Initially nondiagnostic ulrasound-guided fine-needle aspiration biopsy of thyroid nodules : value and management

Abstract

[한글]

[영문]I.INTRODUCTIONThe management of patients with thyroid fine-needle aspiration biopsy (FNAB) specimens that are nondiagnostic cytologic results still remains problematic. Aims of this study were to investigate the incidence of thyroid cancer among the initially nondiagnostic cases of FNAB and to compare the final cytopathologic results between probably benign and suspicious nodules in ultrasonography (US) with suggesting the management of initially nondiagnostic thyroid nodules at FNABs.II.MATERIALS AND METHODSFrom July 2006 to December 2009, 10,317 thyroid nodules in 6,684 consecutive patients underwent US-guided FNAB. Among them, 871 thyroid nodules (8.4%) that were diagnosed as nondiagnostic at initial cytologic evaluation and 196 thyroid nodules underwent subsequent second or third FNAB. Twenty-seven thyroid nodules (18.9%) were underwent surgery and 116 thyroid nodules were considered as benign which were cytologically confirmed as benign and showed no remarkable change at follow-up US. US findings of total 143 thyroid nodules (123 benign nodules and 20 malignant nodules) in 138 patients (M: F = 20: 118; mean age, 50.5 years) were retrospectively reviewed. US features were including internal composition, echogenicity, margin, calcifications, shape and underlying echogenicity.III.RESULTSIn total, thyroid cancers were diagnosed in 20 nodules (14.0%, 19 papillary carcinomas and one minimally invasive Hurthle cell cancer). Lesion size varied from 3 to 40mm (mean, 10.4mm). Fourteen lesions were palpable and the others were incidentally found. The size of lesion was significantly associated with malignancy (P < 0.05). Only two sonographically probable benign nodules revealed malignancy (2.4%). Suspicious nodule on US showed thyroid cancer in 43.2%. Markedly hypoechogenicity, microlobulated or irregular margin, microcalcifications and taller-than-wide shape were

significant US findings that correlated with malignancy (P < 0.05). Diagnostic performance of ultrasound of initially nondiagnostic thyroid nodules was calculated as follow: sensitivity 90.0%, specificity 65.0%, positive predictive value 29.5 %, and negative predictive value 97.6%.IV.DISCUSSION Malignancy rates of thyroid nodules which were showed non-diagnostic result in FNAB was 14.0% in our study. Considering the management of thyroid nodules with nondiagnostic FNAB cytology, the US evaluation is a feasible method and useful in predicting malignancy. V.CONCLUSIONAlthough nondiagnostic cytologic result at initial FNAB, repeat FNAB is needed for sonographically suspicious nodules, due to 14% of malignancy rates in nondiagnostic thyroid nodules. However, follow-up US is more recommended rather than repeat FNAB for sonographically probably benign nodules. Sonographic findings of thyroid nodules with nondiagnostic results at FNABs are useful method to plan the management.