colour (black, brown or blue). All suspected cases should be referred urgently to a specialist unit.

The dermatologist agreed with the diagnosis, which was further established with the aid of a dermatoscope. An atypical pigment network and vascular pattern, and a bluish white veil, are all suggestive. The lesion was excised, allowing a wide margin, and examined histologically. The diagnosis was confirmed and its depth found to be 2mm; further surgery was required to achieve a more adequate margin. The depth of an MM is an indicator to the prognosis, with a 95-100% five-year survival if it is 1mm, 80-96% if it is 1-2mm, 60-75% if it is 1-4mm and 50% if it is >4mm deep.

All patients require follow-up in a specialist unit and should be advised to make regular checks for further suspicious lesions, as should those who might be particularly likely to develop one - for example, those with fair hair, blue eyes and skin that burns easily in the sun, multiple moles or a large hairy mole. Those with a personal or a family history of MM are at greater risk.

The most vulnerable should avoid overexposure to the sun or sunbeds, cover up with a hat and appropriate clothes and use SPF 30 sunscreen. Some may also need to take vitamin D supplements.

Differential diagnosis
  • Benign melanocytic naevus
  • Squamous cell carcinoma
  • Basal cell carcinoma - especially if pigmented
  • Actinic keratosis (pigmented)
  • Blue naevus
  • Halo naevus
  • Haemangioma
  • Metastatic skin tumours

  • Dr Watkins is a retired GP in Hampshire.

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