A fifty-eight- year old woman with a history of subtotal thyroidectomy 20 years before was admitted to the hospital because of back ache. Chest computed tomography revealed a mass lesion destroying the ribs and multiple metastatic lesions scattered bilaterally in the lungs. Transthoraclc blopsy was performed and blopsy findings were consistent with follicular thyrold cancer metastasis. 131I whole body scan showed uptake in mulilple sites of the lungs and in the thyroid as well. The patient was euthyroid. A renal mass, observed on ultrasound examination was Investigated by blopsy and pathological examination showed metastatic follicular carcinoma. Subsequently, the patient underwent total thyroldectomy. Pathological examination of the thyroid revealed no remarkable abnormality and malignancy could not be detected. A therapeutlc dose of 160 mCI 131I was given, on the posttreatment scan the activities on the lungs and kidneys persisted. After the treatment period, TSH became suppressed and free T4 and T3 levels rose above the normal range without L-thyroxin being given. Thyroid hormones persisted in the thyrotoxlc range throughout the 2 month period though clinically silent. Then TSH rose to the normal range and a TSH- suppressive dose of L-T was administered.
Keywords: Thyrotoxicosis, thyroid neoplasms