Rationale: Although metastases to the oral and maxillofacial region (OMR) are rare, the lung is the most common primary site metastasizing to the OMR.
Patient concerns: An 83-year-old woman presented with reports of trismus, occlusal discomfort, swelling, and spontaneous pain in the right buccal region. Despite the absence of abnormal chest imaging findings, immunohistochemical analysis of biopsy specimens of the mandible and the thyroid indicated that the patient had multiple metastases from a lung poorly differentiated adenocarcinoma.
Diagnoses: Metastases to the OMR and the thyroid from an undiscovered lung adenocarcinoma.
Interventions: Gefitinib was started as first-line chemotherapy, and zoledronic acid was administered for bone metastases.
Outcomes: Follow-up imaging examinations showed ossification and deformation of the right mandibular ramus and the condylar process. Although 2 years have passed since the first visit to our hospital, lung lesions have not been confirmed by imaging examinations.
Lessons: Clinicians should consider the possibility that symptoms in the OMR may be the first clinical sign of an undiscovered distant primary tumor, and the primary tumors may not be detected by imaging examinations even when metastases to the OMR are revealed.