What is this?

[marmitemania]

This mark has appeared on my step daughters arm. It's a red blotch with a darker red centre. Is it ringworm?

[juice]

Looks like a bite/sting reaction to me.

[57 Chevy]

Get a pen and draw round it, then you can see if it gets worse.

[marmitemania]

I think it may be a bite. But the good lady thinks it might be ring worm. We will draw around it.

[Cantaloupe]

This is ringworm, it has a darker edge and is generally circular.

[Saleen836]

If it itches like a good'un it 's possibly a bite from a horse fly

[Le Controleur Horizontal]

Badly applied sun cream, missed a bit ?

[Rosedene]

Could she have been bitten by a tick? If so a “bullseye” reaction could be a reason to get it checked by her GP in case of Lymes disease.