It develops in the bone and grows to a certain size but then stops growing and does not destroy the bone like an active or aggressive benign bone tumor. It stops growing and does not grow uncontrollably. They tend to cause a weakness in the bone depending on the size. They may need to be treated to prevent the bone from breaking or treat an actual fracture through the tumor. In many instances these types of tumors are observed. When treated they rarely if ever come back.