Focal uptake of (18)F-fluorodeoxyglucose by thyroid in patients with nonthyroidal head and neck cancers

To evaluate the prevalence and significance of focal thyroid lesions identified by (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) in patients with nonthyroidal head and neck cancers (HNC).

Patients with histologically identified HNC who underwent FDG-PET and computed tomography (CT) were reviewed retrospectively. We evaluated the prevalence of patients with focal thyroid FDG uptake and the risk of malignancy and proper management in these patients.

Of 689 HNC patients, 19 (2.8%) had focal thyroid FDG uptake. Of the 12 patients with a histological diagnosis by surgery or needle biopsy, 5 (41.7%) had carcinomas, 4 papillary and 1 follicular, whereas the others had benign thyroid lesions. The maximum standardized uptake value on PET was not sufficient to discriminate between malignant and benign thyroid lesions (8.4 +/- 13.2 vs. 4.2 +/- 4.0; P > 0.4). The identification of incidental thyroid diseases helped guide patient counselling and combined surgery with HNC and thyroidectomy.

Focal thyroid lesions incidentally found on FDG-PET in patents with nonthyroidal HNC have a high probability of malignancy. These lesions deserve further diagnostic examination before HNC treatment to ensure adequate therapy for incidental thyroid cancers.