Surgery 2001 Dec;130(6):941-6
Risk of malignancy in thyroid incidentalomas identified by fluorodeoxyglucose-positron
emission tomography.
Cohen MS, Arslan N, Dehdashti F, Doherty GM, Lairmore TC, Brunt LM, Moley JF.
BACKGROUND: Thyroid tumors often exhibit increased metabolic activity, as
evidenced by enhanced glucose uptake on positron emission tomography (PET) with
use of (18)F-fluorodeoxyglucose (FDG). The incidence of new thyroid lesions
found on routine FDG-PET has not been previously reported. METHODS: A
retrospective review of all patients who underwent FDG-PET imaging at our
institution from June 1, 1996, through March 15, 2001, identified patients with
a newly diagnosed thyroid lesion. Thyroid incidentaloma was defined as a thyroid
lesion seen initially on FDG-PET in a patient without a history of thyroid
disease. Available follow-up data were documented. RESULTS: One hundred and two
of 4525 FDG-PET examinations (2.3%) demonstrated thyroid incidentalomas.
Eighty-seven of 102 patients had no thyroid histology because of other
malignancies. Fifteen patients had thyroid biopsy: 7 (47%) with thyroid cancer,
6 (40%) with nodular hyperplasia, 1 with thyroiditis, and 1 with atypical cells
of indeterminate origin. The average standardized uptake values were higher for
malignant compared with benign lesions. CONCLUSIONS: Thyroid incidentaloma
identified by FDG-PET occurred with a frequency of 2.3%. Of the thyroid
incidentalomas that underwent biopsy, 47% were found to be malignant. Given the
risk of malignancy, patients with new thyroid lesions on PET scan should have a
tissue diagnosis if it will influence outcome and management. Standardized
uptake values may be helpful in predicting benign versus malignant histology.
