Evaluation of thyroid tumors is based on visualization and palpation of the thyroid and regional lymph nodes. Indirect laryngoscopic evaluation of vocal cord motion is essential. Various imaging methods can provide additional useful information, including radionuclide thyroid scans, ultrasonography, computer-assisted tomography (CT), and magnetic resonance imaging (MRI) scans. When cross-sectional imaging is utilized, MRI is recommended to avoid contamination of the body with iodine contrast agent applied systemically during CT, which delays the use of radioactive 131I after surgery. The diagnosis of thyroid cancer must be confirmed by needle biopsy of the tumor or surgical biopsy. Further information on clinical staging can be obtained from biopsies of lymph nodes or other local or distant sites that can be metastasized. All information that can be obtained before the first treatment should be utilized. Pathologic staging Pathologic staging requires the application of all information obtained in clinical staging and in histologic examination of surgically resected specimens. The assessment of the surgeon must also be included for incompletely resected residual tumors that are visible to the naked eye. Regional lymph nodes Regional lymph node metastases are common in thyroid cancer, but are not as prognostically significant in highly differentiated tumors (papillary, follicular) as in medullary carcinomas. In patients with carcinomas of different degrees of differentiation, the adverse prognostic impact of lymph node metastases is seen only in the higher age groups. The first station of metastatic lymph nodes consists of the paraglottic, paratracheal and anterior laryngeal (Delphian) lymph nodes, which are adjacent to the thyroid gland and located in the middle of the neck and are usually described as group VI. The next lymph nodes metastasize to the middle and lower groups of internal jugular vein lymph nodes, supraclavicular lymph nodes and (usually rare) the superior group of internal jugular vein lymph nodes and paraspinal lymph nodes. Submandibular and subchin lymph node metastases are rare. Upper mediastinal lymph nodes (group VII) are susceptible to metastasis both anteriorly and posteriorly. In those with extensive lateral cervical metastases, metastases to the retropharyngeal lymph nodes are often seen. Bilateral cervical lymph node metastases are common. n grading is composed as follows: station I (central neck/group VI), as N1a; and lateral cervical region and/or upper mediastinum as N1b. lymph node metastases should also be described by accepting the grouping of involved lymph nodes in the neck. Lymph node metastasis in medullary carcinoma, although following a similar pattern, has an extremely poor prognosis. For pN accuracy, histology for elective neck clearing will usually include more than 6 lymph nodes, and histology for radical neck clearing or modified radical total neck clearing will usually include more than 10 lymph nodes; negative pathology of less than these numbers of lymph nodes is still classified as pN0. Distant metastases Distant metastases follow hematologic routes, such as lung and bone, and many other sites can be involved.