Thyroid nodules with Hürthle cells: the malignancy risk in relation to the FNA outcome category

J Endocrinol Invest. 2019 Nov;42(11):1319-1327. doi: 10.1007/s40618-019-01055-0. Epub 2019 May 10.


Purpose: The aim was to find whether the presence of Hürthle cells (HC) in a smear influences the categorization of FNA results or the risk of malignancy (RoM) of particular categories of cytological diagnosis.

Methods: 25,220 FNA performed in a single center in years 2005-2017 were analyzed. Almost all the examined patients were exposed to moderate iodine deficiency for most of their lives. The distribution of FNA outcome categories was compared between two groups: with or without HC (HC and non-HC). The RoM was evaluated on the basis of postoperative histopathological examination (3082 patients).

Results: HC were found in 7.5% of diagnostic FNA. HC nodules were classified into categories II (78.2% vs. 91.9%, p < 0.0000) and VI (0.4% vs. 1.2%, p = 0.0017) less often than non-HC nodules, but more frequently to categories III (14.4% vs. 5.8%, p < 0.0000), IV (11.2% vs. 0.9%, p < 0.0000) and V (1.5% vs. 0.8%, p = 0.0013). There were no significant differences in RoM between HC and non-HC nodules. The RoM in HC and non-HC nodules of particular categories of the Bethesda system was as follows: II: 1.8% vs. 0.8%, III: 9.7% vs. 3.8% when only the last FNA was considered and 10.8% vs. 6.4% when the category III in any performed FNA was considered; IV: 12.7% vs. 10.9%; V: 41.7% vs. 58.2%; and VI: 100% vs. 96.9%.

Conclusions: HC nodules are classified into categories of equivocal cytological outcomes more often than nodules without HC. Nevertheless, the presence of HC in a smear does not significantly affect the RoM of FNA categories.

Keywords: Cancer; FNA; Hürthle cell; Oxyphilic cell; Thyroid.

MeSH terms

  • Adenocarcinoma, Follicular / diagnosis*
  • Adenocarcinoma, Follicular / surgery
  • Biopsy, Fine-Needle / methods*
  • Cytodiagnosis / methods
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Oxyphil Cells / pathology*
  • Prognosis
  • Thyroid Gland / pathology*
  • Thyroid Gland / surgery
  • Thyroid Neoplasms / classification*
  • Thyroid Neoplasms / diagnosis*
  • Thyroid Neoplasms / surgery
  • Thyroid Nodule / diagnosis*
  • Thyroid Nodule / surgery
  • Thyroidectomy