Narrow band imaging endoscopy for unknown primary tumor sites of the neck

BACKGROUND: Examinations used to search for unknown primary tumors of squamous cell carcinomas of the neck include CT, MRI, laryngoscopy, gastrointestinal endoscopy, and positron-emission tomography (PET). Narrow band imaging (NBI) endoscopy in which an optical color-separation filter is used to narrow the bandwidth of spectral transmittance is also used. METHODS: Twenty-eight patients in whom primary squamous cell carcinomas could not be detected with conventional white light laryngoscopy underwent NBI endoscopy and PET. RESULTS: Primary lesions were detected with NBI endoscopy in 3 patients, but no primary lesions were detected with PET. However, PET was used to detect a lower gingival cancer and a palatine tonsillar cancer. CONCLUSION: Both PET and NBI endoscopy is effective for detecting unknown primary tumors of squamous cell carcinomas of the neck.