title: Thymic uptake after high-dose I-131 treatment in patients with differentiated thyroid carcinoma: a brief review of possible causes and management.
abstract: OBJECTIVE
  To report five cases of patients diagnosed with differentiated thyroid carcinoma (DTC) with uptake in the thymic area after high-dose treatment with I-131 and to evaluate the potential causes and therapeutic management.
  
  
  METHODS
  Five cases of young female patients with a mean age of 36.6 years (24-43) who had been treated with a mean dose of 106 mCi of I-131 (100-150 mCi) showing tracer uptake in the thymic area are reported. An I-131 whole-body scan (131I-WBS) was performed 7 days after therapeutic dose administration to each patient. Anterior and posterior planar images, followed by SPECT/CT of the head, neck and superior mediastinum were acquired in all patients. Thyroglobulin levels were measured with and without hormone replacement therapy in all cases. Samples taken from the superior mediastinum were sent to pathology for analysis, which confirmed the presence of thymic tissue.
  
  
  RESULTS
  Two patients underwent elective total thymectomy due to the gross characteristics of the gland, local 131-I uptake, and high thyroglobulin levels. The remaining three patients had already undergone thymectomy as part of neck dissection during initial surgery, and no further invasive interventions were therefore performed. Pathological examination revealed no metastases in these five patients.
  
  
  CONCLUSIONS
  Thymus visualization in young patients after administration of therapeutic doses of I-131 seems to be a more common finding than usually thought. Absence of metastasis in the thymus despite high thyroglobulin levels was confirmed in all cases. Based on these results, we suggest that a more expectant and less aggressive therapeutic approach could be used. We also suggest that I-131 therapy for DTC should be considered in classification of the potential causes of true thymic hyperplasia in the subgroup of patients recovering from a stressor.
authors.affiliation: Department of Nuclear Medicine, Hospital Universitario Virgen Macarena, Seville, Spain. Electronic address: m_borbon@hotmail.com.
authors.forename: Manrique Borbón
authors.initials: MB
authors.lastname: Arce
authors.affiliation: Department of Nuclear Medicine, Hospital Universitario Virgen Macarena, Seville, Spain.
authors.forename: Teresa Cambil
authors.initials: TC
authors.lastname: Molina
authors.affiliation: Department of Nuclear Medicine, Hospital Universitario Virgen Macarena, Seville, Spain.
authors.forename: Tomás Martín
authors.initials: TM
authors.lastname: Hernández
authors.affiliation: Department of Nuclear Medicine, Hospital Universitario Virgen Macarena, Seville, Spain.
authors.forename: María
authors.initials: M
authors.lastname: de la Cinta Calvo Morón
authors.affiliation: Department of Nuclear Medicine, Hospital Universitario Virgen Macarena, Seville, Spain.
authors.forename: Cristina Hernández
authors.initials: CH
authors.lastname: Herrero
authors.affiliation: Department of Nuclear Medicine, Hospital Universitario Virgen Macarena, Seville, Spain.
authors.forename: Pablo Antonio
authors.initials: PA
authors.lastname: De La Riva Pérez
authors.affiliation: Department of Nuclear Medicine, Hospital Universitario Virgen Macarena, Seville, Spain.
authors.forename: Juan Castro
authors.initials: JC
authors.lastname: Montaño
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000175:diagnosis / Q000532:radiotherapy* / Q000601:surgery; D000328:Adult; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008207:Lymphatic Metastasis; D037981:Neck Dissection; D019275:Radiopharmaceuticals / Q000627:therapeutic use*; D013934:Thymectomy; D013950:Thymus Gland / Q000000981:diagnostic imaging* / Q000473:pathology; D013952:Thymus Hyperplasia / Q000000981:diagnostic imaging* / Q000209:etiology / Q000601:surgery; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000532:radiotherapy* / Q000601:surgery; D015899:Tomography, Emission-Computed, Single-Photon; D051598:Whole Body Imaging; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D013954:Thyroglobulin
keywords: Captación; I-131; Rastreo de cuerpo completo; Thymus; Timo; Uptake; Whole body scan