Anaplastic thyroid carcinoma associated with Graves' disease.

This report concerns a 79-year-old woman with coexisting anaplastic thyroid carcinoma (ATC) and Graves' disease (GD). The patient was referred to our clinic because of palpitation and a palpable mass on the left side of her neck. Thyroid function tests showed hyperthyroidism with elevated thyroid-stimulating antibodies. Ultrasonography of the thyroid demonstrated an adenomatous nodule-like marcated nodule (27.6 x 26.5 x 36.4 mm) with cystic degeneration inside the left lobe. (123)I thyroid scintigraphic imaging showed a cold area corresponding to the nodule with continuous uptake in the remaining thyroid tissue despite suppressed TSH levels. These findings led to a diagnosis of GD. On the other hand, the thyroid nodule could not be definitely diagnosed even after fine needle aspiration biopsy (FNAB) which produced findings suggestive of both papillary thyroid carcinoma and ATC. Open biopsy of the nodule showed an ATC. Regional lymph node metastases as well as multiple lung metastases, which could not be found at the initial visit, had been already developed by that time. Our case is pathophysiologically interesting because it suggests that GD or thyroid-stimulating antibodies (TSAb) may stimulate malignant transformation of differentiated carcinoma. It is also clinically important because it indicates that all thyroid nodules, particularly palpable cold nodules, associated with GD require careful management to detect malignancy because they are at higher risk of harboring malignancy.