THYROID HEMIAGENESIS ASSOCIATED WITH GRAVES' DISEASE: A CASE REPORT AND REVIEW OF THE LITERATURE.

INTRODUCTION: Thyroid hemiagenesis (TH) is a congenital developmental disorder. Most cases are euthyroid although hyperthyroidism, hypothyroidism, and malignancy may develop. We present a case of hemiagenesis with Graves' disease (GD) and review the literature about the association. CASE REPORT: A 45-year-old female patient was admitted to the endocrinology department due to nausea and diarrhea. Her past medical history revealed hyperthyroidism diagnosed a year ago. On thyroid examination, right thyroid lobe was palpable, but left lobe and isthmus were not. Physical examination involving other organ systems was unremarkable except for fine tremor of the hands. Thyroid function tests revealed a high level of free T4 and T3 with a low serum TSH. Thyroid antibodies were all positive. Left lobe and isthmus were invisible on thyroid ultrasonography (US) and the right thyroid lobe measuring 44x18x12 mm was diffusely heterogeneous in echo texture. Thyroid scan using Technetium-99m showed increased homogeneous tracer uptake in the right lobe. The patient was diagnosed with TH and GD. DISCUSSION: In case of unilateral increased uptake on scintiscan, GD with hemiagenesis must be kept in mind in the differential diagnosis of autonomous solitary adenoma, postinflammatory atrophy of thyroid in Hashimoto's disease, focal or unilateral subacute thyroiditis, and primary or metastatic carcinoma. It is prudent to do thyroid ultrasound along with scintigram. US is a valuable tool for the quick diagnosis of TH and differential diagnosis from other causes.