Diagnostic tests can determine if a thyroid nodule is benign or malignant ; this information can help to guide treatment decisions. There are several diagnostic tests and each provides unique information about the thyroid nodule.

Thyroid nodules are common and occur in up to 50% of the adult population; however, less than 7% of thyroid nodules are malignant. High–resolution ultrasonography (US) is commonly used to evaluate the thyroid gland, but US is frequently misperceived as unhelpful for identifying features that distinguish benign from malignant nodules. Microcalcifications are one of the most specific US findings of a thyroid malignancy. Other useful US features include a marked hypoechogenicity, irregular margins, and the absence of a hypoechoic halo around the nodule. Lymphadenopathy and local invasion of adjacent structures are highly specific features of thyroid malignancy but are less commonly seen. The number, size, and interval growth of nodules are nonspecific characteristics. Suspicious US features may be useful for selecting patients for fine–needle aspiration biopsy when incidental nodules are discovered and when multiple nodules are present.  This study done to assess retrospectively ultrasound features of thyroid nodule in patient having differentiated thyroid cancer.