Risk of malignancy in thyroid nodules classified as TIR-3A: What therapy?

The aim of the present study was to assess the clinical applicability of the TIR3A category in managing thyroid nodules, to examine the malignancy rates of TIR 3A and TIR 3B nodules, and to suggest management guidelines for these nodules.

Thyroid cytologies performed in patients referred to our Department between January 2014 and August 2016 were classified according to the guidelines published by the SIAPEC. 102 cases were included in this retrospective study and were divided into two groups: 19 TIR3A were included in group A and 83 TIR3B in group B.

In group A, malignancy was diagnosed in 4 (21.1%) cases, papillary thyroid cancer was found in 3 patients and follicular thyroid cancer in 1; one case was classified as microcarcinoma, in two cancer was multicentric and bilateral and in one central node metastases were observed. In Group B malignancy was diagnosed in 48 (57.8%) patients, papillary thyroid cancer was found in 36 patients and follicular cancer in 12; microcarcinoma was observed in 25 cases, 12 were unilateral multicentric and 7 bilateral multicentric; in 3 cases central node metastases were present.

Thyroid nodules with TIR3A cytology have a lower risk of malignancy than TIR3B cases, for which the new SIAPEC classification has proved accurate and effective. Malignancy rates in nodules with TIR3A cytology are higher than expected, although the real and accurate definition of the risk is extremely difficult. The recommendation to perform an accurate follow-up and repeat the fine-needle aspiration still appears the best option. For better management of patients with TIR3A cytology a careful assessment of risk factors and ultrasound characteristics is always needed. Further multicenter studies with longer follow-up are needed to better define the efficacy of this classification, the actual cancer risk, and the best management of these lesions.