Triple-tracer Functional Imaging in a Rare Case of Thyroid Paraganglioma

Abstract

A 79-year-old woman with suspected choroidal lesion underwent 18F-FDG PET/CT, which revealed a non-FDG-avid right thyroid lobe incidentaloma (4.8 cm in largest dimension) that was cold on 99mTc-thyroid scan, showed intense SSTR expression on 68Ga-DOTATATE PET/CT, and MIBG avidity on 131I-MIBG scan, thereby proving it to be of neural crest origin. Fine needle aspiration biopsy (FNAB) with immunohistochemistry was positive for GATA3 and synaptophysin and negative for CK7, PAX8, TTF1, and calcitonin, establishing the diagnosis of thyroid paraganglioma. Even though rare, the diagnosis of paraganglioma should be considered in SSTR and MIBG-avid thyroid nodules, as seen in this case.

Keywords: thyroid paraganglioma.