Endocrine Abstracts

Background: Thyroid nodules are one of the most common clinical entities in Endocrinology practice. Fine needle aspiration (FNA) and the 2017 Bethesda System for Reporting Thyroid Cytopathology have been proved to be an effective tool to identify malignancy risk and guide surgical decision-making. However, thyroid nodules classified as Bethesda (BTH) III and IV remain a challenge, considering the varying risk of malignancy (ROM) found in different papers. The aim of this study is to determine the ROM in BTH III and IV nodules, and its possible correlation with several demographic factors.

Material and methods: Single-centre, retrospective study. Between March 2020 and August 2022, 61 patients with a FNA initially categorized as BTH III or IV underwent thyroid surgery (total or hemi-thyroidectomy). Data included demographic characteristics, FNA cytology result, presence of multinodular goitre (MNG) or solitary nodule (SN), type of thyroidectomy and pathologic diagnosis. Our ROM calculations were compared to the median ROM described in the BTH 2017 Statistics. A p-value less than 0.05 was considered statistically significant.

Results: 48 (78.6%) female and 13 (21.12%) male patients were included in the study. Mean age was 57.3+/-14 years. 5 (8.33%) patients had family history of thyroid disease. 58.33% of the patients had been diagnosed with SN and 43.33% with MNG. 39 FNA reports were compatible with BTH III and 22 with IV. Thyroid cancer cases in the BTH IV group were 40.9%. Surprisingly, this value was higher in the BTH III group (53.8%). ROM calculated in our study was significantly higher than the one proposed in the BTH system report (53.8% vs 18%, IC 95% P<.001). There was no significant difference in the ROM for BTH IV. BTH III was significantly correlated with the diagnosis of papillary carcinoma (P< 0,05), but not with the follicular type. No statistical significance was found between ROM and sex, age, family history of thyroid cancer or presence of SN or MNG.

Conclusions: The obtained ROM in Bethesda category III thyroid nodules in this study is significantly higher than the initially suggested by the Bethesda 2017 consensus. It is comparable to other international cohorts previously reported, but in our study thyroid cancer rates were higher in the BTH III group than in the BTH IV one. Ours is one of the first studies describing these data. Our findings suggest that we might be underestimating the potential for malignancy related to Bethesda III thyroid nodules.