Successful Visualization of an Indeterminate Hepatic Metastasis From Thyroid Carcinoma Using Contrast-Enhanced CT and Contrast-Enhanced Ultrasound

Abstract

A 76-year-old female underwent hemithyroidectomy in 2009 because of a thyroid tumor that was suspected to be papillary thyroid carcinoma. Histological examination revealed the tumor to be poorly differentiated papillary thyroid carcinoma with vascular invasion but without lymph node metastasis or local invasion. Serum levels of thyroglobulin (Tg) remained high ( 200 ng/mL) and increased thereafter postoperatively. However, no metastatic lesions were detected by chest-to-abdominal plain computed tomography (CT), bone scintigraphy, brain magnetic resonance imaging, upper abdominal ultrasound, or positron emission tomography-CT (Figure 1A). In addition, 131-I whole body scans after total thyroidectomy were negative (Figure 1B). Although not strictly indicated due to the high basal Tg level, a stimulation test was performed with 0.9 mg of recombinant human TSH for 2 consecutive days. Serum levels of Tg increased from 2853 to 11 579 ng/mL, suggesting the existence of viable thyroid cancer tissues. The patient underwent contrast-enhanced CT (CECT) to explore the rare sites of metastasis such as the pancreas (1) and bladder (2), which revealed a hepatic mass (Figure 2A). Contrast-enhanced ultrasound (CEUS) with a perflubutane microbubble agent (3) was used to successfully visualize the hepatic lesion. This was because the tumor had been undetectable 3 years before and was still indeterminate in the plain ultrasound (Figure 2, B and C). A diagnosis of thyroid carcinoma metastasis to the liver was made because of positive Tg and thyroid transcription factor-1 (TTF-1) immunostaining in the hepatic tumor specimens obtained by CEUS-guided tumor biopsy (Figure 2, D–F). The metastatic tumor was treated with transcatheter arterial chemoembolization in 2012, and serum levels of Tg dropped from 5865 to 2810 ng/mL within 2 months, although the tumor was not decreased significantly (Figure 2A, inset). This report suggests that indeterminate hepatic metastasis from thyroid carcinoma can be visualized by employing appropriate imaging modalities, including CECT and CEUS.