N. Swaminathan1, A.J. Laboy1, R. Akhund1, A. Allahwasaya1, S. Balachandra1, C. Mcleod1, A. Gillis1, J. Fazendin1, B. Lindeman1, H. Chen1 1University Of Alabama at Birmingham, Endrocrine/ Surgery/University Of Alabama At Birmingham, Birmingham, Alabama, USA
Intro: The incidence of thyroid nodules measuring ≥4 centimeters (cm) has increased over the last decade, especially in females. These large nodules are particularly concerning for malignancy leading to the common practice of thyroidectomy instead of relying on fine needle aspiration. However, there is a lack of robust evidence on the rate of malignancy in nodules >4 cm. There is always a concern for missing a hidden malignancy that can be missed by biopsies. This study aims to determine the rate of “hidden” neoplasms in thyroid nodules ≥4 cm.
Methods: We retrospectively analyzed patients who underwent partial or total thyroidectomy from 2015–2024 at a large tertiary care center. Data collected included patient demographics, Body Mass Index (BMI), thyroid nodule size, and final surgical pathology to determine the malignancy rate. Patients with nodules ≥4 cm were divided into two groups depending on their pathology: benign or malignant.
Results: A total of 1049 patients were analyzed with 167 (16 %) having nodules ≥4 cm, out of which 23% (n=38) were malignant.
The average age of patients with thyroid malignancy was 49 years (SD+/- 18). Female (75%, n=124) and white (54%, n=90) patients accounted for majority of the ≥4 cm group. Among the malignant neoplasms, 34% (n=13) were found incidentally “hidden” in a larger benign nodule. The average size of the incidental neoplasm was 1.81 cm (SD +/- 1.67). Females and white patients also accounted for the majority of the malignant group (68%, n=26, and 61%, n=23, respectively). The rest (n=129, 77%) of the ≥4 cm nodules were benign, out of which 20% (n=26) were neoplastic follicular lesions (adenomas or nodular). A majority (57%, n=95) of nodules ≥4 cm underwent Fine Needle Aspiration (FNA) prior to thyroidectomy. Of these, only 66% (n=63) of the FNA findings matched their final pathology report. Of the 13 malignant neoplasms incidentally found hidden in a larger benign nodule, 6 had an FNA performed with only 2 accurately discovering a hidden neoplasm.
Conclusion: Thyroid nodules ≥4 cm have a significant chance to harbor neoplasia, with some hidden inside of biopsied benign nodules. Nearly 1/3 of nodules were neoplastic requiring removal because of concern for current or future malignancy. Based on these findings, surgical resection should be considered for every thyroid nodule ≥4 cm.