Follicular subtype of papillary thyroid cancer is one of the subtypes of papillary thyroid cancer. Thyroid cancer can be categorized into papillary, follicular, undifferentiated, and medullary carcinomas. Papillary carcinoma is the most common type of thyroid cancer, accounting for more than 90% of cases. Its pathologic changes are the characteristic hallmarks for diagnosing papillary carcinoma. If a follicular structure is seen under the microscope, but the cytoplasm is filled with granulomas (a characteristic pathologic change of papillary thyroid cancer), the diagnosis of papillary carcinoma is also made, not follicular carcinoma. Subtypes of papillary thyroid carcinoma include: diffuse sclerosing papillary carcinoma, diffuse follicular papillary carcinoma, high columnar cell papillary carcinoma, trabecular papillary carcinoma, eosinophilic papillary carcinoma, peripheral papillary carcinoma, and microscopic papillary carcinoma. Diffuse follicular papillary carcinoma is more common in young people, with invasive growth and diffuse involvement of the entire thyroid lobe, and is easily misdiagnosed as goiter. Histologically, follicular structures predominate, but the nucleus is characteristic of papillary carcinoma. It is easy to metastasize to lymph nodes, lungs and bones, and is sensitive to radioactive iodine therapy. For specific diagnosis, it is necessary to go to regular hospitals to take a comprehensive diagnostic approach, to evaluate all aspects, and finally to clarify the diagnosis.