Papillary thyroid carcinoma is the most common and least malignant. It accounts for about half of thyroid cancer and is more common in children or young (before 40 years old) female patients. Some patients had neck X-rays in childhood. Tumors grow slowly and can be confined to the thyroid gland for several years. Lesions can spread from the primary site to other parts of the gland and local lymph nodes through lymphatic vessels in the gland, or they can be localized for several years, so it is easy to ignore their nature. Pathologically, well-differentiated columnar epithelium is papillary, with clear nucleus and eosinophilic cytoplasm, and concentric calcium deposits are often seen. Clinically, there are few manifestations except nodules or local lymphadenopathy. Thyroid radionuclide scan showed cold nodules; X-ray examination of the neck can show tiny spots or concentric calcium deposits in the tumor. Papillary carcinoma can be stimulated by TSH and reduced by thyroid hormone. If the capsule is intact without metastasis, the life expectancy is normal. If there is vascular invasion, the survival rate of one third of patients is about 10 year. Treatment: surgical resection and postoperative radiotherapy and chemotherapy.