Thyroid hemiagenesis, Graves' disease and differentiated thyroid cancer: a very rare association: case report and review of literature.

OBJECTIVE Thyroid hemiagenesis is a rare congenital disorder characterized by the absence of a lobe and/or of isthmus. Studies on the association between thyroid hemiagenesis, Graves' disease and differentiated thyroid cancer are rare. CASE PRESENTATION We describe the medical and surgical history of a patient in whom a molecular evaluation was performed. A 36-year-old man presented with symptoms and signs of hyperthyroidism of a few months' duration. Hyperthyroidism was confirmed biochemically and anti-TSH-receptor antibodies were positive. Thyroid ultrasonography showed no left lobe and demonstrated a diffused enlargement of the right lobe; an ipoechoic, non-homogenous nodule 15 millimeters in size was identified in the middle part of the lobe. A 99mTc-pertechnetate thyroid scintigraphy (111 MBq) confirmed thyroid hemiagenesis due to the absence of the left lobe. Treatment with methimazole (30 mg/day) was started. As the patient's hyperthyroidism improved, he underwent fine-needle needle aspiration cytology (FNAC) of the right nodule. Cytology was suspicious for malignancy (THY4) and the patient was referred for surgery. Histopathological findings revealed a papillary thyroid carcinoma. The molecular analysis did not show PAX8 or TSHR mutations in the thyroid tissue nor mutations of BRAF, H-RAS, N-RAS or K-RAS genes in the tumor. CONCLUSION Though thus far studies on the association of thyroid hemiagenesis, Graves' disease and differentiated thyroid cancer are extremely rare, the possibility of the development of thyroid cancer must be taken into account in patients affected by thyroid hemiagenesis and the nodular variant of Graves' disease.