The occurrence of lymphoma in patients with long-standing hyperthyroidism.

I N EXPERIMENTAL ANIMALS, thyroxin administration leads to hyperplasia of lymphoid tissue, and there is suggestive evidence that the presence of thyrotoxicosis increases the incidence of lymphoid tumors and shortens the survival time of the tumor bearing host ( of. references 26-42 ) . In man, hyperthyroidism, particularly Graves’ disease, is frequently associated with lymphoid hyperplasia manifested by lymphocytosis, lymph node enlargement, and splenomegaly ( cf. references 2-24 ) . The development of a lymphosarcoma in a patient with long-standing Graves’ disease was described for the first time in 1956 and was thought to be coincidental.1 Additional clinical evidence to implicate over-activity of the thyroid as a possible etiologic or contributory factor in the development of lymphomas and allied diseases in man has not been reported to date. The present report, which is intended to stimulate interest in this area, is a summary of a case history previously published and of five additional patients observed with long-standing hyperthyroidism in whom a lymphoma was diagnosed at a later date.