Unveiling the true impact of dominant thyroid nodules: are they really the Culprits?

Multinodular goiter (MNG) is a common endocrine disorder, especially in iodine-deficient regions. While fine-needle aspiration biopsy (FNAB) is used widely for preoperative risk stratification, its diagnostic reliability in MNG remains controversial, particularly for non-dominant nodules. We evaluated the relationship between dominant nodule characteristics and the distribution of malignancy in the non-dominant lobes of patients with MNG, who had malignancy confirmed after total thyroidectomy.

This retrospective cohort study included 266 patients with MNG, who underwent total thyroidectomy between September 2020 and December 2024 and were found to have malignancy on final pathology. Preoperative FNAB results were classified using the Bethesda system and postoperative malignancy status was confirmed through final histopathological examination. The patients were divided into ipsilateral and contralateral/bilateral malignancy groups. Statistical analyses included descriptive methods, univariate and multivariate tests, analysis of variance, and receiver operating characteristic (ROC) curve analyses to identify the factors predicting contralateral/bilateral malignancy. A p-value of < 0.05 was considered significant.

Malignancy was detected in 266 of 577 patients who underwent total thyroidectomy (46.1%), representing the malignancy rate within the surgical cohort rather than the overall MNG population. In this malignant surgical subset, the rate of FNAB-pathology discordance was 20.4%, predominantly driven by Bethesda II (benign) cytology. Contralateral or bilateral malignancy was more common in patients with compression symptoms. ROC analyses identified exploratory size cutoff values (34 mm and 30.5 mm) for predicting laterality among cases of malignancy.

Larger dominant nodules were more frequently associated with malignancy in non-dominant nodules; however, this observation should be interpreted as exploratory given the limited discriminatory performance of the ROC analyses. These findings suggest that a thorough preoperative evaluation of all nodules, beyond the dominant one, may be warranted in selected patients with multinodular goiter. Further prospective studies are required to validate these preliminary observations and establish whether they should influence surgical decision-making.