Aggressive psammomatoid ossifying fibromas (APOFs) represent a subgroup of related fibro-osseous lesions that appears to be unique to the nasal cavity, paranasal sinuses, and orbit. These rare lesions are characterized by distinctive histomorphologic features and a tendency to affect younger patients. Histologically they are benign, but clinically they are locally aggressive. We report the case of a 15-year-old boy who had a large APOF in the left ethmoid and sphenoid sinuses. The location of this tumor made this case unusual.