OBJECTIVE: A large series of patients with pathologically proven osteoid osteoma of tubular bones was reviewed to determine the frequency of a subperiosteal site of origin. MATERIALS AND METHODS: Thirty-eight cases that were included met two criteria: the tumor was located in a tubular bone, and the lesion had been evaluated by CT scanning or MR imaging, or both. The location of the osteoid osteoma was categorized as intracortical, sub-periosteal, endosteal, or medullary. RESULTS: Among the 38 cases, 19 were imaged with CT scanning, 14 with MR imaging, and five with both techniques. The most common affected sites were the femur (n = 13), tibia (n = 15), and humerus (n = 4). Among these 38 cases, 18 were intracortical, two were intramedullary, and 18 were subperiosteal. CONCLUSION: Osteoid osteomas occurring in a subperiosteal or surface location are not rare. Indeed, many osteoid osteomas arising in a tubular bone possibly originate in a subperiosteal site and later appear as an intracortical lesion. This site of origin appears to relate principally to continual remodeling of bone with subperiosteal deposition and endosteal erosion.
OBJECTIVE: A large series of patients with pathologically proven osteoid osteoma of tubular bones was reviewed to determine the frequency of a subperiosteal site of origin. MATERIALS AND METHODS: Thirty-eight cases that were included met two criteria: the tumor was located in a tubular bone, and the lesion had been evaluated by CT scanning or MR imaging, or both. The location of the osteoid osteoma was categorized as intracortical, sub-periosteal, endosteal, or medullary. RESULTS: Among the 38 cases, 19 were imaged with CT scanning, 14 with MR imaging, and five with both techniques. The most common affected sites were the femur (n = 13), tibia (n = 15), and humerus (n = 4). Among these 38 cases, 18 were intracortical, two were intramedullary, and 18 were subperiosteal. CONCLUSION:Osteoid osteomas occurring in a subperiosteal or surface location are not rare. Indeed, many osteoid osteomas arising in a tubular bone possibly originate in a subperiosteal site and later appear as an intracortical lesion. This site of origin appears to relate principally to continual remodeling of bone with subperiosteal deposition and endosteal erosion.