Study of the C228T mutation of the TERT promoter in thyroid aspirative punctures of IV category of the Bethesda classification.

INTRODUCTION

Since the C228T mutation in theTERT promoter (TERTp) has been identified almost exclusively in thyroid malignancies, our objective was to study the usefulness of its determination in thyroid fine needle aspirations (FNA) of the IV category of the Bethesda classification (B.IV).

METHODOLOGY: From the FNAs performed between 1993 and 2015, we selected those with a diagnosis of B.IV or equivalent and subsequent thyroidectomy. A retrospective study of the C228T mutation in TERTp was performed by pyrosequencing in neoplastic cases (adenomas, low risk neoplasms and carcinomas), both from the surgical specimen and from the FNA material if feasible.

RESULTS

79 cases with a diagnosis of B.IV were identified, and mutational study was performed in the 61 cases corresponding to neoplasms, identifying 10 cases with the mutation (12.6% of the series), with a higher presence in Poorly Differentiated Carcinomas (PDC) or with a minor PDC component (45%), in cases with death attributable to thyroid carcinoma (50%) and in patients alive but with persistence of thyroid carcinoma (50%). The mutation was confirmed in 7 of 8 cases with the mutation and satisfactory cytological material. In 4 cases, preoperative knowledge of the mutation could have avoided a two-stage thyroidectomy.

CONCLUSION

The study of the C228T mutation ofTERTp can be useful to detect malignancy and establish the best surgical approach in patients with thyroid FNA with a diagnosis of B.IV.