A biopsy means something needs to be looked at under a microscope. Therefore, a surgical procedure is needed to send in a sample to the lab for study. There are two types of biopsies.  If the area to be looked at is small then the whole thing can be removed.  If the area of concern is big than a small piece is removed and sent in for study. Once the tissue is looked at then a diagnosis can be made. There are many odd things that can grow in the mouth. Most of them are not cancer. The Oral Surgeon is the specialist often called upon to do the surgical procedure known as the biopsy.