Thyroid gland inflammation. Light micrograph of a section through thyroid gland tissue in a case of Hashimoto's thyroiditis. Thyroiditis, inflammation of the thyroid, has several different forms. Here, an autoimmune response, large numbers of certain white blood cells dominate the image. The whole gland is affected and production of the metabolic hormone thyroxine decreases (hypothyroidism). If the gland swells excessively (goitre) it will need to be surgically removed. The hypothyroidism is treated by thyroid hormone replacement.