A suspicious history of recent change in a mole on the back
A middle aged male presented with a history of a ‘mole’ on his upper back. He did not know how long it had been there but it had recently begun to itch and scab.
On examination there were a dozen moles on the back, one looked different to all the others, the ‘ugly duckling’ sign. One’s eyes were drawn to it immediately.
The lesion is irregular in outline and colour, dark and very different from the other pigmented lesions. Only one thing to do-dermoscope it!
There are essentially two structure zones here. from 3 to 6 o’clock there is a roughly elliptical shaped area of a dirty yellow stuff which is fissured, i.e. split into several portions. This is a typical appearance of keratin. The most common keratinised lesion we expect to see is a seborrhoeic keratosis or wart, which are often fissured.
The rest of the lesion is made up of dark greying dots and dashes. These are what i call charcoal flecks, and they represent thrombosed capillaries. They are a global feature, we can see them in the keratinised portion of the lesion a well, and here some of them are red.
Charcoal flecks represent thrombosed blood vessels, the looped vessels we see in seborrhoiec keratoses. These lesions commonly present with a history of recent change which may include itch, growth in size, bleeding, scabbing and bits falling off. They may look very alarming to the untrained eye and are very commonly referred urgently as a suspected skin cancer, since they tick several boxes for a melanoma.
NB the pinkish background across the centre of the lesion represents inflammation due to trauma. It will fade.
If the clinician is confronted with such a lesion and there are dermoscopic features pointing to a traumatised seb k and no first rank features of a melanoma, it is reasonable to photograph and review in 2 weeks.