another ugly duckling and some Kittlerian dermoscopic terms
After attending the 4th world dermoscopy (and skin imaging) conference in Vienna this April, I am slowly including some of the new descriptive terminology advanced by Professor Harald Kittler and associates. For more about this I suggest checking out the excellent series of videos by Ian McColl on his ‘Dermoscopy Made Simple’ site. I highly commend these teaching videos-Dr McColl has his own style, as do I, and given the complex and somewhat subjective nature of dermoscopy for pigmented skin lesions I consider it wise to learn from multiple teachers and triangulate/compare.
Anyhow, here is a skin lesion which has appeared and grown in under a year. How are we going to approach this systematically in order to reach a safe diagnosis and management decision? Lets have a look at the plain view of this lesion.
One of the approaches discussed at Vienna, not least by Professor Peter Soyer is the ‘heuristic’ approach. This means ‘Eureka!’ or ‘I have it!’ An image of an elephant was used by several presenters to illustrate this point-one look at a picture of an elephant and you say ‘its an elephant.’. One look at this lesion and you utter an exclamation, whether ‘Eek!’ of ‘Oh ****!’. In any event, its a pretty obvious melanoma. I have seen benign lesions that looked like the plain view here but were acquitted on dermoscopy. Lets have a look at the dermoscopic view. click to enlarge.
Lets study this in the style of Kittler. What is the first thing we notice? Chaos. This is the immediate impression and a very good word, but can we make it any more systematic? How do we denote chaos in a dermoscopic image? To begin with we look for symmetry. The lesion is not symmetrical. Next we count colours-there are many. I can see black, white, blue/grey and brown (several shades). I like the term ‘too many colours’ and it certainly applies here.
Next we count structures, and this gets a little more fiddly-we need some vocabulary, and there is a big ongoing discussion about dermoscopic vocabulary Hopefully this will be settled when the new dictionary of dermoscopy comes out. Starting with the most obvious, in the top left hand quadrant we see a featureless area which is black. This can be referred to as an eccentric black blotch, or a large black clod in the new descriptive terminology. What’s the difference between a blotch and a clod? In my book a blotch is somewhat larger, say at least a tenth of the volume of the whole lesion, but that is a bit subjective.
At 3 o’clock there is what I usually call a reticular network but in the new descriptive terminology is lines reticular. This is not absolute proof but strong indication of a melanocytic lesion. Incidentally, this side-steps us to the 2 step algorithm ‘is it melanocytic? If so, could it be a melanoma?’
between 11 and 1 o’clock we see streaks, or what in Kittlerian terms are ‘peripheral lines radial’. These used to be called ‘radial streaming’ Confused? don;t be, in the end these are only words, its the structures they describe that matter. But there is a big effort being made to develop, agree and roll out systematic, internationally agreed words for particular structures, this post is me doing my bit-I’m on a learning curve too.
left of centre in the lower half we see a blue grey (or is it blue white?) veil, or what is now called ‘blue grey structureless area’. In this are shiny white streaks (used to be called chrysalis structures).
That is at a minimum 4 distinct colours (black, brown, blue and white) and 5 distinct structures (eccentric black clod, lines peripheral radial, lines reticular, blue-white structureless area and shiny white streaks). I would expect the intermediate dermoscopy learner to confidently diagnose a melanoma from that description down the telephone. The key is learning to identify and name the colours and structures systematically. I hope this post helps. I have only read about 10% of Kittler’s book so far, having used older metaphorical terms since I started dermoscopy in 2002 its a bit challenging but I’m sure is the way forward.
Never forget the elephant though. As I always tell learners, spend an hour looking at the collection of 177 plain melanoma images on dermis.net. If it looks like an elephant, there is a pretty strong chance it is an elephant, and most melanoma diagnoses will still be made on a history of recent change and one glance.