Identification of Metastatic Carcinoma in the Thyroid by Determination of Thyroglobulin Level in Aspirates and Ultrasonic Findings

Abstract

A 49-year-old female with a metastatic renal cell carcinoma to the thyroid is presented. The thyroglobulin (Tg) level in tumor aspirates of this patient was 37.3 μg/l, while that of 49 patients with primary thyroid nodules ranged from 2.0 × 10³ to 7.5 × 10⁸ μg/l. Ultrasonogram of the thyroid demonstrated a well-demarcated oval nodule with a cystic region, the solid part of which was hypoechoic and homogeneous. However, similar ultrasonic findings were observed in only 1.1% of 1, 054 patients with primary thyroid nodules. Determination of Tg in tumor aspirates and ultrasonography of the thyroid may contribute to the differentiation of metastatic thyroid nodules from primary thyroid nodules.
(Internal Medicine 32: 46-49, 1993)