Abstract
Clinically, a diffuse, firm goiter with pyramidal lobe enlargement, and without signs of thyrotoxicosis, should suggest the diagnosis of Hashimoto's thyroiditis (HT). The association of goiter with hypothyroidism is almost diagnostic. The thyroid stimulating hormone (TSH) is the sensitive marker of hypothyroidism and diagnosis of subclinical hypothyroidism. Thyroid perioxidase antibodies (TPO-Ab) and, less frequently, thyroglobulin antibodies (Tg-Ab) are elevated in the serum of patients with HT. Ultrasound may display an enlarged gland with normal texture, focal, or diffuse glandular enlargement with coarse, heterogenous, and hypo-echoic pattern, or a suggestion of multiple ill-defined micro-nodules. Color Doppler shows extensive hyper-vascularity. Histologically, the thyroid gland shows diffuse lymphocytic and plasma cell infiltration with formation of lymphoid follicles. Atrophy of the thyroid parenchyma is usually evident. It also reveals scant colloid, and a few epithelial cells, which may show Hurthle cell change. This chapter explores the diagnosis of Hashimoto's disease.