Malignancy rates and risk factors in Bethesda category IV thyroid nodules: Is lobectomy enough in an endemic region?

In this paper, we determined the rates of Bethesda IV thyroid nodules and calculated the malignancy rates of these nodules in a university hospital located in an endemic area for thyroid diseases. We aimed to define the predictive factors for malignancy to select patients who need surgery. We included in the study 221 patients who had a preoperative biopsy for follicular neoplasm or because of suspicion for follicular neoplasm and underwent thyroidectomy between January 2012 and December 2018. We evaluated the data about patient characteristics, preoperative ultrasound results, indications for operation and postoperative pathological valuation results and calculated ratio of Bethesda Category IV nodules and incidental malignancy rates. The malignancy rate of Bethesda Category IV nodules was 48.9 %, while the incidental malignancy rate was 30.7 %. There was no statistical difference between patients with benign and malignant pathology results in terms of gender, age, preoperative diagnosis, size of the index nodule, number and results of biopsies and the thyroidectomy performed. The most important risk factor among all parameters was hypoechogenicity of the nodule. The solid structure increases this risk. Ultrasonographic hypoechogenicity is the most important risk factor for preoperative malignancy risk assessment for Bethesda Category IV thyroid nodules. Centers should determine their malignancy rates with particular risk factors and surgical approaches in endemic regions.