Atypical multiple benign osteoblastomas accompanied by simple bone cysts. A case report.

A case of atypical benign osteoblastomas occurring at multiple sites in the maxilla and mandible of a 38-year-old woman, in association with simple bone cysts, is described. The tumors produced hazy or ground-glass-like semiradiolucent lesions with well-defined or poorly-defined margins on conventional radiographs. Histologically, the lesions were characterized by a proliferation of plump osteoblast-like cells forming trabeculae of osteoid and immature bone in a well-vascularized stroma. In addition, simple bone cysts associated with a radiolucent-radiopaque lesion consisting of lamellar bone and loose connective tissue were found next to one of the tumours. Possible pathogenesis of the tumours and cysts is discussed.