BENIGN BONE-FORMING LESIONS - OSTEOMA, OSTEOID OSTEOMA, AND OSTEOBLASTOMA - CLINICAL, IMAGING, PATHOLOGICAL, AND DIFFERENTIAL CONSIDERATIONS

The benign bone lesions - osteoma, osteoid osteoma, and osteoblastoma - are characterized as bone-forming because tumor cells produce osteoi d or mature bone. Osteoma is a slow-growing lesion most commonly seen in the paranasal sinuses and in the calvaria. When it occurs in the lo ng bones, it is invariably juxtacortical and may need to be differenti ated from, among others, parosteal osteosarcoma, sessile osteochondrom a, and a matured juxtacortical focus of myositis ossificans. Osteoid o steoma and osteoblastoma appear histologically very similar. Their cli nical presentations and distribution in the skeleton, however, are dis tinct: osteoid osteoma is usually accompanied by nocturnal pain prompt ly relieved by salicylates; osteoblastoma arises predominantly in the axial skeleton, spinal lesions constituting one-third of reported case s. This review focuses on the application of the various imaging modal ities in the diagnosis, differential diagnosis, and evaluation of thes e lesions. Their histopathology also is discussed, and their treatment briefly outlined.