Endocrine Abstracts

Introduction: Ultrasound (US) thyroid examination is the most common method to assess thyroid nodules risk of malignancy and select nodules for fine-needle aspiration biopsy (FNAB). Thyroid US evaluation performed by endocrinologists has recently increased in Spain.

Objectives: To evaluate the predictive value of US features of malignancy in differentiating benign and malignant thyroid lesions in a Thyroid Nodule Clinic.

Patients and methods: Retrospective analysis of 296 patients referred to an Endocrinology Department for US thyroid nodule evaluation, between October 2016 and October 2017. US features assessed in each nodule were: size, hypoechogenicity (HE), shape taller than wide (T>W), irregular margins (IM), intranodular vascularity (IV) and microcalcification (MC). A total of 337 nodules were selected for FNAB and were classified based on the Bethesda system. Thirty-three cases with Bethesda categories different from benign without histological diagnosis, were excluded for accuracy study. The sensivity (Se), specifity, negative (NPV) and positive (PPV) predictive value and accuracy of US features were evaluated.

Results: A total of 296 patients (250 women), median age 55 years old were included. TSH median was 1.6 mcUI/ml, 31% with positive thyroid antibodies. The median nodule size was 1.8 cm. In 119 nodules (35%) there were no sonographic malignancy features. In these cases, the US assessment of malignancy had a NPV of 99%. In 218 nodules (65%) there was one or more US malignancy feature: HE (42%), T>W (5.6%), IM (15.7%), IV (22%) and MC (12%). Hypoechogenicity had the highest Se (56%) but its PPV was low (7%). Microcalcification had the highest PPV (19.4%) for malignancy diagnosis with a Se 37.5%.

Conclusion: Nodules with at least one US malignancy feature, specially microcalcification, should undergo FNAB. In nodules without any US malignancy feature, histological malignancy diagnosis is highly improbable.