title: [Usefulness and Limitation of Thyroglobulin Measurement in Fine Needle Aspirates (FNA-Tg) for Diagnosis of Neck Lymph Node Metastasis from Thyroid Carcinoma].
abstract: BACKGROUND
  Preoperative diagnosis of lymph node metastasis from thyroid carcinoma is usually confirmed by using fine needle aspiration cytology (FNAC) when thyroid carcinoma is suspected based on the clinical findings. However, the result of FNAC sometimes leads to a false negative, especially in cases of hypocellular lesions such as metastases with cystic change. Thyroglobulin measurement in fine needle aspirates (FNA-Tg) has been shown to be a useful technique to detect the protein specifically secreted by thyroid follicular cells. Elevated FNA-Tg levels in an extra-thyroidal lesion means that the lesion comprises thyroid-originated tissue, most of which suggests the metastasis from thyroid carcinoma. Thus, FNA-Tg is expected to improve the sensitivity of FNAC for the aforementioned purpose.
  
  
  METHODS
  From 2008 to 2012, 49 extra-thyroidal lesions from 43 patients with thyroid carcinoma were examined using both FNAC and FNA-Tg, followed by surgical resection with a histopathological diagnosis. The results were retrospectively reviewed and analyzed.
  
  
  RESULTS
  Among 49 lesions, 47 were metastatic lymph nodes from thyroid carcinoma (46 papillary carcinoma and one follicular carcinoma), one was a metastatic lymph node from submandibular gland adenocarcinoma, and one was an ectopic thyroid gland. In the 47 cases of thyroid carcinoma, the sensitivity of FNAC was 57.4% (27/47), whereas that of FNA-Tg was 76.6% (36/47). When both methods were combined, the sensitivity increased to 93.6% (44/47). Metastasis from submandibular gland adenocarcinoma was considered to be an example of a false positive from FNAC, whereas an ectopic thyroid gland was an FNA-Tg false positive. Three lesions were negative for both FNAC and FNA-Tg, although metastases were suspected by imaging studies and confirmed by histopathological diagnosis, which were consistent with examples of a false negative from both FNAC and FNA-Tg findings.
  
  
  CONCLUSIONS
  FNAC reflects whether the lesion has malignant cells, whereas FNA-Tg reflects whether the lesion has thyroid-originated tissue that specifically secrets thyroglobulin. Therefore, FNAC and FNA-Tg are considered to be complementary to each other for the preoperative diagnosis of lymph node metastasis from thyroid carcinoma. FNA-Tg was validated to improve the preoperative diagnostic sensitivity especially when combined with FNAC, however, it is attended with the possibility of a false positive or negative finding, which requires caution in interpretation of the findings.
authors.forename: Koji
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Yorihisa
authors.initials: Y
authors.lastname: Imanishi
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tomita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ozawa
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Sato
authors.forename: Yozo
authors.initials: Y
authors.lastname: Inagaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamada
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Ito
authors.forename: Noriomi
authors.initials: N
authors.lastname: Suzuki
authors.forename: Takeyuki
authors.initials: T
authors.lastname: Kono
authors.forename: Shin
authors.initials: S
authors.lastname: Saito
authors.forename: Masaru
authors.initials: M
authors.lastname: Noguchi
authors.forename: Takanori
authors.initials: T
authors.lastname: Nishiyama
authors.forename: Shintaro
authors.initials: S
authors.lastname: Nakamura
authors.forename: Hiroko
authors.initials: H
authors.lastname: Fujita
authors.forename: Takahisa
authors.initials: T
authors.lastname: Watabe
authors.forename: Seiichi
authors.initials: S
authors.lastname: Shinden
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ogawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000473:pathology*; D013954:Thyroglobulin / Q000032:analysis*; D013964:Thyroid Neoplasms / Q000737:chemistry / Q000473:pathology*; D055815:Young Adult
chemical_list: D013954:Thyroglobulin