Metastatic follicular carcinoma associated with hyperthyroidism.

Purpose: A 68-year-old man with metastatic follicular thyroid carcinoma had T3 hyperthyroidism.

Material And Methods: 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.

Results: 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.

Conclusions: 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.