NOT ALL BETHESDA 1 THYROID NODULES WERE CREATED EQUAL: DIFFERENT B1 SUBGROUPS

Abstract Objective The Bethesda System for Reporting Thyroid Cytopathology is a uniform method used worldwide to report thyroid fine needle aspiration (FNA) outcomes. This study focuses on the Nondiagnostic/Unsatisfactory category, designated as Bethesda1 (B1). The documented risk of malignancy for B1 nodules can vary significantly, implying this category is not homogenous and might be composed of different subtypes. Our hypothesis was that B1 subgroups (blood only, insufficient thyrocytes, cyst content) will vary in their malignancy rate. Methods The study design was observational and retrospective. The study population included 154 patients in the Galilee Medical Center, who underwent FNA examination of the thyroid gland between 2013-2018, with a B1 result. We looked at the final diagnosis of malignant or benign for patients who underwent surgery and calculated the malignancy rate for each subgroup. Results Malignancy rates were higher in the Blood subgroup than in other subgroups, and higher in the Thyrocytes subgroup than in the Cyst subgroup (p Conclusions The different malignancy rates suggest that individual management approaches should be considered for each B1 subgroup.