title: Uptake of I-131 by an abdominal neurilemoma mimicking metastatic thyroid carcinoma.
abstract: I-131 whole-body imaging may show characteristic findings in functioning, metastatic differentiated thyroid carcinoma. Nonthyroidal tumor uptake of I-131 is rare, but may mislead the physician to inappropriate treatment. A case is reported of a 59-year-old woman with papillary thyroid carcinoma who demonstrated strong uptake of I-131 in an abdominal cystic neurilemoma. Her serum thyroglobulin concentration at that time was low, at 3.35 ng/ml. Although the concentrating mechanism of I-131 was not clear, several clues pointed to the possibilities of nonthyroidal tumor uptake: 1) faster clearing of radioactivity than usual thyroid tissue, 2) persistent low serum thyroglobulin concentration, and 3) the presence of a cystic component in the nonthyroidal tumor.
authors.affiliation: Department of Nuclear Medicine, Chang Gung Memorial Hospital, Chang Gung Medical College, Kaohsiung, Taiwan, Republic of China.
authors.forename: P W
authors.initials: PW
authors.lastname: Wang
authors.forename: H Y
authors.initials: HY
authors.lastname: Chen
authors.forename: C H
authors.initials: CH
authors.lastname: Li
authors.forename: W J
authors.initials: WJ
authors.lastname: Chen
mesh_terms: D000008:Abdominal Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000556:secondary*; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000000981:diagnostic imaging*; D009442:Neurilemmoma / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D013669:Technetium Tc 99m Medronate; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000473:pathology*
chemical_list: D007457:Iodine Radioisotopes; D013954:Thyroglobulin; D013669:Technetium Tc 99m Medronate