I had a dental check up today. They hygienist & dentist pointed out an area about the size of a penny or slightly smaller on the left side of the roof of my mouth, way at the back. The recommended watching it a month to see if it changes or going to have a biopsy. I am very nervous now about mouth cancer. What could this purple spot be? Could it be cancer?
Given what you have described (including the color purple in your title), the most common or most likely possibility would be a bruise-like area just below the skin (mucosa) surface on the roof of the mouth. Waiting on a biopsy is probably not a bad idea. But since you are obviously concerned, I might suggest that you ask your dentist to re-examine the area in 2 weeks, rather than waiting a month. While it is difficult to totally exclude the possibility of cancer, it is unlikely.