ObjectiveTo describe an unusual patient with thyroid carcinoma who had metastatic pulmonary nodules that regressed transiently during the active phase of Graves’ disease. MethodsThe clinical, pathologic, and laboratory findings in a female patient with thyroid carcinoma, pulmonary lesions, and Graves’ ophthalmopathy are presented. In addition, the patient’s clinical course and results of serial studies are reviewed. ResultsA 62-year-old woman underwent excision of a follicular carcinoma of the thyroid and then total thyroidectomy in 1984. Two years later, chest radiography disclosed multiple pulmonary lesions; open-lung biopsy revealed follicular carcinoma. Thyroglobulin determinations continued to increase, and computed tomography of the chest showed an increase in the size and number of pulmonary nodules. Clinically, the patient remained unchanged until 4 years postoperatively, when she noted rapid onset of diplopia, proptosis, and diminished visual acuity. During this time, a thyroid-stimulating immunoglobulin assay was strongly positive, thyroglobulin levels were decreased, and computed tomography and radiography of the chest showed evidence of tumor regression. Orbital decompression partially restored vision, and the inflammatory signs decreased gradually. Concurrently, the thyroid-stimulating immunoglobulin level declined, the thyroglobulin level increased, and the pulmonary lesions increased in size and number. The patient ultimately died of metastatic disease. ConclusionThe reduction in size of the pulmonary nodules and decrease in thyroglobulin levels when the thyroid-stimulating immunoglobulin level was high and the regrowth of lesions when it declined suggest a causal relationship. The hypothesis of an operative autoimmune factor cannot be substantiated without serologic evidence in this case but should prompt physicians to search for other such occurrences. (Endocr Pract. 2000;6:264-267)