The Role of 18F-FDG PET/CT for Evaluation of Cervical Metastatic Lymph Nodes in a Patient with Metallic Artifacts from Dental Prosthesis: a Case Report.

Cervical metastasis of squamous cell carcinoma from an unknown primary site occurs in approximately 2-4% of head and neck tumor cases. Without identification of the primary site, proper management cannot be achieved, resulting in significant morbidity and a lower cure rate. For the primary site assessment, positron emission tomography/computed tomography (PET/CT) using the radiotracer 18F-fluorodeoxyglucose (FDG) is the imaging modality of choice and has been shown to be superior to CT alone. Here, we report a case of cervical metastasis of squamous cell carcinoma in an 82-year-old man. 18F-FDG PET/CT revealed a tongue-base lesion, although neck CT detected no lesions because of artifacts from dental prosthesis, which was suspected as the primary site. The final diagnosis was confirmed as tongue-base cancer with neck lymph node metastases through biopsy. These results suggest that 18F-FDG PET/CT is a valuable diagnostic tool in patients with cervical metastatic lymph nodes because it can demonstrate primary tumors in patients with dental prosthesis.