•The etiology of Hashimotos thyroiditis is unknown.

•While the precise pathogenesis is unknown, it is believed that Hashimotos thrioditis represents a disease of auto-immune origin.

•It occurs most frequently in middle aged women.

•Commonly associated with other diseases of presumed autoimmune nature such as pernicious anemia, SLE and diabetes mellitus.

•Strongly associated with HLA-DR3 and -DR5.

•Clinically the disease presents as a painless goiter or may present as a nodule due to asymmetric growth.

•Functionally, the patient may be metabolically normal, hyperthyroid or hypothyroid.

•Usually there is progressive hypothyroidism.

•Increased risk for development of B-cell lymphoma.

•Grossly the thyroid is initially 2 to 3 times the size of a normal thyroid.

•The cut surface may show replacement of the normal glistening reddish brown with areas of pale gray somewhat fibrotic tissue reminiscent of a fibrotic lymph node.

•Histologically, there is replacement of the thyroid tissue with lymphoid tissue, which may show organization into typical lymphoid follicles.

•Many acini may be surrounded by oncocytes (H•rthle cells) which have abundant brightly eosinophilic granular cytoplasm.

•As the disease progresses, much of the thyroid may be replaced by scar tissue.

• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1126

• Current literature from PubMed at National Library of Medicine