Objective: We present a unique case of a recurrent osteoma within a cranioplasty performed with calcium phosphate bone cement.
Clinical presentation: The patient is a 7-year-old boy who had initially undergone a craniotomy for resection of a frontal cranial tumor followed by a cranioplasty with artificial bone matrix. On routine follow-up evaluation 2 years later, the patient had a mass expanding from the cranioplasty.
Intervention: At the time of reoperation, the patient was found to have a histopathologically confirmed recurrent osteoma within the artificial bone matrix. The patient later underwent repair of the frontal cranial defect using a patient-specific implant.
Conclusion: We discuss this unusual case, treatment, and possible causes. We believe that a safety margin and curettage of the resection border as well as resection of the overlying periosteum might prevent recurrence.