title: Measurement of fine-needle aspiration thyroglobulin levels increases the detection of metastatic papillary thyroid carcinoma in cystic neck lesions.
abstract: BACKGROUND
  Patients with previously resected papillary thyroid carcinoma (PTC) are monitored for disease recurrence/metastasis by ultrasound surveillance and fine-needle aspiration (FNA) cytology. However, accurate diagnosis in lesions with cystic degeneration may be difficult due to scant cellularity. In the current study, the authors evaluated thyroglobulin in FNA (Tg-FNA) for detecting metastatic and/or recurrent PTC in patients with cystic neck lesions after thyroidectomy.
  
  
  METHODS
  The pathology records were retrospectively searched for patients with previously resected PTC and subsequent Tg-FNA on a cystic neck mass. Tg-FNA was measured in needle rinses using a Tg assay. The ultrasound findings, Tg-FNA concentrations, and cytological and follow-up histological diagnoses were correlated.
  
  
  RESULTS
  A total of 21 FNA specimens of cystic lesions from 19 patients were identified. Of 7 cases with cytologic and subsequent histologic diagnoses of metastatic PTC, the median Tg-FNA level was 100,982 ng/mL. Of 8 cytologically benign cases, 7 cases had Tg-FNA levels < 0.2 ng/mL, and 1 aberrant case demonstrated elevated Tg-FNA of > 1000 ng/mL. For 6 cytologically equivocal cases, including 3 classified as atypical/suspicious for carcinoma, 2 classified as insufficient/acellular debris, and 1 classified as spindle cell neoplasm, 4 patients demonstrated markedly elevated Tg-FNA levels (> 150 ng/mL) with subsequent surgical confirmation of metastatic PTC, whereas 2 patients had Tg-FNA levels of < 0.2 ng/mL with negative follow-up. Using a cutoff value of 0.2 ng/mL, Tg-FNA demonstrated a sensitivity of 100% and specificity of 87.5%.
  
  
  CONCLUSIONS
  Tg-FNA is a useful ancillary test that improves the detection of cystic PTC metastases. Particularly in cytologically nondiagnostic cases, the measurement of Tg-FNA helps to distinguish benign from malignant cystic lesions.
authors.affiliation: Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, Maryland.
authors.forename: Brittany J
authors.initials: BJ
authors.lastname: Holmes
authors.forename: Lori J
authors.initials: LJ
authors.lastname: Sokoll
authors.forename: Qing Kay
authors.initials: QK
authors.lastname: Li
mesh_terms: D001707:Biopsy, Needle; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology; D002291:Carcinoma, Papillary; D006801:Humans; D009333:Neck / Q000473:pathology*; D009362:Neoplasm Metastasis; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000378:metabolism*; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000473:pathology
chemical_list: D013954:Thyroglobulin
keywords: cystic neck mass; fine-needle aspirate; metastatic papillary thyroid carcinoma; thyroglobulin