The parents of a 14-year-old girl brought her to a dentist, complaining that she has some kind of growth on her tongue. It appeared approximately 1.5 years ago and has been slowly growing since then. Objectively, on the lateral surface of her tongue there is a neoplasm on the left. It is pink, mobile, painless, hard, and spherical. It has clear margins, wide base, and smooth surface. Make the provisional diagnosis: