Endocrine Abstracts

Introduction: Thyroid nodules are discovered by ultrasound (US) in a large percentage of population. In most cases they are benign and asymptomatic. When to perform or not a fine-needle-aspiration (FNA) is still matter of debate. Aim of this study was to evaluate the usefulness of a easy-to-use US classification, based on three US classes.

Methods: We prospectively evaluated US features of 1118 thyroid nodules, allocating each nodule in one of three classes, depending on the number of US findings of malignancy: US1 (0-1 finding), US2 (2 findings), US3 (3 or more findings). US evaluation was made using traditional B-Mode and Power-Doppler high-frequency US. We considered the following five US features as finding of malignancy: hypoechogenicity, micro(macro)calcifications, irregular margins, taller-than-wide shape, and intranodular chaotic vascularisation. All nodules were then submitted to FNA, and cytological results were compared to US classification.

Results: Excluding 106 nodules with non diagnostic cytology (Thy1) and 3 nodules with non-thyroidal cytological diagnosis (parathyroid gland or epidermoid cyst), in the remaining 1009 nodules FNA provided the following results:

US1: Thy2=563, Thy3=39, Thy4=2, Thy5=0

US2: Thy2=182, Thy3=90, Thy4=6, Thy5=3

US3: Thy2=27, Thy3=47, Thy4=20, Thy5=30

The distribution of FNA results showed a significant correlation (r=0.597) with US classification. Considering thyroid nodules with indeterminate cytology (Thy3), 111 nodules were submitted to thyroidectomy. In this subgroup of patients, the histological result (benign or malignant) showed a significant difference among the three US classes, according to US stratification of suspicion.

Conclusion: Our data confirm the accuracy of traditional US findings in the first diagnostic evaluation of thyroid nodules, proposing a simple, easy-to-use US classification of thyroid nodules. Together with clinical features, this classification might be useful when we have to decide if performing or not a FNA.