Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Juvenile ossifying fibroma ?
    ### Response:
    Juvenile ossifying fibroma (JOF) is rare, benign tumor of the craniofacial (skull and face) bones. It is considered a "fibro-osseous neoplasm" because it is characterized by an overgrowth of bone. Affected people generally experience a gradual or rapid, painless expansion of the affected bone or region.
    