Follicular carcinoma of the thyroid with massive angioinvasion: extension of tumor thrombus to the heart.

Angioinvasion is a well documented microscopic characteristic of follicular carcinoma of the thyroid. Patients with untreated tumors may die from local invasion or metastases to the lungs, bones, or other organs. A less well recognized cause of morbidity and death from this neoplasm is angioinvasion of cervical veins with direct extension into the great veins of the chest, to the heart. Six instances of this complication have been reported previously. The most common clinical presentation of patients with neoplastic thrombus within the great veins is the superior vena cava syndrome. In each case the patient died as a result of the vascular or cardiac involvement, shortly after diagnosis. The patient reported is the first in which follicular carcinoma with extensive angioinvasion was treated. A clinical diagnosis of superior vena cava syndrome was confirmed by angiographic studies. Resection of the primary thyroid tumor and the angioinvasive extension to the heart plus 131I therapy have controlled the malignancy for at least 3 years.