CORE NEEDLE BIOPSY VERSUS FINE NEEDLE ASPIRATION IN THE DIAGNOSIS OF ANAPLASTIC THYROID CANCER: WHICH IS THE BEST?

Background Anaplastic thyroid cancer (ATC) is a rare but extremely aggressive cancer of the thyroid. Preoperative identification of ATC is extremely important to better plan patient management and to avoid useless and potentially dangerous surgical procedures. High-grade histological features (necrosis and mitoses) and cellularity for a definitive diagnosis of ATC can be difficultly recognized in the fine-needle aspiration (FNA) sample. Core needle biopsy (CNB) is already used as an alternative to FNA and mainly to surgical biopsy for preoperative diagnosis of other tumors. The study aims to compare the diagnostic efficacy of CNB vs. FNA in a large series of locally advanced neck cancers suspicious for ATC from a single center. Patients and Methods: between April 2014 and November 2019, 85 cases of locally advanced neck cancers suspicious for ATC were collected. All cases simultaneously underwent FNA and CNB. Thyroglobulin, TTF-1, and other immunohistochemical cytokeratins were analyzed in all CNB samples. The epidemiological, clinical, and pathological data were collected. Results: 96.5% (82\85) of CNB samples were diagnostic (32\85, 37.6% for ATC; 28\85, 33% for poorly differentiated thyroid cancer (PDTC) ; 22\85, 25,9% for lymphoma or metastases from other primary tumors). No major complications were reported. In the FNA series, the cytological diagnosis was ATC in 5\85 (5.9%), PDTC in 34\85 (40%), thyroid cancer (Tir 5) in 19\85 (22,3%) and insufficient for a diagnosis (Tir 1) in 22\85 (25,9%). Only 22\85 (25.9%) patients underwent surgical procedure, 63\85 (74.1%) patients were excluded by surgery because of a preoperative evidence of cervical bundle, oesophageal and tracheal massive infiltration. In 21\22 (95,4%) cases, preoperative CNB diagnosis was confirmed by the final histological examination, while FNAC was positive for ATC only in 8\22 (36.3%) Conclusions: CNB resulted in being a safe and effective procedure to preoperatively diagnose ATC and to plan the most appropriate treatment for the patient avoiding surgical biopsy.