Non-small-cell lung cancer metastasis to the oral cavity: A case report.

We herein report an unusual occurrence of lung cancer metastasis to the oral cavity, reflecting the progression of the primary malignancy. A biopsy of oral lesions should always be performed, even of those located in uncommon sites, in patients with a history of uncontrolled lung cancer. Although this is a rare occurrence, our patient exhibited characteristics suggestive of oral metastasis from lung cancer, namely presence of lung adenocarcinoma, development of oral metastasis during the clinical course of the disease, accompanying multiple metastatic lesions, including to the brain and abdomen, and rapid fatal progression after the manifestation of oral metastasis. It is important to acknowledge the possibility of metastasis to the oral cavity in lung cancer patients with extensive metastases. Prompt diagnosis by biopsy of the lesion is required to establish the correct diagnosis.