Simultaneous occurrence of Graves’ disease in eutopic and ectopic thyroid tissues: A case report and review of literature
A 35-year-old married woman presented to our department of Nuclear Medicine with chief complaints of palpitations, tremors, increased sweating, increased frequency of stools, and weight loss. The patient was non-smoker, had two children a male and a female aged 14 and 12 years respectively. At the time of presentation the patient was non-lactating and not pregnant. In drug history, patient gave history of treatment with anti-thyroid medication (Carbimazole and Propranolol). On her own, the patient discontinued these drugs 4 months before the current symptoms. At presentation, she had a regular pulse of 104/min. Her weight was 47 kg. She had only mild visible proptosis. There was a transverse surgical scar in the neck. Thyroid was not visible or palpable. There was no other swelling in the neck. There was an abdominal surgical scar on right side (post cholecystectomy) and rest of the general and systemic examinations were unremarkable. Her serum free tri-iodothyronine (FT3) was 3.98 pg/ml (normal, 1.7-4.2 pg/ml), and FT4 was 2.30 ng/dl (normal, 0.70-1.80 ng/dl). Her thyroid stimulating hormone (TSH) was less than 0.01 μIU/ml (normal, 0.30-5.5 μIU/ml). Anti TPO antibodies were 690 U/ml (0-60 U/ml). The 24 h radioactive iodine-131 uptake of thyroid was elevated at 72%. Her chest X-ray was reported normal. The Endocrinologist referred her for radioiodine treatment of her hyperthyroidism. A thyroid scan done 15 min after intravenous injection of 185 MBq of Technitium-99 m sodium pertechnetate revealed a eutopic thyroid gland with relatively smaller right lobe and a left lobe with marked tracer uptake. The salivary glands were suppressed. In addition to these findings an abnormal area of marked uptake was seen in the right upper mediastinum that appeared to be an ETT []. A non-contrast computed tomography (CT) scan revealed both lobes of a eutopic thyroid gland with an ectopic thyroid gland in the right superior aspect of anterior mediastinum []. A diagnosis of Graves’ disease involving the eutopic as well as the ectopic mediastinal thyroid was confirmed. The patient was subsequently administered 370 MBq (10 mCi) of Iodine-131 solution orally 5 weeks post I-131 therapy patient was cured of her thyrotoxic symptoms and complained of lethargy and puffiness of face. Her TSH levels were reported as 117.63 μIU/ml. A Tc-99m sodium pertechnetate thyroid scan confirmed thyroid ablation []. Her post Iodine-131 hypothyroid symptoms were controlled by replacement dose of oral thyroxine.