Thanks for the additional information. First of all, I can only tell you what this might be. Even if you were sitting in front
of me and I could see the lesion, I still wouldn't know exactly what it was, nor would any dentist
without taking a tissue sample of the area and having it evaluated under a microscope. The oral pathologist doing the evaluation would then be able to tell you exactly what these cells represent.
With that in mind here is how I would evaluate the lesion.
Dark blue usually suggests a vascular lesion, such as a congregation of venous blood vessels near the surface of the tissue. To tell or not, push on the blue spot with your finger and then carefully look at the color of the spot as you quickly take your finger off the lesion. If it is vascular in nature, the color of the lesion will be white or pink for a moment before it fills up with blood again and turns back to the blue color.
Vascular lesions are normally not a cancer, but should be removed by an oral surgeon as they have the potential to get poked at or scraped in the future causing quite a nasty bleeding spell. Besides, the lesion doesn't belong there, better to have it removed.
If the color doesn't change when pressing on it, then you have to determine if the lesion is raised or not. Does it elevate above the base level of the skin in that area.
As large as a lesion you describe, an inch in diameter I doubt this is a freckle or even a wart like lesion. This could be something simple such as a bruise caused by a recent suction applied to your mouth, such as trying to suck something thick through a straw, such as a thick milkshake. THis action will break the blood vessels and cause such a discoloration. And, unfortunately, this large a lesion may suggest some underlying medical condition, disease or blood disorder.
You need to have an oral surgeon take a look at this as he/she will have more experience with oral lesions as compared to your general dentist. You can find the nearest oral surgeon to you by following this link:http://www.aaoms.org/findoms.php
I hope this answers your question. If you would like to discuss this further or have any additional questions, please reply to my answer and I will get right back to you.
Sincerely, XXXXX XXXXX DDS