An intrapericardial ectopic thyroid mimicking metastasis in a patient with papillary thyroid cancer: Localization, differential diagnosis by 18F-FDG PET/CT and ablation by 131I

Hell J Nucl Med. 2016 Sep-Dec;19(3):272-274. doi: 10.1967/s002449910411. Epub 2016 Nov 8.

Abstract

We report a very rare case of incidental intrapericardial thyroid in a papillary thyroid cancer patient. Post ablation scan revealed iodine-131 (131I) uptake in the mid-chest. Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) was performed and showed a 18F-FDG avid lesion between the right atrium and the ascending aorta, (which was) shown to be an ectopic thyroid and not metastasis. The lesion disappeared on a 6 month follow-up 123I whole body scan while serum thyroglobulin was negative. Although intrapericardial ectopic thyroid is reported to show high iodine uptake, low 18F-FDG avidity of the lesion could be helpful in the exclusion of metastases.

Publication types

  • Case Reports

MeSH terms

  • Carcinoma / diagnostic imaging
  • Carcinoma / secondary
  • Carcinoma, Papillary
  • Choristoma / diagnostic imaging*
  • Choristoma / radiotherapy*
  • Diagnosis, Differential
  • False Positive Reactions
  • Female
  • Fluorodeoxyglucose F18*
  • Heart Diseases / diagnostic imaging*
  • Heart Diseases / radiotherapy*
  • Heart Neoplasms / diagnostic imaging
  • Heart Neoplasms / secondary
  • Humans
  • Iodine Radioisotopes / therapeutic use
  • Middle Aged
  • Positron Emission Tomography Computed Tomography / methods
  • Radiopharmaceuticals / therapeutic use
  • Thyroid Cancer, Papillary
  • Thyroid Gland / diagnostic imaging*
  • Thyroid Neoplasms / diagnostic imaging
  • Thyroid Neoplasms / secondary

Substances

  • Iodine Radioisotopes
  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18