It is on the bone of her shoulder blade (not between). She is an indoor cat- the most she has been outside is for a few minutes, but this is not typical. I'm not sure where her vaccines were delivered.
Thank you for the additional information.When ever we hear of a bump in the area of the shoulder blade at the base of the neck we worry about vaccine associated Fibrosarcoma. This is a fast growing cancer that develops in that area in response to vaccines in some cats. Here is additional information LinkIt is also possible that this is something simple such as a sebaceous cyst which is nothing to worry about as it is caused by a clogged pore.LinkConsidering the location of this lump I would suggest having this looked at by the vet to be sure it is not something serious.I hope this helps. Please reply back if you have additional questions or concerns and I will be happy to continue.Candysebaceous cyst