If there is a bone protruding from the forehead, the more common cause is osteochondroma or bone cyst, and it may also be other masses. You can go to the hospital and see a doctor, who will make a preliminary judgment based on the physical examination. For example, whether the localized protrusion can be pushed, if it cannot be pushed then it is considered to be a bony mass. If it can be pushed, it may be a soft tissue mass such as a lipoma, which feels like a bone protrusion. The nature of the localized bony protrusion can be determined by CT of the head and 3D reconstruction of the skull. If it is a bone cyst osteochondroma, it is usually a benign lesion. It can be followed up and observed, or it can be removed by local surgery, and if it is large in extent, bone grafting is needed if necessary.