Skin colour changes on DD tummy

[PoppyPlum]

My 6yo DD, who is otherwise healthy and bouncy, has developed an issue where one half of her torso is a (slightly) different colour than the other. Essentially it is like one half has a slight tan, with a line down the middle. DH and I can't agree whether the darker or the lighter area is her natural skin colour but I think it's the lighter and the 'spot' is therefore darker.

Does anyone have an idea what this might be? It's definitely NOT a tan as her torso has not been in the sun. I'm considering taking her to the GP.

Google provides no useful answers, it looks nothing like vitiligo.

Have you heard of Chimerism? Has it always been this way?

www.livescience.com/61890-what-is-chimerism-fused-twin.html

It could be that...possibly.

That sounds pretty unlikely idea. If nothing else the only way that could happen is if they're identical twins in which case they'd have the same skin tone surely?

They do sometimes develop skin decolouration-dd2 has a line down the centre of her tummy that I noticed at around 8yo.
I would take her to be checked as very very rarely I think skin decolouration can show an underlying course (do not google, you'll always get worse case scenario) so it is worth checking.

Witch It's not an "unlikely idea" and it's quite common. Twins don't always have the same skin tone no....some people with Chimerism have differently sized hands for example...twins aren't always exactly the same.

Could be some form of hyperpigmentation

www.allure.com/story/what-is-melasma-hyperpigmentation-differences-treatments

I have a birth mark which is just a patch of skin that tans a lot more than the rest of me, and it tans really quickly.

Might it be something like that?

Always worth a trip to the gp if you're worried

Yes I'll give the GP a ring. I won't do too much googling, I think it is highly unlikely to be anything serious as she is such a picture of health with no other symptoms.

She has always had some 'pigment' things going on - she is very fair and has quite a few freckles, also has a very light brown small birthmark on her arm since birth. But these marks are tiny in comparison to half of her tummy which now seems to have changed colour.

Twins aren't always the sane, no, but in this situation you say they would have to be identical twins for whom the skin colour, barring mutations, would be the same.

And it's usual for people to have one foot/hand/ear etc bigger than the other. In some people it's quite obvious, in others it's just a small difference that you don't notice unless actively comparing.

Witch Chimerism is a lot more complex than that.

The condition occurs when one unborn child absorbs the cells of another miscarried sibling in the womb, leading to the surviving person taking some of the genes of their “ghost” twin. That can lead to strange results in the DNA of people that have the condition — but it can often go completely unnoticed.

It can show itself in variation of skin tone....not always but sometimes in different coloured eyes. It's thought to be a lot more common than previously realised.

There are several genetic syndromes that manifest with skin patches. Many are just that, an hyperpigmentation of the skin, others are a bit more annoying.I have the annoying type called NF1. Another syndrome recently discovered, Legius is also called NF1-like but is benign. McCune-Albright syndrome is somewhere in-between.

If your GP is dismissive, ask if he/she excludes these.

I was diagnosed with NF1 in my 40s. From 0-20 years, my only signs was that half my back was darker. GP and dermatologist blamed perfume and sunshine interaction (as if I would put perfume on my shoulder blade?), the bumps appeared very very slowly in adulthood. The eyes nodules were never noticed despite many visits.

KingIrving I am sorry to read about your MF1 and thank you for replying.

We've sent photos of DD's stomach area to a family member who is a GP and he thinks it is a harmless difference in pigmentation which she could well grow out of. DH is happy to leave it at that. I'm not sure where to go from here and whether to still take her to our own GP. Having looked at some websites these are not "cafe au lait" spots as such but a slight difference in colour on one side compared to the other. But I note yours was the same in childhood.

Sorry NF1

I don’t have a single CAL ( cafe au lait) , it was just a darker area, quite large and irregular. I develop kyphosis as a teenager and normally those with NF have scoliosis, so many missed opportunities to diagnose.

This said, many have darker patches and everything is fine.