Thyroid carcinoma in patients with Graves' disease: an institutional experience.

Graves' disease (GD) is an autoimmune disorder characterized by diffuse hyperplasia and excessive production of thyroid hormone. The association between thyroid carcinoma and GD is controversial. The prevalence of thyroid carcinoma was investigated in patients with GD who underwent thyroidectomy for thyroid nodular lesions or GD from 1994 to 2013 at our institution. Three hundred and forty-seven patients were placed into two groups: Graves' disease with nodular lesions group (group GN) included 85 patients who had thyroidectomy for nodular lesion, and Graves' disease group (group G) included 262 patients who had thyroidectomy for hyperthyroidism. There were 59 patients with thyroid carcinomas in the 85 patients (69 %) of group GN, including 3 follicular carcinomas (5 %), 1 poorly differentiated carcinoma (2 %), and 55 papillary thyroid carcinomas (93 %). Among the 55 papillary thyroid carcinomas, 19 cases were papillary thyroid microcarcinomas (34 %); and 5 cases of tall cell variant (9 %) were identified. There were 8 cases with lymph node metastasis (14 %), 6 cases with lymphovascular invasion (10 %), and 12 cases with extrathyroidal invasion (20 %). In addition, 24 carcinomas showed multiple foci of tumor (41 %). In contrast, 51 patients (19 %) of 262 patients in group G had carcinoma, including 2 follicular carcinomas (4 %) and 49 papillary thyroid carcinomas (96 %). In the 49 cases of papillary thyroid carcinomas, 47 cases were microcarcinomas (96 %); and 2 cases of tall cell variant (4 %) were found. There were no lymph node metastasis or lymphovascular and extrathyroidal invasion, but 11 cases (22 %) demonstrated multiple carcinoma foci. In conclusion, thyroid nodular lesions in patients with GD should raise a high suspicion of carcinoma, and these lesions are frequently clinically significant tumors. Incidental thyroid carcinomas in patients with GD are not uncommon, but most of them are low-risk papillary thyroid microcarcinoma without lymph node metastasis or lymphovascular and extrathyroidal invasion.