Metastatic Follicular Carcinoma Associated With Hyperthyroidism

Abstract

A 68-year-old man with metastatic follicular thyroid carcinoma had T3 hyperthyroidism. A bone scan showed intense uptake in the thyroid and multiple areas of increased uptake in the skeleton. Hyperthyroidism persisted after total thyroidectomy. Treatment with I-131 induced a transient state of euthyroidism lasting approximately 9 months. Further tumor growth and relapse of hyperthyroidism eventually occurred and the patient died 25 months after surgery. Molecular and cytogenetic analyses were performed. No mutations were detected of either of the thyrotropin receptor or of the alpha subunit of the stimulatory guanine-nucleotide-binding proteins. Hyperthyroidism was unlikely the result of thyroid-stimulating receptor antibodies. Comparative genomic hybridization analysis showed that the tumor was characterized by multiple chromosomal imbalances. This is an unusual case of follicular thyroid carcinoma with initial high I-131 uptake by the thyroid and bone metastases and concurrent hyperthyroidism. Despite the increased I-131 uptake in the tumor, I-131 treatment only transiently controlled the hyperthyroidism and had no effect on tumor size. The cause of hyperthyroidism remained unknown. T3 predominance was unlikely the result of type 2 deiodinase overexpression because loss of genetic material was demonstrated at chromosome 14 long arm, where type 2 deiodinase is mapped.