Malignancy rates for Bethesda III and IV thyroid nodules: a retrospective study of the correlation between fine-needle aspiration cytology and histopathology.

Creative Commons License

Yaprak B. , Eruyar A.

BMC endocrine disorders, cilt.20, ss.48, 2020 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 20
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1186/s12902-020-0530-9
  • Dergi Adı: BMC endocrine disorders
  • Sayfa Sayıları: ss.48



Background: Fine-needle aspiration cytology (FNAC) has become a well-established modality in the diagnosis,

staging and follow-up of thyroid nodules. FNAC outcomes are routinely classified using the Bethesda System for

Reporting Thyroid Cytopathology (BSRTC), facilitating appropriate clinical management. Bethesda categories III and

IV encompass varying risks of malignancy. This retrospective study established a possible association between these

cytological categories and malignancy rates in patients treated at a single institution.

Methods: Over a 6-year period, 11,627 FNAC procedures were performed on thyroid nodules. Of these, 814

(59.63%) patients were submitted to thyroidectomy. The nodules of 108 patients were classified as Bethesda

category III and 47 patients as Bethesda category IV. Patient data were reviewed to establish a correlation between

the FNAC results and the final histopathological analyses.

Results: The rates of malignancy among patients who underwent surgery were 25% for category III and 27.6% for

category IV, with no significant differences between categories (p = 0.67). The pathological parameters of malignant

nodules, namely tumour type, size, encapsulation, invasion into the thyroid capsule, extrathyroidal extension and

lymphovascular invasion did not significantly differ between the groups (p > 0.05).

Conclusions: This paper provides a more precise correlation of malignancy rates with thyroid nodules classified as

Bethesda categories III and IV, as our findings are comparable to the literature, giving malignancy rates ranging

from 10 to 30% for category III and 25–40% for category IV. Use of the BSRTC is heterogeneous across institutions,

and there is some degree of subjectivity in the distinction between categories III and IV; therefore, it is crucial to

estimate the rates of malignancy at each institution. Molecular assays are of increasing importance in determining

the need for surgical intervention for thyroid lesions. Gene expression assays using FNAC material may demonstrate

a high predictive value for cytologically indeterminate thyroid nodules diagnosed as Bethesda classes III and IV.

Keywords: Fine-needle aspiration cytology, Thyroid nodule, Thyroidectomy, Malignancy rate