Medication-related osteonecrosis of the jaw with severe soft tissue necrosis associated with osimertinib therapy.

Osimertinib, an epidermal growth factor receptor tyrosine kinase inhibitor, improves the progression-free and overall survival of patients with inoperable or recurrent non-small cell lung cancer. However, it is reportedly associated with osteonecrosis of the jaw and oral mucositis due to its ability to reduce osteoclast differentiation and inhibit angiogenesis. A 73-year-old woman had been receiving osimertinib for recurrence after lung adenocarcinoma surgery; 3 years later she presented with bone exposure and buccal mucosal necrosis. After the clinical diagnosis of medication-related osteonecrosis of the jaw with soft tissue necrosis, osimertinib was discontinued. Four months after discontinuing osimertinib, she underwent hemimandibular resection and immediate fibular graft reconstruction under general anesthesia. Eight months postoperatively, the wound had healed, and graft ossification was satisfactory. This case highlights that osimertinib may be linked to osteonecrosis of the jaw and soft tissue necrosis. When discontinuing osimertinib, close cooperation between cancer physicians and dentists is essential, given the potential for underlying disease progression.