Case Report: Incidental Finding of an Osteoblastoma of the Mandible

Abstract

Osteoblastoma is a rare, benign primary neoplasm of the bone. The reported incidence rate of osteoblastomas is 1% of all whole body bone neoplasms. According to radiologic literature, this entity is most commonly reported in the vertebral skeleton. Of these reported lesions, 15% arise in the gnathic skeleton, 36% occur in the vertebrae with the remaining in the long bones of the extremities.1 Osteoblastomas have a predilection for presenting in the second or third decade. Seldom these lesions occur at a more advanced age.2 This entity appears to affect males more frequently than females, with a gender predilection of 2:1. Among reported cases arising in the gnathic skeleton, medullary bone is the primary location. The hypothesized pathogenesis involves benign neoplastic proliferation of osteoblasts.1Clinically, osteoblastomas often present as a painful swelling of the mandible. Imagining of this entity may be variable with a differential diagnosis spanning both benign and malignant neoplasms. Often radiographic features include ossification with an increase in radiodensity.2 Additional radiographic characteristics may include sclerotic bone with a radiolucent halo. This presentation is similar to an osteoid osteoma. Histopathology of this entity includes anastomosing trabeculae set within a loose fibrovascular stroma.2 Key histologic features include osteoblastic rimming with varying degrees of calcification. Definitive diagnosis may be challenging because of the similar histological features seen with primary malignant bone neoplasms, especially osteosarcoma.2Traditionally, the treatment involves surgical intervention, which ranges from aggressive curettage to en-bloc resection. Reported surgical intervention is dependent on size and anatomic location. Recurrence of the entity is reported to be uncommon with a 20% recurrent rate. Malignant transformation secondary to radiation therapy has been reported.1The authors present the clinical course and treatment of a 68-year-old male who presented to the St. Barnabas Hospital Oral and Maxillofacial Surgery Clinic for evaluation and treatment of a painful mobile carious tooth. On review of his panoramic radiograph, an incidental finding of a lesion was noted in the lower left mandible. The patient complained of no pain in the left mandible, and clinical examination showed a mild lateral expansion of the lower left mandible. The radiographic examination was consistent with a well-defined radiolucent/radiopaque lesion of the left mandible below the inferior alveolar nerve canal. The patient underwent an incisional biopsy in the operating room and was subsequently diagnosed with an osteoblastoma.