Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Figure Caption
Osteoma is a common benign tumor, occurring most frequently in the frontal sinus (80%), followed by the ethmoid sinus (15%). The tumor is known to be associated with Gardner syndrome. Most osteomas are small in size, while some are large and may encroach upon the brain by eroding the dura, causing CSF leak, pneumocephalus, or meningitis. More frequently, the bone tumor may impair normal drainage of paranasal sinuses, resulting in sinusitis or mucocele formation (red asterisks). Ivory osteomas are composed only of cortical bone, whereas mature osteomas resemble “normal” bone, with cortical (yellow arrows) and marrow space (green arrows). MRI can mislead and result in an incorrect diagnosis, especially in mature osteomas, because the tumors may have areas of high T2 signal and may even enhance.