Differential diagnosis of follicular thyroid tumors using core-needle biopsy

Background. In recent decades, there has been an increase in the incidence of malignant neoplasms of the thyroid gland by 20%. In 2020, thyroid cancer was diagnosed in 586,202 people worldwide and caused 43,646 deaths. Diagnosis of thyroid carcinoma has stepped forward due to the introduction of fine needle aspiration biopsy into widespread practice, with the classification of cytological material according to the Bethesda system. However, one category of this classification traditionally remains a gray area of diagnosis. The detection of a follicular tumor in the cytological material (category IV according to Bethesda) does not allow one to reliably classify the formation as benign or malignant and requires surgical intervention. At the same time, in the vast majority of cases, the tumor is benign.Aim. To evaluate the possibilities of trephine biopsy for the differential diagnosis of benign and malignant neoplasms of the thyroid gland in the cytological category Bethesda IV.Materials and methods. The study included 8 patients (2 men and 6 women) with a nodular thyroid gland and a cytological picture of a follicular tumor (Bethesda IV). The age of the patients ranged from 21 to 67 years, mean age 52.12±16.12. The sizes of nodule at US in three projections were accordingly 11,66±1,52; 11.33±1.15; 10.66±1.52 mm. Before the intervention, patients canceled drugs that affect the blood coagulation system. All patients underwent a trephine biopsy under ultrasound guidance with a mandatory assessment of blood supply in the mode of color Doppler mapping and power Dopplerography. Manipulation was performed along the midline of the neck through the isthmus of the thyroid gland. The material was taken from at least two sites, one through the tumor tissue, the other along the edge of the tumor with the capture of the capsule with a 18G needle. Additional biopsies were performed if a tumor site suspicious of malignancy was identified.Results. The results of trephine biopsy coincided in 8 cases (100%) with the results of an urgent and planned histological examination. The obtained data were regarded as highly informative in 5 cases (62.5%) and medium informative in 3 cases (37.5%). The material reliably assessed the morphological type of the tumor, the degree of vascularization of the capsule, the presence or absence of invasion into the capsule or vessels. Histological studies made it possible to assess the size of the follicles, the presence of colloid, cell polymorphism, mitoses, and the contents of the cytoplasm; evaluate cell atypia.Conclusion. In the future, trephine biopsy may become an additional opportunity to identify tumor-like formations in patients with follicular thyroid tumors.