title: Increased 18F-FDG uptake mimicking thyroid cancer in a patient with Hashimoto's thyroiditis.
abstract: We report the case of a 68-year-old patient with a known paravertebral malignant schwannoma, sent to us for postoperative staging. A combined whole-body PET/CT scan showed only poor (18)F-fluorodeoxyglucose uptake in the region of the primary tumor but distinct increased fluorodeoxyglucose uptake in the left and right thyroid gland. Thyroid sonography showed two hypoechogenic nodules. Ultrasound-guided fine-needle aspiration biopsy of one nodule showed oxyphil transformed cells, compatible with malignancy. Based on these findings, the patient underwent a subtotal thyroidectomy. Histopathology of the specimen revealed a chronic follicular Hashimoto's thyroiditis. This case demonstrates that Hashimoto's thyroiditis can mimic thyroid cancer in PET but also in sonography and fine-needle aspiration biopsy.
authors.affiliation: Division of Nuclear Medicine, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland. daniel.schmid@dmr.usz.ch
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Schmid
authors.forename: Stefan
authors.initials: S
authors.lastname: Kneifel
authors.forename: Sandro J
authors.initials: SJ
authors.lastname: Stoeckli
authors.forename: Barbara-C
authors.initials: BC
authors.lastname: Padberg
authors.forename: Griff
authors.initials: G
authors.lastname: Merrill
authors.forename: Gerhard W
authors.initials: GW
authors.lastname: Goerres
mesh_terms: D000368:Aged; D003937:Diagnosis, Differential; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D013967:Thyroiditis, Autoimmune / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D014055:Tomography, Emission-Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18