On-site fine-needle aspiration cytology of thyroid nodules. Quality assurance of the Bethesda System for Reporting Thyroid Cytopathology (2008)

Background: The methods available for the diagnosis of thyroid nodules include physical examination, imaging, laboratory and fine-needle aspiration cytology tests.

Objective: The aim of this study was to determine the quality assurance of fine-needle aspiration cytology of thyroid nodules.

Methods: Cytology results were rated to 6 categories according to the Bethesda System for Reporting Thyroid Cytopathology (2008) (I. nondiagnostic; II. benign; III. atypia of undetermined significance; IV. follicular neoplasia; V. suspicious for malignancy; VI. malignant). All cytology reports were compared with the final histology diagnosis.

Results: A total of 1384 patient with thyroid nodule underwent fine-needle aspiration biopsy cytology. Smears were classified I. inadequate in 214 (15.9%); II. benign 986; III. atypical 56; IV. follicular neoplasm 41; V. suspicious for malignancy 18; VI. malignant 33 cases. Two hundred and twenty seven (16.8%) of the cases were operated and histologically verified. The positive predictive value in the benign category was 98.25% and in the malignant 88.46%. The sensitivity of the follicular neoplasm was 66.67%.

Conclusions: The results suggest that fine-needle aspiration cytology of thyroid nodules using the Bethesda System for Reporting Thyroid Cytopathology has a high diagnostic accuracy. The auditing values of the results meet the proposed threshold values.