title: 18F-FDG PET/CT to differentiate malignant necrotic lymph node from benign cystic lesions in the neck.
abstract: OBJECTIVE
  Patients presenting with cystic lesions in the neck without obvious signs of malignancy constitute a diagnostic challenge since fine needle aspiration is often insufficient and a diagnosis may not be reached until surgical resection/biopsy is performed. The differential diagnosis of a cystic cervical mass comprises a variety of benign conditions, but malignancy must be ruled out. We examined the diagnostic performance of fluorine-18 fluorodeoxyglucose (18F-FDG) PET/CT to identify malignancy.
  
  
  METHODS
  We retrospectively included consecutive patients referred from the Department of ENT Head and Neck Surgery for18F-FDG PET/CT-scans because of a solitary neck cyst. Scan results were compared to histopathology and follow-up.
  
  
  RESULTS
  The study comprised 58 patients. Twenty patients (34%) were diagnosed with cancer during follow-up. PET/CT suggested malignancy in 34 patients (19 true positive, 15 false positive) and showed no malignancy in 24 (23 true negative, 1 false negative). The sensitivity, specificity, accuracy, positive and negative predictive values were 95% (76-99%), 61% (45-74%), 72% (60-82%), 56% (39-71%), and 96% (80-99%), respectively (95% confidence intervals in brackets). The primary tumor was identified in 14 out of the 20 patients with confirmed cancer. Increased metabolism, as evaluated by PET, was the only imaging characteristic among several others, which associated independently with malignancy in the cystic neck lesions, odds ratio 1.27 (1.07-1.50), p = 0.006.
  
  
  CONCLUSIONS
  18F-FDG PET/CT could reliably rule out malignancy (NPV 96%), albeit with a high frequency of false positive scans, requiring further diagnostic work-up. Increased metabolism was the best imaging parameter to differentiate between malignant and benign lesions.
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Søndre Boulevard 29, 5000, Odense C, Denmark. pey.abadi@gmail.com.
authors.forename: Peymaneh
authors.identifier: http://orcid.org/0000-0002-5678-4604
authors.initials: P
authors.lastname: Abadi
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Søndre Boulevard 29, 5000, Odense C, Denmark.
authors.forename: Allan
authors.initials: A
authors.lastname: Johansen
authors.affiliation: Department of ENT Head and Neck Surgery, Odense University Hospital, Søndre Boulevard 29, 5000, Odense C, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Godballe
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Søndre Boulevard 29, 5000, Odense C, Denmark.|Centre of Health Economics Research, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
authors.forename: Oke
authors.initials: O
authors.lastname: Gerke
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Søndre Boulevard 29, 5000, Odense C, Denmark.
authors.forename: Poul Flemming
authors.initials: PF
authors.lastname: Høilund-Carlsen
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Søndre Boulevard 29, 5000, Odense C, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Thomassen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D008210:Lymphocele / Q000000981:diagnostic imaging* / Q000473:pathology; D008223:Lymphoma / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D000072078:Positron Emission Tomography Computed Tomography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Branchial cleft cyst; Cervical metastasis; FDG PET/CT; Neck cyst; Necrotic lymph node; PET/CT in cervical cystic lesions