Primary lymphoma of the thyroid, the association with Hashimoto's thyroiditis

This paper reviews the cases of thyroid lymphoma seen at one centre to assess the relationship between autoimmune thyroiditis and the subsequent development of thyroid lymphoma. Twenty two cases of thyroid lymphoma were seen over a 10 year period; 5/22 (23%) had previously been diagnosed as having Hashimoto's thyroiditis. The series comprised 18 women and four men; mean (range) age at presentation was 64 (26-85) years. All patients presented with a rapidly enlarging goitre and 13/22 (59%) underwent surgical excision prior to diagnosis of lymphoma. Nineteen of 22 (86%) patients underwent radiotherapy. The 5-year mortality for stage IE disease was 43%, survival appeared to be unrelated to previous Hashimoto's thyroiditis or to surgical resectability. The histological differentiation between pre-existing thyroiditis and thyroid lymphoma is often difficult and may lead to an underestimate in the reporting of the association. A prospective study of serial autoantibody assays in patients with Hashimoto's thyroiditis may be useful in predicting the onset of lymphomatous change in this condition.