Active Surveillance of Indeterminate Thyroid Nodules: Beyond Cytological Diagnosis, Ultrasound Evaluation and Molecular Analysis: Outcome of Indeterminate Thyroid Nodules

Abstract

Background: Approximately 25% of nodules are classified as indeterminate after Fine-Needle Aspiration Biopsy (FNAB). Strategies for stratifying nodules according to risk are now needed in order to reduce unnecessary thyroid surgery. The aim of the study was to report the results of active surveillance in Thy 3 nodules, according to the British Thyroid Association, in which thyroidectomy was refused or postponed.
Methods: Eighty-seven nodules with indeterminate thyroid cytology underwent active surveillance. Active surveillance includes: calcitonin and thyroid blood tests, neck Ultrasonography (US), Elastosonography (USE), Contrast-Enhanced US (CEUS), mutation analysis and a 2nd FNAB. A 36-month period of active surveillance is scheduled.
Results: The 2nd FNAB resulted in down-classification to Thy 2, confirmation of Thy 3 category and subclasses with changes in Thy 3 subclasses (6%) - and non-diagnostic information in 51%, 30% and 13% of cases, respectively. No upgrade of Thy category was observed when a further FNAB was performed during the observation period. US score and maximal nodule diameter did not change significantly from the baseline to the last examination. When surgery was performed during the observation period, malignancy was found in 17% of nodules. US score and CEUS indexes were significantly related to thyroperoxidase antibody positivity and US score, respectively.
Conclusions: Our prospective study suggests that active surveillance can be proposed for patients with indeterminate cytology and no other risk factors. Down-classification to Thy 2 is frequent when further information and material are collected for the pathologist. Simple changes in nodule diameter do not warrant surgery. However, more data are needed.