Any idea how long it's been like that? It looks like the scale is removed. I don't think she rubbed something in the enclosure because that would leave a larger wound. It's peculiar that it's just one scale, though the one underneath to the right seems affected as well. The shape reminds me of a tick wound, but I haven't seen a one on a snake so I can't say if that's what caused this.

I recommend a vet exam. The color and the purulent material around the edges make me worry about infection. A sample should be taken and I expect them to determine that the area requires debridement. They'll also provide a cream for the wound and anything else needed. Since she's new to you it would be a good idea to get a full exam with a cloacal culture.

Thank you for answering. A week ago i took her to the vet, due to the mite infestation. We used Neem Oil to get rid of mites, and i was soaking her aswell. Cage was cleaned with hot water and let to cool before putting the snake back in. I remember that i showed the scale to the vet, thinking that it was a mite, and he checked with tongs, maybe it was damaged at that point.

I was scared that it could be scale rot (never had any experience with it). I will take her to the vet again. Cloacal exam was done on all of my snakes, except on a pair of GTPs that i got less than a month ago (they are wild caught, in captivity since december 2014). I wanted to let them aclimate, before doing it.

You're on top of things miles ahead of most people! You're taking great care.

I may be way off and it could just be a strange scab if a scale was ripped out, but it's impossible to tell from a photo. I have seen abscesses on the stomach of an animal that caused the tissue at the surface to die and turn black, and that's what I was reminded of when I saw this, but I think it's too small to be that.

Scale rot is one of the things you rarely have to worry about with a GTP because they're arboreal. It presents as a brown color while making the skin appear mottled, and it occurs on the underside.

I haven't used neem oil with reptiles so I'm not sure of its effectiveness. If you find that you still have mites, it could be a good idea to invest in some Provent-a-Mite, but it's only for use on the enclosure and not on the animal. Natural Chemistry's 'Reptile Spray' is very well reviewed for killing the mites that are actually on the animal. I'd have both of them on hand for the next time you have to deal with a similar situation because they'll make it easier on you.

Good luck! Hope it's just something simple.

Thank you for compliment. Yeah, the picture isnt the best, but even with magnyfiying glass I cannot tell what it is :) I have seen tissue falling off, because of dermatitis, which wasnt treated at the right time, thats why i got worried.

Thank You for explaining. I decided to use Neem Oil, because it is natural product, natural antiparasitic. It was quite effective. The vet said that i have to wait 10 days before aplying it again. I wouldnt like to use something like Biokill, which it verry efective with mites, but it is not good for the snake. I will do some research on those two products, thanks for the tip (i am from Europe, maybe its hard to get them here).

Once again thank You for all your answers and help.

When a scale grows back, it doesn't always come back the same color as it was previously. It could be as simple as that. I'd just keep an eye on it for signs of infection, but I don't personally see anything concerning.

Thank you for answering, I will keep an eye on it and get her to the vet.

I agree with Sonja.

The vet said that it is necrotic scale, didnt do anything about it tho... 

He said that i should keep an eye on it.

Thanks for the update!