LIN Jen-Der

Jen-Der LIN

Division of Endocrinology and Metabolism, Departments of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taiwan, R.O.C.

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Because thyroid or neck ultrasonography is a non-invasive diagnostic procedure and is less expensive, it has been used as a first-line examination tool in different thyroid disorders. In Taiwan, thyroid ultrasonography with fine needle aspiration cytology（FNAC）has been widely used for diagnosing thyroid nodules over the past 35 years. Stratification of the risk of malignant thyroid nodules is performed after history taking and physical examination. The characteristics of thyroid nodules can be classified as solid, mixed, and cystic lesions. Malignant features visible on thyroid ultrasonography include microcalcifications, hypoechogenicity, irregular margins, and a nodular shape that is taller than it is wide. In addition, perinodular and intranodular hypervascularity are suggestive of follicular thyroid carcinoma. For cases with a thyroid nodule larger than 1 cm or showing malignant features on ultrasonography, FNAC is recommended. In our experience, among 2,139 histopathologically proven thyroid cancer cases, 1,915 cases（89.5％）presented with a solid tumor and 40 cases（1.9％）presented with a cystic tumor. The ultrasonographic characteristics of malignancy are clearer in classical papillary thyroid cancer than in the follicular variant of papillary thyroid carcinoma. There were 71.1％vs. 16.0％cases with hypoechogenicity, 82.2％vs. 50.7％cases with micro- or macro- calcification, 36.8％vs. 21.8％cases with an ill-defined margin, 18.4％vs. 5.8％cases with a tall vs. a wide shape, 18.4％vs. 1.3％cases with extra-thyroid invasion, and 8.6％vs. 0％cases with lymph node enlargement in classical and the follicular variant papillary thyroid carcinoma, respectively. FNAC was used to make a diagnosis on the basis of the Bethesda system. There were 84.3％and 46.1％cases classified in category IV to VI in these two groups. Core needle biopsy is recommended in patients with malignancy or those suspected of malignancy, otherwise FNAC unlike thyroid origin. After excluding thyroid microcarcinoma（tumor size ≤ 1 cm）, the diagnostic rate of thyroid cancer with thyroid ultrasonography and FNAC（categories IV to VI）was 86.1％．