Osteoblastoma in the mandible of an older adult patient without FOS gene rearrangement: A case report and literature review

Osteoblastoma is a benign bone tumor with predominance in those < 20 years of age and rarely occurs in the maxillofacial region. The identification of FOS gene rearrangements in osteoblastomas has been reported, however, a small subset of osteoblastomas do not show FOS gene rearrangements. There are no reports discussing the relationship between age and FOS gene rearrangement in osteoblastomas. We report the case of a 66-year-old female patient with histological features of osteoblastoma in the mandible without FOS gene rearrangement. According to a review of previously reported cases of osteoblastoma, FOS gene rearrangement is significantly less common in patients > 40 years of age (P = 0.041). Osteoblastomas occurring in older adult patients may exhibit pathogeneses different from those of young patients. Further data, including the relationship between age and FOS gene rearrangement, is necessary to clarify the pathogenesis of osteoblastoma.