Recurrent Osteoma Overlying a Methylmethacrylate Bone Cement Cranioplasty: A Rare Case.

Osteomas are generally benign tumors of the skull that affect all age groups and are diagnosed in the fourth or fifth decade of life, and are rare in childhood. Surgical resection is curative and malignant transformation is very rare. A 12-yearboy who had undergone a craniotomy for resection of a parietal osteoma four years ago, followed by a cranioplasty with methylmethacrylate bone cement, presented to our clinic with an expanding mass overlying the cranioplasty. Upon reoperation, the mass was totally excised, and the parietal cranial defect was repaired using methylmethacrylate bone cement. On histologic examination, the mass was found to be a recurrent osteoma overlying the methylmethacrylate bone cement. In this report, we discuss the etiologies of recurrence of osteoma and treatment options of these rare cases. We believe that this recurrence resulted from contamination of the surgical area and cranioplasty materials with osteoma material. Extensive washing of the cranioplasty materials and perioperative area may prevent recurrence of such tumors.