Overview Papillary carcinoma is the most common type of malignant tumor of the thyroid gland. It accounts for 50-70% of cases. In papillary carcinoma foci, 1/3-1/2 of patients have lymphocytic infiltration. There is usually no lymphocytic infiltration in the normal thyroid tissue outside the lesion. Microscopic foci of dissemination are often seen in resected specimens of papillary carcinoma quite distant from the primary focus or even in the contralateral glandular lobe, and have been reported in 90% of specimens on close examination, making it difficult to distinguish between intra-glandular lymphatic tract dissemination and multicentric focal tumors. Papillary carcinoma has a marked tendency to infiltrate regional lymph nodes. Regional lymph node metastases are evident in approximately 50% or more of cases at the time of surgery. The rate of metastasis in the cervical lymph nodes can be as high as 90% with careful examination of the excised specimen. Distant metastases from papillary carcinoma usually occur in the lungs, skull, and soft tissues. Regardless of the structure of papillary carcinoma, distant metastases are often a mixture of papillary and follicular or predominantly follicular forms. Diagnosis Papillary carcinoma often presents clinically as an isolated nodule in the thyroid region, mostly over 1 cm in diameter. The masses are hard, with unclear borders, and have little up and down mobility with swallowing movements, and are not easily pushed, and have poor basal mobility. On ultrasound, most of the nodules are solid, and a few are cystic or cystic solid. Nuclear examination is mostly cold nodules, and a few are cool or cold nodules. Occult papillary carcinoma is also not uncommon, and many cases have been reported in recent years both at home and abroad. However, 20 years ago. It was still mainly limited to autopsy.