Objective: To investigate ultrasonographic features of benign and malignant thyroid nodules.

Materials and Methods: We compared ultrasonographic features and ultrasonography guided fine needle aspiration biopsy results of a total number of 71 patients (14 men, 57 women; mean age: 47±12) with adequate fine needle aspiration biopsies between June 2008 and June 2009. The features evaluated on ultrasonography were size, number, echogenicity (hypo-iso-hiper-mixed), shape (lobulated-nonlobulated), margin (well-ill defined), echotexture (homogenous-heterogenous), and presence of calcification (micro-macro-rim), hypoechoic halo, and cystic areas.

Results: The diagnosis of fine needle aspiration biopsies of 71 cases were benign, thyroiditis, suspicious for malignancy, malignant and follicular neoplasia in 49 (69%), 2 (2.8%), 7 (9.9%), 3 (4.2%), 10 (14.1%) cases respectively. We categorized the results of fine needle aspiration biopsies as benign (benign and thyroiditis) and malignant-suspicious (suspicious for malignancy, malignant and follicular neoplasia). Statistically significant findings (p<0.05) in malignant-suspicious group were hypoechogenicity (sensitivity, 55%; spesificity, 78%) on 11 (55%) patients and ill defined margins (sensitivity, 80%; spesificity, 50%) on 16 (80%) patients.

Conclusion: Hypoechogenicity and ill-defined margins are helpful criteria for discrimination of malignant from benign nodules. These criteria are also helpful at the selection of nodule in the fine needle aspiration biopsy.