Immunohistochemistry done for gross pathology of thyroid cancer has a wide range of roles and is important for early diagnosis of thyroid cancer, differentiation of subtypes, determining the presence of lymph node metastasis, the degree of differentiation, and the selection of target drugs for advanced patients. Which can be used to help the differential diagnosis of the following different types of cancer: 1. Differentiation between benign and malignant follicular tumors. 2. Differentiation of classic papillary thyroid carcinoma and follicular subtype. 3. Differentiation of solid and poorly differentiated thyroid carcinoma. 4. Differentiation of mesenchymal carcinoma from sarcoma and squamous cell carcinoma. The classification of thyroid carcinoma is determined by the morphology of the tumor sections observed by the pathologist under the microscope. However, different types of tumors may have very similar morphology under the microscope, and therefore immunohistochemistry is needed to assist in the diagnosis. Immunohistochemistry allows the pathologist to learn more about the proteins within the cells.