Dry, Scabby Lump

[Sue67]

Indy's got a dry, scabby lump, about the size of marrowfat pea, just under the middle of her shoulder blades. It sort of comes and goes but each time it comes, it seems to be getting slightly bigger.

It doesn't seem to bother her at all and her skins always been on the dry side.

Anyone experienced anything similar? She's due her booster soon so I'll definitely get the vet to check it.