False-positive ¹³¹I Uptake in a Carotid Body Tumor Mimicking Nodal Metastasis in Differentiated Thyroid Carcinoma: Implications of Hybrid SPECT/CT.
Srinivas Ananth Kumar, Nandini Pandit, Prashanth Srinivasan et al.
✦ AI-curated · Sources linked
Case in brief
A 50-year-old woman with follicular variant papillary thyroid carcinoma was found to have a carotid body tumor eight years after treatment. The tumor showed mild, unexpected uptake on radioiodine imaging, raising concern for nodal metastasis. Hybrid SPECT/CT localized the uptake to the carotid body tumor, identifying it as a false-positive finding rather than metastatic thyroid cancer.
What made this case unusual
The carotid body tumor demonstrated mild radioiodine uptake, although these tumors typically show avidity on somatostatin receptor-based imaging rather than radioiodine studies.
Diagnostic / clinical pearl
When radioiodine uptake suggests nodal metastasis, correlate functional findings with structural imaging; SPECT/CT can localize nonspecific uptake and clarify its source.
Why it matters
Correctly identifying the uptake source may help prevent misclassification as metastatic disease and unnecessary therapeutic interventions.