Endocrine Abstracts

Fine-Needle Aspiration Biopsy (FNAB) is the recommended diagnostic tool for differentiating malignant from benign thyroid nodules and provides indication for surgical decisions. According to the Italian system, thyroid nodules are classified as TIR 1/1C, TIR 2, TIR 3A, TIR3B, TIR4 or TIR5, which correspond to Thy I, Thy II, Thy III, Thy IV, Thy V and Thy VI categories of the Bethesda system. TIR 3 identifies the indeterminate nodules. Surgery is usually recommended for TIR 3B, TIR 4 and TIR 5 nodules. Among papillary thyroid carcinomas (PTC), the classic and follicular (CV-PTC and FV-PTC) are characterized by a good prognosis and require a less aggressive treatment, while the tall cell (TC-PTC) and the solid variants (SV-PTC) and others rarer (columnar, hobnail and diffuse sclerosing variants) have a worse prognosis. In addition, thyroid ultrasound often identifies thyroid nodules <1 cm, which are usually characterized by an indolent behavior and active surveillance may be advised. We aimed at identifying which ultrasound and cytological features enable to recognize, among TIR4-5 nodules, the aggressive variants and, among TIR3B nodules, the malignant ones. To this purpose we retrospectively analyzed the histopathological records of 1117 patients (for a total of 1668 nodules, 650 malignant) who underwent surgery in 2017 and who had previously undergone FNAB and thyroid ultrasound (available for 390 nodules). Of the 566 PTC, 18.7% were TIR3A, 20.7% TIR 3B and 51.6% TIR4-5, while of 50 FTC 42.0% were TIR3A, 42.0% TIR3B and 6.0% TIR4-5. Of the 11 PDTC 54.5% had been diagnosed as TIR 3B. Of the 249 classic variant of PTC, 0.8% had resulted TIR3A, 14.1% TIR3B and 79.9% TIR4-5. Among 49 TC-PTC, none had resulted TIR3A, 2% had been diagnosed as TIR3B and 95.9% as TIR4-5. Of the 219 FV-PTC 42.0% had resulted TIR3A, 39.7% TIR3B and 12.3% TIR4-5. Among 34 SV-PTC, 32.4% had been diagnosed as TIR3A, 41.2% TIR3B and 0.6% TIR4-5. At ultrasound, blurred margins were the only feature associated with malignancy (P=0.034) in TIR3B category. The coexistence of hypoechogenicity and blurred margins in absence of microcalcifications were more common in the TC (7/28) compared to the CV (10/120) of PTC (P=0.021). In conclusion ultrasound helps to identify, among TIR4 and TIR5 nodules, the aggressive variants, and among TIR3B, the malignant ones, and therefore to choose the extent of surgical treatment and, when <1 cm, to confidently advise active surveillance.