Primary bone tumors of the orbit.

Primary tumors of orbital bone constitute 0.6% to 2% of all orbital tumors. Our experience over a 24-year period in the Orbital Clinic at the University of British Columbia yielded 62 (1.9%) cases from a total of 3,340 orbital tumors. Although a heterogeneous group, primary orbital bone tumors may be classified on a clinicopathologic basis into benign fibro-osseous or cartilaginous, reactive, neoplastic and vascular disorders. Presentation is usually a gradual mass effect, with infiltration and acute hemorrhage being features of malignant and reactive lesions respectively. The two most commonly encountered entities were fibrous dysplasia and osteoma, accounting for 22 cases. Although both these conditions rarely present a diagnostic challenge, nonspecific histologic and radiologic appearances can result in poor characterization of several of the rarer lesions. Hence, close cooperation between clinician, radiologist and pathologist is essential for accurate diagnosis.