Introduction A condition characterized by the autoimmune destruction of the thyroid Pathophysiology the inflammatory reaction is a combination type II and type IV hypersensitivity reaction type II hypersensitivity reaction anti-TSH receptor antibodies are formed that inhibit thyroid hormone release opposite of Grave's disease anti-microsomal and anti-thyroglobulin antibodies are formed that lead to destruction of thyroid stroma do not confuse with anti-mitochondrial in primary biliary sclerosis type IV hypersensitivity reaction CD8 cells directly destroy thyroid tissue CD4-attracted macrophages destroy thyroid tissue Genetics association with HLA-DR3, DR5 genotype Associated conditions chromosomal aneuploidies Presentation Symptoms hyperthyroidism seen early in the disease course consequence of thryoid tissue destruction which releases stored thyroid hormones hypothyroidism seen later in the disease course after pre-formed thyroid hormone stores are released there is a decreased release as a result of impaired production Physical exam moderately enlarged, non-tender gland Evaluation Histology lymphocytic infiltrate germinal follicles Hürthle cells (eosinophilic-staining cells) fibrosis Treatment Pharmacologic thyroid hormone supplementation Complications Primary B-cell lymphoma of thyroid increased risk of primary B-cell lymphoma of thyroid