Clinical relevance of thyroid fluorodeoxyglucose-whole body positron emission tomography incidentaloma

J Clin Endocrinol Metab. 2002 Apr;87(4):1517-20. doi: 10.1210/jcem.87.4.8371.


Fluorodeoxyglucose (FDG) whole body positron emission tomography (PET) scan is increasingly used in the diagnostic work-up or follow-up of patients. In these conditions, positive PET scans with unexpected hot spots within the thyroid region could be defined as thyroid FDG-PET incidentaloma (in analogy with unexpected sonographic thyroid nodules). We describe eight consecutive patients referred to the endocrine department because of thyroid "hot spots," incidentally detected by whole body FDG-PET scan (September 1999 to March 2001). Using ultrasound, fine needle aspiration cytology (FNAC), and histology reports, we tried to identify the pathology underlying thyroid FDG-PET incidentaloma. FNAC showed an indication for surgery in all patients. Surgery has been performed in 7 patients. Malignancy was correctly identified in five patients: two medullary thyroid carcinomas, one with lymph node invasion, and three papillary thyroid carcinomas with invasion through the thyroid capsule in two of the PTC cases. In two patients with a positive FDG-PET scan, FNAC pointed to follicular neoplasms, and final histology reports showed follicular adenoma. In the remaining patient, FNAC revealed a follicular lesion, but surgery has not yet been performed. In conclusion, a small series of consecutive thyroid FDG-PET incidentaloma cases is presented and suggests a high rate of clinically relevant malignancies.

Publication types

  • Case Reports

MeSH terms

  • Adenoma / diagnostic imaging
  • Aged
  • Carcinoma, Medullary / diagnostic imaging
  • Carcinoma, Papillary / diagnostic imaging
  • Female
  • Fluorodeoxyglucose F18*
  • Humans
  • Lymph Nodes / diagnostic imaging
  • Male
  • Middle Aged
  • Neoplasm Invasiveness / diagnostic imaging
  • Radiopharmaceuticals*
  • Thyroid Gland / diagnostic imaging*
  • Thyroid Neoplasms / diagnostic imaging*
  • Tomography, Emission-Computed*


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18