Metastatic thyroid cancer occurring as an unknown primary lesion: the role of F-18 FDG positron emission tomography

Clin Nucl Med. 2001 May;26(5):396-9. doi: 10.1097/00003072-200105000-00004.


Thyroid cancer can appear as metastatic disease of an unknown primary origin, and fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomographic (PET) studies are helpful in the workup evaluation of these patients. The authors describe two patients who had metastatic disease from an unknown primary lesion. F-18 FDG PET studies played an important role in localizing the primary malignant site in the thyroid gland. The utility of F-18 FDG imaging in decreasing the number of procedures, cost, and inconvenience to patients is shown clearly in both cases.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Bone Neoplasms / diagnostic imaging
  • Bone Neoplasms / secondary
  • Female
  • Fluorodeoxyglucose F18*
  • Humans
  • Lung Neoplasms / diagnostic imaging
  • Lung Neoplasms / secondary
  • Male
  • Middle Aged
  • Neoplasms, Unknown Primary / diagnostic imaging*
  • Radiopharmaceuticals*
  • Thyroid Neoplasms / diagnostic imaging*
  • Thyroid Neoplasms / pathology
  • Tomography, Emission-Computed*
  • Whole-Body Counting


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18