Hashimoto's Thyroiditis

AKA: struma lymphomatosa

- transformation of thyroid tissue to lymphoid tissue

- most common inflammatory disorder of the thyroid

- most common cause of hypothyroidism

Etiology:

- autoimmune process caused by activation of CD4 T cells specific for thyroid antigens.  Innate and adaptive immune response against thyroid

Clinical Presentation

Hashimoto's thyroiditis is also more common in women (male:female ratio 1:10 to 20 ) between the ages of 30 and 50 years old. The most common presentation is that of a minimally or moderately enlarged firm granular gland discovered on routine physical examination or the awareness of a painless anterior neck mass, although 20% of patients present with hypothyroidism, and 5% present with hyperthyroidism (Hashitoxicosis). In classic goitrous Hashimoto's thyroiditis, physical examination reveals a diffusely enlarged, firm gland, which also is lobulated. An enlarged pyramidal lobe often is palpable.

Diagnostic Studies

- When suspected clinically, an elevated TSH and the presence of thyroid autoantibodies usually confirm the diagnosis.
- FNAB  indicated in patients who present with a solitary suspicious nodule or a rapidly enlarging goiter.
- Thyroid lymphoma is a rare but well-recognized, ominous complication of chronic autoimmune thyroiditis and has a prevalence 80 times higher than expected frequency in this population than in a control population without thyroiditis. Recent studies of clonal similarity indicate that lymphoma may, in fact, evolve from Hashimoto's thyroiditis.14
- Path: FNA sample will show Hurthle cells in conjunction with heterogeneous populations of lymphocytes

Treatment

Thyroid hormone replacement therapy is indicated in overtly hypothyroid patients, with a goal of maintaining normal TSH levels. The management of patients with subclinical hypothyroidism (normal T4 and elevated TSH) is controversial. Treatment is advised especially for middle-aged patients with cardiovascular risk factors such as hyperlipidemia or hypertension and in pregnant patients.15 Treatment also is indicated in euthyroid patients to shrink large goiters. Surgery may occasionally be indicated for suspicion of malignancy or for goiters causing compressive symptoms or cosmetic deformity.