This image shows a large lymphoid follicle with prominent germinal center. It is surrounded by small atrophic thyroid follicles showing oxyphilic change. Hashimoto thyroiditis, also known as struma lymphomatosa is predominantly seen in women over age 40 (female:male ratio is 10 to 20:1) but may be seen in children. It the most common cause of hypothyroidism not related to Iodine deficiency. The gland is slowly destroyed by immune-mediated injury.