Aggressive osteoblastoma of the mandible closely simulating calcifying epithelial odontogenic tumor - Report of two cases with unusual histopathologic findings

Aggressive osteoblastoma is a rare bone-forming neoplasm composed of promin ent epithelioid cells that demonstrate locally invasive growth with a high rate of recurrence but no metastatic potential. Clinical, radiographic and pathologic features of mandibular aggressive osteoblastoma in a 21-year-old African-American male and a 12-year-old Caucasian female are presented. Bo th tumors were resected with wide surgical margins and neither patient had adjuvant radiation or chemotherapy. The patients showed no evidence of loca l recurrence or distant spread either clinically or radiographically after two years of follow-up. These tumors were composed of solid sheets of pleom orphic epithelioid cells, eosinophilic amorphous osteoid with foci of calci fication, which closely simulated amyloid. Differentiation of this tumor fr om histologically similar calcifying epithelial odontogenic tumor and low-g rade osteosarcoma proved difficult. Immunohistochemical study with osteocal cin confirmed the osteoblastic nature of these epithelioid cells.