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August 19, 2014 / molehunter

2 slightly odd looking moles on the back

This late middle aged white person was concerned about 2 moles on the back. They had been present for at least 10 years and there was no clear history of recent change or other worrying features.

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There are several pigmented lesions here, of which the ones at 4, 6, 7 and 12 o’clock are obvious seborrhoiec keratoses. The 2 largest and darkest are apparently melanocytic naevi. Applying the ABCD rule, they are mildly ‘wrong’ being somewhat asymmetrical, of varied colour, over 6mm diameter, and the one at 9 o’clock has an irregular shape and edge. Dermoscope time. NB please remember to click on the image to magnify it.

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These are in my opinion topographically very similar, so I will describe both together to start. Both are around 10 by 6 mm, main colour medium brown, reticular network and paler in the middle. We also see dots. As I always say about dots (and globules) when we see them we want to ask 3 questions.

1) are they similar in size?

2) are they similar in colour?

3) are they distributed in a homogenous manner? 

These dots are small, even in size and colour, and distributed fairly evenly. This isn’t anything to worry about. We do worry if dots or globules are very irregular in size, colour and distribution.

Regarding the reticular network (lines and holes), the referring doctor was concerned that this network was irregular. I wasn’t. Of course it’s not perfectly regular, but then it never is. I have posted some examples of irregular network and will post some more, but in the end you have to make a judgment. I recommend using the dermoscope to look at thousands of moles about which there is no clinical suspicion to ‘get a feel’ for normal. Ask a colleague, photograph everything you excise and check back the histology, study as many on line images as you can, it all comes.

The fact that these 2 naevi are quite similar is reassuring. 2 primary melanomas in one patient is possible, but uncommon. If a patient has several naevi that are slightly odd but similar to each other, its most likely genetic and of no importance. Beware the ONE mole that stands out dramatically from the rest, the ‘ugly duckling’.

NB the first mole is quite irregular in shape and outline. OK, that gets our attention. But the dermoscopy shows that he colour and architecture are very homogenous. That is far more important than shape. 

There are no globules, no streaks, no blue grey veil, no colours other than brown (i.e. no blue, grey, black or red) and taken with the clear history of both moles being present for 10 years plus and no recent change a 99% plus likelihood of benignity was justifiable.

However, it should be noted that some doctors would want to excise one or other of these moles to put the issue beyond doubt. All I can say is that I was clinically convinced they were both harmless, mildly atypical at worst. You can’t IMO justify the NHS cost, patient discomfort and scarring of very mildly atypical skin lesion excisions just to prove your point, nice as it would be to have histology for absolutely everything.

Diagnosis: benign compound naevi. No histology available as it was not considered necessary to excise. Photograph and review was advised, mainly for reassurance. As always, the patient was advised what changes to look out for and report.

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6 Comments

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  1. Mark Wilbourn / Aug 20 2014 9:49 pm

    My eyes are drawn to the darker 4 o’clock area of the second lesion. There is loss of the reticular network and concentration of pigment globules. Why is this not significant? Also what are the white globules?

  2. molehunter / Aug 21 2014 8:49 am

    HI Maerk. I thought someone might notice that. This area simply isn’t big enough or abnormal enough to worry about, especially since there is a slightly similar area in the other mole and these have been there for over 10 years. You need to study thousands of moles to get a feel of how much asymmetry can be tolerated, for make no mistake you will never see a perfectly symmetrical mole. Look at some of the melanomas I have posted here -click on ‘melanoma’ and ‘irregular pigment network’ in the right hand column to see some real bad asymmetry. Thanks for commenting. Also try Gooogle images search on dermoscopy + pigment network.

  3. molehunter / Aug 21 2014 8:51 am

    PS I wasn’t absolutely certain what the white globules were, Could be milia like cysts which you do see in moles (though rarely so many). Well spotted. On further study I think they are simply holes in the network. If you look, some of them have faint brown lines around them and the ones on the right particularly seem to blend in with the reticular network. Well spotted, they are a slightly unusual feature of this benign compound naevus.

  4. AmericanRecallCenter (@RecallCenter) / Aug 22 2014 7:17 pm

    Hi there, I’m Lindsey! I have a question and would love to speak with you. Please email me when you have a moment, thanks so much! Looking forward to talking to you 🙂 lindseyDOTcaldwellATrecallcenterDOTcom

  5. Jackie / Sep 9 2014 4:09 am

    Several months ago I noticed a small grayish looking, what I thought to be a scab of some kind. I picked it off and didn’t give it any more thought till a couple of days later I noticed a mole in the very same spot. I left that one alone, thought is was kind of odd but didn’t feel concerned. Within just a few days it had raised and it continued to raise slowly. I was keeping an eye on it to see if it ever changed, well it fell off about 2 weeks ago and there was another one under it. It was like the one below it had pushed it off. The new one is starting to raise now. Any thoughts on this? Have you heard of this type of mole? I do have a doctors appointment to get it looked at this week. I came across this site while trying to google information, so thought I would just ask. Thank you so much for your time!

    • molehunter / Sep 29 2014 8:31 pm

      Hi Jackie. I cannot give individual personal advice here for ethical and legal reasons, also I could not find the time. If a mole in a white adult is new, changing, irregular or just looks wrong then it is wise to get it checked. Most moles are harmless, most skin cancers are curable.

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