Bisphosphonate-Related Osteonecrosis of the Jaw Mimicking Bone Metastasis

Osteonecrosis of the jaw is usually a potential complication of bisphosphonate therapy. In a cancer patient, this disease entity can be misdiagnosed as a metastatic lesion. Our aim is to make clinicians aware of bisphosphonate associated osteonecrosis of the jaw to prevent misdiagnosis and initiate proper treatment at the earliest. We present the case of a breast cancer patient with multiple bony metastases and a jaw lesion presumed to be metastases. After no response to palliative radiation, repeat radiological imaging studies revealed osteonecrosis of the jaw. Correlating a patient’s clinical information with findings on diagnostic imaging studies, such as SPECT bone and CT scans, can help identify this potential complication of bisphosphonate treatment. Early diagnosis helps minimize unnecessary biopsies and allows for the proper treatment to be instituted. 1. Introduction Bisphosphonates are now part of the standard treatment for bone metastases and hypercalcemia of malignancy; their use decreases the incidence of skeletal related events and improves the quality of life [1]. Although the incidence of osteonecrosis of the jaw (ONJ) in the general population is unknown, among cancer patients with metastatic bone disease treated with bisphosphonates it is as high as 10% [2, 3]. The clinical and radiological presentation of bisphosphonate- related osteonecrosis of the jaw (BRONJ) could be mistaken for a bone metastasis [4]. An understanding of the risk factors, preventative measures, early diagnosis, and treatment of BRONJ are thus necessary. 2. Case A 61-year-old African American female was diagnosed with left breast cancer with multiple bone and liver metastases in April 2009. She was treated with chemotherapy and intravenous bisphosphonate therapy with zoledronic acid. A follow-up bone scan redemonstrated the multiple bone metastases, now with a new focus of increased radiotracer activity in the left mandibular angle. Radiological interpretation suggested that this focus most likely represented either severe dental disease or a metastatic focus. Few months later, the patient developed severe pain in her mandible, for which dental evaluation led to a tooth extraction. However, following the tooth extraction, the patient’s jaw pain progressed with worsened swelling of the left lower jaw. CT scan of the mandible (Figure 1) demonstrated a mandibular body bony lesion on the left with adjacent soft tissue stranding, again interpreted to be concerning for a metastatic bone lesion. Bone scintigram (Figure 2) demonstrated expansion of the mandibular lesion