A question regarding my six year old siamese Bortai who is pictured in my Gallery, and some background:

She was fixed two years ago when she was four--she is a very non-vocal siamese so it wasn't urgent, but I decided to do it when I got my other siamese Chula. Now, I have read that females may get tumors or lumps near their mammary glands if not fixed at a young age, but wouldn't that occur prior to her being fixed, rather than two years later?

She is in all ways acting and eating normally, but six days ago when I was giving her a thorough petting, I found a very small lump just to the right of one of her nipples--it is about half the size of a pea, and was definitely not there the day before. It doesn't seem to pain her at all, and doesn't seem to be connected to the underlying tissue so far as I can tell. It has not grown since I discovered it, as I am checking her several times a day now. She is also not licking or biting at the area. She had bloodwork at the time of her spaying, and every test came up fine, and she was vaccinated for rabies and had her other shots then.

My question is: is this a possible tumor, or could it be some sort of insect bite which will go away?

Chula also had her spaying, rabies and shots renewed last year. The two are strictly indoor cats, and have had no contact with other animals.