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May 24, 2012 / molehunter

Another ugly duckling

The term ‘ugly duckling’ is often used to denote a skin lesion that looks different to and stands out from the patient’s other pigmented lesion. It sticks out like a sore thumb. A great many melanomas are detected like this, you should always trust your gut instinct if a mole that is changing looks wrong. If it looks wrong, it often is.

This patient has 30 or so pigmented lesion on his back. One of them stands out as darker and bigger than the rest.

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a close up reveals some asymmetrical colour. Nothing really dramatic though.

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The dermoscope reveals an asymmetrical black blotch (circled) with more than a hint of blue-white veil, plus peripheral streaks, globules and pseudopods (arrowed in final image) especially between 3 and 6 o’clock. Note also the group of 3 or 4 pseudopods/peripheral globules at 12 o’clock.

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My views on pseudopods are a little heretical, in that I don’t see any meaningful distinction between them and peripheral streaks and globules, so I tend to lump these structures together. Both dermoscopic structures represent nests of proliferating melanocytes in dermoscopical-histological correlation. So when is a peripheral globule a pseudopod? If any more expert dermoscopist can explain how to tell them apart and why it matters, I’ll be delighted to post a correction. The important thing is that when you see this kind of structure ASYMETRICAL and PERIPHERAL, it is highly suspicious, especially in a new or growing lesion in a patient over the age of about 25.

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IMPRESSION-probable melanoma

ACTION urgent referal for excision

Melanoma was confirmed. A thin and hopefully curable lesion.

REFLECTION

A lesion that looks like this to the naked eye, especially if there has been a recent history of change, deserves dermoscopic evaluation without delay by someone who knows what they are looking at. Many such lesions will be benign, but you can’t say that from the naked eye view here, certainly not from the first image. The dermoscope will acquit many lesions that look as dark and different as this when clear cut features of a benign lesion, typically a seborrhoiec keratosis, are seen. The globules and black blotch here point to a melanocytic lesion. If melanocytic, and not benign, then a melanoma.

This is one of 50 cases that will be on the virtual textbook given to learners on our new course, see earlier post for details

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