Bilateral osteonecrosis of the external auditory canal caused by bone-modifying agents for cancer bone metastases.

A 51-year-old woman with a 54-month history of treatment with bone-modifying agents for thyroid cancer bone metastases, namely zoledronic acid for three months and denosumab for 51 months, presented with jaw pain, trismus, and ear discharge. Physical examination, bacterial culture, and radiological findings led to a diagnosis of osteonecrosis of the external auditory canal. Since the discontinuation of denosumab did not improve the diagnosed condition, she underwent surgical reconstruction. Bone-modifying agents such as zoledronic acid and denosumab, which are commonly used to prevent skeletal-related events in patients with bone metastases from various cancers, have been used for several years, especially for patients with slow-growing cancers. Osteonecrosis of the external auditory canal is an infrequent but serious adverse event caused by prolonged use of bone-modifying agents. Therefore, clinicians should be fully aware of its potential risks in the long-term management of bone metastasis.