Correlation of thyroid nodule fine-needle aspiration cytology with corresponding histology at Mayo Clinic, 2001-2007: an institutional experience of 1,945 cases

Following the National Cancer Institute Thyroid Fine Needle Aspiration State of the Science Conference, the thyroid fine-needle aspiration biopsy (FNAB) practice at Mayo Clinic, Rochester, Minnesota, conducted retrospective analyses correlating cytologic and histologic evaluations of thyroid nodules. Cytologic and histologic reports were retrieved for patients with thyroid nodules who underwent thyroid FNAB between January 2001 and December 2007, with subsequent surgical thyroid resection. Cases were classified by major cytologic and histologic diagnosis and specific diagnostic subcategories. Of 1,945 FNAB cytologic results, 180 (9.3%) were nondiagnostic; 512 (26.3%) were negative for malignancy; 27 (1.4%) were atypical; 729 (37.5%) were suspicious for malignancy; and 497 (25.6%) were positive for malignancy. Histology was benign in 1,179 (60.6%) and malignant in 766 (39.4%). For thyroid malignancy as the disease outcome, at cytologic thresholds of atypical, suspicious, and positive, overall sensitivity of thyroid FNAB was 94.5%, 94.1%, and 65.0%, respectively, and specificity was 46.0%, 48.3%, and 98.5%, respectively. Positive predictive value for all malignancies was 97.0%, and negative predictive value was 92.0%. When separated by specific malignant outcomes, diagnoses of papillary carcinoma, medullary carcinoma, and lymphoma had specificity of suspicious FNAB diagnoses ranging from 90.5% to 99.6%; positive predictive value ranged from 87.5% to 91.4%. For follicular or Hurthle carcinoma, suspicious FNAB diagnoses had a specificity of 52.5% and a positive predictive value of 5.9%. Sensitivity of indeterminate FNAB diagnoses ranged from 72.7% to 95.3%. For follicular or Hurthle pattern malignancies, indeterminate cytologic diagnoses should be interpreted with caution by the clinician considering surgical management. Diagn. Cytopathol. 2012;40:E27-E32. © 2010 Wiley Periodicals, Inc.