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July 21, 2013 / molehunter

pigmented lesion on back

A man about my age consulted after seeing his GP for a lesion on the back which had been noticed to change gradually over about a year. As discussed, it is often difficult to be sure about lesions on the back. Where the presenting lesion is not very dramatic on plain view I have arrowed it.

july 19 case (3)

Close up.

july 19 case (2)

It is still not too dramatic although we can see it is dark and irregular.
An unattractive if not truly ugly duckling.

How worried are you about the plain view of this lesion on a scale of 1 to 10? (1=totally harmless, 10=definite melanoma).

Now lets see it through the dermoscope.


We can see some fabric debris which is of no significance beyond suggesting some surface erosion. Clothing fibres stick to scab. In the lesion, there is a clear cut blue white veil and very irregular globules. Also some weird network around 7  o’clock.

Both of the above features are highly suspicious.

Brown or black globules are highly indicative of a melanocytic lesion. You can see globules in some BCCs, but there will almost invariably be other BCC positive features such as pink background, micro ulcers and arborizing vessels. There are no such features here, therefore the globules establish this as a melanocytic lesion. Having established this [remember the 2 step algorithm i.e. (1) melanocytic or non melanocytic?, (2) if melanocytic, benign or malignant?] we must then ask ‘could it be a melanoma?’, or turning the question round ‘Can I say with confidence that this melanocytic lesion is benign?’ Not with a blue white veil you can’t.

On globules, when we see them we need to ask three questions. What colour are they, what size, and how are they distributed in the lesion? An even ring of similar sized medium brown globules is reassuring. Globules of various sizes and colour are suspicious, especially when irregularly distributed. The globules here are highly asymmetrical in size and colour and distributed eccentrically.

No option but excision, which was done immediately. Histology confirmed a thin 0.5 mm (therefore almost certainly curable) melanoma.


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