Abstract Juvenile aggressive ossifying fibroma (JAOF) is a rare variant of ossifying fibroma. Conventional ossifying fibromas are slow growing neoplasms thought to originate from osseous mesenchyme, commonly arising in the mandible. Conversely, JAOF occurs more frequently in the paranasal bones with rapid growth leading to local destruction, facial asymmetry, nasal obstruction, and proptosis. JAOF has two microscopic variants, psammomatoid and trabecular. Most JAOFs occur in patients less than 12-years-old with slight male predominance. We present an 18-year-old female with facial asymmetry for two years duration and recent onset of severe headaches. Examination revealed a bulging left maxillary bone and left upward proptosis. MRI showed an 81.2 × 44 × 39 mm, lobulated, well-defined, expansile osseous lesion with calcified matrix and soft tissue component involving the left maxillary sinus with extension into the left nasal cavity, frontal and ethmoid sinuses, and left orbit. An endoscopic biopsy procedure was performed to reveal sinonasal mucosa infiltrated by a cellular, fibro-osseous neoplasm consisting primarily of numerous, closely packed, round, uniform basophilic psammoma bodies with eosinophilic rings, interspersed by cellular, benign fibroblastic proliferations. Cystic changes and foci of necrosis were also noted. Complete excision of the JAOF is critical as recurrence and corresponding complications may develop in up to 50% of patients.