title: Frontal sinus mucocele mimicking a metastasis of papillary thyroid carcinoma.
abstract: Radioiodine scans are highly specific for detecting metastases of well-differentiated thyroid carcinomas. However, false-positive 131I whole-body scans may occur as illustrated in the following case report. In a 53-yr-old patient, abnormal 131I uptake was found in the right frontal skull 4 wk after total thyroidectomy and radioiodine therapy for papillary thyroid cancer. Bone scans and planar x-rays of the skull were unremarkable and the serum thyroglobulin level was within normal limits. X-ray CT revealed a small nodule in the right frontal sinus corresponding to the pathological focus of 131I uptake. Surgical removal and histopathological examination of this lesion yielded a mucocele, a slow-growing lesion of the paranasal sinuses accumulating mucous material. The postoperative 131I scan was unremarkable. The possibility of a false-positive finding on radioiodine scans should be considered, particularly when the serum thyroglobulin level is not elevated.
authors.affiliation: Clinic of Nuclear Medicine, University Hospital of Westfälische Wilhelms-University of Münster, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Matheja
authors.forename: H
authors.initials: H
authors.lastname: Lerch
authors.forename: K W
authors.initials: KW
authors.lastname: Schmid
authors.forename: T
authors.initials: T
authors.lastname: Kuwert
authors.forename: O
authors.initials: O
authors.lastname: Schober
mesh_terms: D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000556:secondary*; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D005626:Frontal Sinus / Q000000981:diagnostic imaging*; D006801:Humans; D007457:Iodine Radioisotopes; D008875:Middle Aged; D009078:Mucocele / Q000000981:diagnostic imaging*; D010254:Paranasal Sinus Diseases / Q000000981:diagnostic imaging; D010255:Paranasal Sinus Neoplasms / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D013964:Thyroid Neoplasms / Q000473:pathology*; D014057:Tomography, X-Ray Computed
chemical_list: D007457:Iodine Radioisotopes