Background: Fine-needle aspiration biopsy is the most important procedure for differentiating benign thyroid nodules from malignant ones. Traditionally, findings of fine-needle aspiration biopsy are divided into four categories: nondiagnostic, benign lesions, suspected cancer, and malignant lesions. Group suspicious for cancer largely involves follicular neoplasms as well as lesions with cytological features of malignancy.
Objective: The purpose of this study was to establish the value of ultrasound-guided fine-needle aspiration biopsy in the diagnosis of nonpalpable thyroid cancer and to assess the frequency of malignant disease in the group of suspected cancer.
Patients and methods: A total of 184 patients with nonpalpable thyroid nodules (less than 1.5 cm in diameter) were examined by means of ultrasound-guided fine-needle aspiration biopsy. Patients were included in the study based on sonographic findings implicating possible malignant nature of nodules. RESULTS. During 1997-2002, 204 ultrasound-guided fine-needle aspiration biopsies of thyroid nodules were performed; findings were nondiagnostic in 5.9% of cases. In 59.8% of cases, cytological examination revealed benign lesions; in 11.8%, suspected cancer; and in 22.5%, malignant lesions. Eighty-five patients underwent subsequent surgery with histological examination of specimens obtained. In 45 cases, cytological diagnosis of malignant or suspected thyroid cancer was confirmed by histological examination after surgery.
Conclusion: We conclude that ultrasound-guided fine-needle aspiration biopsy has a high accuracy in the diagnostic evaluation of nonpalpable thyroid nodule with cytological features of malignancy. However, fine-needle aspiration biopsy is not effective diagnostic method for differentiating benign thyroid nodules from malignant ones in follicular neoplasm group.