Most of the hard bones bulging from the forehead are localized osteoma, located in the outer plate of the skull, bulging outward to form a local high convexity, no obvious changes in the local skin, no varicose veins, no redness or swelling, no obvious pain when pressing the local area, and not moving when pushed. The growth is generally slow and malignancy rarely occurs. Generally, no treatment is needed, and the size of the developing tumor should be closely observed. If the tumor suddenly increases in size or presses on the orbit or intracranial structures, clinical symptoms may arise and surgical treatment is required. In conclusion, it is important to seek medical attention for a clear diagnosis when a hard forehead bump is found.