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

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.

Multiparameter analysis of AgNOR in thyroid lesions: comparison with PCNA expression.

The aim of the study was to examine numerous features of argyrophilic proteins related to nucleolar organizer regions (AgNORs) in thyroid tumors, relate them to PCNA expression and evaluate which of these features might be useful in the diagnosis of thyroid lesions. Paraffin sections of 100 thyroid tumors were silver-stained and divided into 9 groups: nodular goiter (NG), simple adenoma (SA), microfollicular adenoma (MFA), follicular carcinoma (FC), follicular variant of papillary carcinoma (PC-F), classical variant of papillary carcinoma (PC-C), Hürthle cell adenoma (HA), Hürthle cell carcinoma (HC), and anaplastic carcinoma (AC). The slides were analyzed with the computerized system for image analysis. A weak correlation was found between PCNA expression and AgNOR size. AC differed significantly from all other examined groups in many features of AgNOR dots. Hürthle cell neoplasms were characterized by the presence of a usually single and relatively large dot. With respect to diagnosing follicular lesions, we found that the evaluation of the total area of dots in the nucleus seemed to be the most useful for discrimination: the assumption of 4.9 micro m2, as a cut-off value, allowed a correct classification of 77% of FC cases. Computer-aided morphometric analysis of AgNORs may be useful in the diagnostics of thyroid lesions.