Ultrasound-Guided Fine-needle Aspiration of the Thyroid in Cytology Practice - Abstract
Background: Fine-needle aspiration (FNA) of the thyroid gland is a widely accepted and accurate method for triaging patients with thyroid nodules. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is used to standardize terminology and convey the risk of malignancy.
Objective: The aim of the study is to analyze the benefit of ultrasound in our daily cytology practice and the utility of the TBSRTC to predict the malignancy risk. We correlated cytology and ultrasound findings with histology reports.
Methods: Data on patient cytology were retrieved by a retrospective search of all thyroid fine needle aspiration cytology (FNAC) reports issued at the Department of Cytopathology, Söder Hospital, Karolinska University from January 2012 to June 2013. A total of 619 specimens were reclassified according to the TBSRTC. When applicable the cytological diagnosis was compared with follow-up cytology and/or
the histology report.
Results: Cytology results were nondiagnostic in 24 (3.87%) nodules, benign in 553 (89,33%), atypia of undetermined significance or follicular lesion of undetermined significance,6 (1 %), follicular neoplasm or suspicious for a follicular neoplasm 14 (2.26 %), suspicious for malignancy,5 (0.8%), and malignant in 17 cases (2,7 % of the lesions).FNA showed a sensitivity of 84.62%, a specificity of 99.33 %, with prevalence
of a malignant disease in 4.15 %.Ultrasonography proved to be very useful in our daily cytology practice in order to achieve representative samples. A representative specimen was obtained in 95% of patients examined by ultrasound. When ultrasound was not used, only 87 % of the patients presented a representative cell sample. Papillary thyroid cancer accounted for 65% of the cancers, followed by follicular neoplasm (25%), anaplastic carcinoma (5%), and metastatic renal cancer (5%).
Conclusion: Ultrasound is an important diagnostic modality for the evaluation of thyroid lesions, providing crucial information about the nature of the lesion. Its use in cytology practice increases the chance of obtaining an adequate cytological specimen, reaching a correct diagnosis, and avoiding unnecessary surgery. This study also demonstrates that the ultrasound can be handled by the cytologist him/herself,
which has obvious practical advantages.