Toxic adenoma and papillary thyroid carcinoma in a patient with Graves’ disease

A case of a very rare association of toxic adenoma and papillary carcinoma with Graves’ disease is presented. A 34-year-old woman developed Graves’ disease with mild ophthalmopathy. An ultrasound revealed diffuse thyroid enlargement with a hypoechoic pattern and a hypoechoic nodule with regular edges of 1.6 cm in diameter at the lower pole of the left lobe. A thyroid 131 I scintiscan showed a diffuse and homogeneous 131 I distribution. The 131 I uptake (RAIU) was elevated. One year later, while still on a low dose of methimazole, the patient had a recurrence of hyperthyroidism following an iodine load from a contrast agent. A further thyroid ultrasound confirmed the previously described pattern but showed a new hypoechoic nodule of 1.1 cm with irregular edges in the left lobe. A thyroid 131 I scintiscan this time demonstrated a hyperactive area localised in the larger nodule and a lower diffuse uptake of the remaining tissue. Because of the worsening of the symptoms of hyperthyroidism, the patient had a left lobectomy. On histological examination, the larger nodule was well encapsulated and showed the characteristics of a hyperfunctioning follicular adenoma. The smaller nodule was a typically unencapsulated papillary carcinoma. Several other microfoci of papillary carcinoma were also found in the adjacent tissue. Completion of thyroidectomy was therefore performed, followed by 131 I ablative therapy and thyroxine suppressive treatment. This observation suggests that the chronic abnormal stimulation of the thyroid gland by the thyroid-stimulating antibody (TSAb) may facilitate the neoplastic transformation of the thyrocytes in individuals with a critical genetic background.