An osteoma (plural: "osteomata") is a new piece of bone usually growing on another piece of bone, typically the skull. It is a benigntumor.
When the bone tumor grows on other bone it is known as "homoplastic osteoma"; when it grows on other tissue it is called "heteroplastic osteoma".
"Osteoma cutis" (also known as "Albright's hereditary osteodystrophy")
"Osteoid osteoma": An osteoid osteoma is a small benign lesion that can occur in any bone of the body, but is most frequently found in the leg. Another common location is the spine, where the tumor may cause a painful type of scoliosis. Osteoid osteomas typically affect teenagers and young adults, and are more prevalent among males than females. The tumors produce excess bone and secrete pain-causing prostaglandins, resulting in intense pain that is especially pronounced at night, when it can awaken the patient from sleep. The pain is temporarily well-relieved by aspirin or ibuprofen, but surgical intervention is usually necessary for complete palliation. Some osteoid osteomas can be treated by a less-invasive procedure known as radiofrequency ablation, but this procedure is ill-suited for tumors in areas such as the hand or spine, as it involves heating the tumor to a high temperature that may cause damage to nerves in the surrounding area. Osteoid osteomas may spontaneously resolve without treatment, but there is currently no way of detecting if and when this is likely to occur.