In addition to the varieties of thyroiditis already mentioned, which are diseases specifically of the thyroid gland, generalized or systemic diseases may also involve the thyroid gland (24). The lesions of sarcoid may appear in the thyroid gland of patients with systemic sarcoidosis, and huge deposits of amyloid occasionally causes goiter in amyloidosis. Painless thyroiditis has been noted in a woman with rheumatoid arthritis and secondary amyloidosis infiltrating the thyroid gland (130). Radiotherapy for tonsillar carcinoma has been reported to result in thyroiditis (131) and radiation during 131 I therapy produces thyroiditis, which is occasionally symptomatic. This situation is discussed in Chapters 11 and 18. Irradiation to the thyroid during therapy for breast cancer or lymphoma can also induce hypothyroidism. Therapy should be directed toward the primary disease rather than the thyroid, but administration of thyroid hormone may be necessary if destruction of thyroid tissue is sufficient to produce hypothyroidism. Finally, surgery to the neck has been reported to cause thyroiditis but this is rare (132,133).