Positron emission tomography (PET) positive thyroid incidentaloma: the risk of malignancy observed in a tertiary referral center.

An incidental finding of focal thyroid uptake (thyroid incidentaloma) from an 18F-fluorodeoxyglucose positron emission tomography (PET) positron presents a diagnostic challenge. We evaluated the incidence of thyroid incidentaloma identified by PET scans and the likelihood of malignancy associated with this finding. Records from all patients from January 1, 2000 to November 30, 2003 who had focal thyroid uptake without any history of thyroid disease were culled. Of the 6241 PET scans performed, focal thyroid uptake was observed in 76 patients (1.2%). Only 14 patients (18%) underwent biopsy. Four of 14 patients (28.6%) had papillary thyroid carcinoma, 7 (50%) had hyperplasia, and 1 each had thyroiditis, nodular goiter, and follicular neoplasm. The incidence of PET thyroid incidentalomas was 1.2 per cent and the incidence of malignancy was 28.6 per cent. Given the high likelihood of malignancy, a further diagnostic workup for surgically fit patients is warranted.