Thyroiditis, if it is acute suppurative thyroiditis, clinical manifestations include fever, local pain in the thyroid, tenderness on palpation, and a hard texture of the thyroid. Examination will show an increase in white blood cells. Subacute thyroiditis may also present with mild fever or high fever and local pain in the thyroid, but compared to suppurative thyroiditis, the increase in white blood cell levels is not as significant in subacute thyroiditis. If it is autoimmune thyroiditis, there may not be obvious symptoms clinically; there may be enlargement of the thyroid, and the thyroid may feel tougher upon palpation. As for thyroid cancer, clinically, if it does not cause hyperthyroidism or hypothyroidism, there are no specific symptoms. When the cancerous tumor is large, there may be an enlargement of the thyroid, the texture of the enlarged thyroid will be very hard, and there will be notable local adhesions. Of course, the main difference can be detected and diagnosed through an ultrasound examination.