Results of preoperative ultrasound guided fine needle aspiration biopsy ofsolitary thyroid nodules as compared with the histology - A retrospective analysis of 538 patients

Aim: The goal of this study was to assess the accuracy and limitations of u ltrasound guided fine-needle aspiration biopsy (ug-FNAB) of solitary thyroi d nodules. Methods: The ug-FNAB results of 538 patients with solitary thyro id nodules, who afterwards underwent thyroid surgery, were compared retrosp ectively with the histology. Patients with multinodular goiter were exclude d from the study. Ug-FNAB was performed on growing and/or hypoechoic and/or hypofunctional nodules. The ug-FNAB results were grouped as follows: group 1 : malignant (n = 44); group 2: malignancy cannot be ruled out (n = 173); group 3: non-malignant (n = 296), group 4: inadequate (n = 25). Results: W hen the cytological results of group I and group 2 were interpreted as bein g malignant and those of group 3 as being benign, sensitivity, specificity and accuracy of ug-FNAB were 96.7%, 65.8% and 69.5% respectively. The 62 th yroid carcinomas (TC) biopsied presented in 59 cases a suspicious or malign ant cytology (95.2%). The smallest TC diagnosed by ug-FNAB had a diameter o f 0.5cm and 36.4% of all papillary TC ! 1 cm displayed stage pT4. The histo logy verified a TC in 18 cases out of the 173 ug-FNABs in group 2. Non-mali gnant ug-FNABs were confirmed by histology in 294 patients (99.3%) in group 3. In 4.65% of the ug-FNABs inadequate material was aspirated. Conclusion: Nodules with non-suspicious ug-FNAB results can be safely followed-up by s onography, as the cytological diagnoses were verified in more than 99% by h istology. Papillary TC can be diagnosed with ug-FNAB very accurately. As st age pT4 was present in more than one third of patients with papillary TC ! I cm, ug-FNAB is also recommended for thyroid nodules 0.5-1 cm in diameter located adjacent to the thyroid capsule. However, microfollicular prolifera tions remain the limitation of ug-FNAB, as the cytology cannot distinguish between benign adenoma and follicular TC.