[Diagnostic efficiency of sonographic findings of thyroid nodules in the detection of malignancy]

Abstract

Objective: To evaluate the diagnostic efficiency of sonographic findings (nodule size, the presence of microcalcifications and echogenicity) compared with the results of fine-needle aspiration biopsy (FNAB) of thyroid nodules.

Methods: The results of cytology and the ultrasound characteristics of 341 thyroid nodules were analyzed.

Results: A total of 25.5% of the FNAB were inadequate, 65.1% were benign and 7.9% were suspicious or malignant. The percentage of inadequate samples was clearly larger in nodules smaller that 15 mm but that of malignant cytologies was also larger in this group of nodules (11.1 versus 2.8%: p=0.04). The percentage of inadequate samples among nodules smaller than 10 mm was 66.7% and no malignancies were detected. A notable finding was the absence of suspicious or malignant FNAB in hyperechogenic and anechogenic nodules. In contrast, the echogenic feature most frequently associated with malignancy was hypoechogenicity, although echogenicity, as a whole, was not significantly associated with malignancy (p=0.313). Most cases with microcalcifications (6 of 10) were malignant compared with four of the 239 nodules (1.7%) without calcifications (p<0.001). Multivariate logistic regression revealed that the only variable maintaining a significant association with malignancy was the presence of microcalcifications.

Conclusions: Thyroid cytology is an efficient method to evaluate thyroid nodules larger than 10 mm. The presence of nodule microcalcifications is significantly associated with malignancy, while hyperechogenicity and anechogenicity are associated with benign nodules.