title: Value of fused positron emission tomography CT in detecting primaries in patients with primary unknown cervical lymph node metastasis.
abstract: OBJECTIVE
  Identification of the primary tumour can prolong the life expectancy of patients with primary unknown cervical lymph node metastasis (PUCLNM) through targeted therapy. This study investigated the value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET-CT) at identifying primaries in patients with PUCLNM.
  
  
  METHODS
  Twenty-seven patients (21 males and 6 females, median age 48.2 ± 16.3, age range 30-73) with PUCLNM underwent FDG PET-CT to search for the primary tumour, which could not be detected by conventional diagnostic modalities. The results were analysed and correlated with either pathological findings or clinical follow up.
  
  
  RESULTS
  Pathological FDG uptake suspicious for the primary was detected in 13 cases, while the primary tumour remained occult in 14 cases. Eleven of 13 patients with suspected primaries were confirmed by histological findings. One with a coexisting second tumour and three with unexpected distant metastases were found in patients with confirmed primaries. The most common primary location in patients with PUCLNM found in our study was nasopharynx. In those 14 patients with negative FDG PET-CT results, only one patient had a primary malignancy that was proven histologically after endoscopy with biopsy during a period of clinical follow up. The sensitivity, specificity, accuracy and positive predictive values of FDG PET-CT were 91.7, 86.7, 88.9 and 84.6%, respectively.
  
  
  CONCLUSIONS
  FDG PET-CT is a useful tool to help search for unknown primaries in patients with cervical lymph node metastasis and has an acceptable diagnostic yield for the detection of distant malignancies.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Yue-Hong
authors.initials: YH
authors.lastname: Chen
authors.forename: Xin-Ming
authors.initials: XM
authors.lastname: Yang
authors.forename: Shi-Sheng
authors.initials: SS
authors.lastname: Li
authors.forename: Yuan-Hua
authors.initials: YH
authors.lastname: Wang
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: He
authors.forename: Yi-Da
authors.initials: YD
authors.lastname: Yang
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.forename: Jia-Jia
authors.initials: JJ
authors.lastname: Liu
authors.forename: Xiao-Li
authors.initials: XL
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D004724:Endoscopy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D061305:Lymphoscintigraphy; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009382:Neoplasms, Unknown Primary / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D011860:Radiography, Abdominal; D013902:Radiography, Thoracic; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18