Thyroid carcinoma distinctively expresses intracellular fibronectin in vivo.

Fibronectin is a multifunctional protein that plays a role in tumor invasion. We immunohistochemically examined the in vivo expression of fibronectin in thyroid carcinoma in comparison with other carcinomas, such as hepatocellular carcinoma, transitional cell carcinoma and gastric adenocarcinoma. Intracellular localization of fibronectin was found in almost all cases of thyroid carcinoma. In contrast, hepatocellular carcinoma showed a lower expression rate and the other carcinomas were all negative. These results indicate that the intracellular expression of fibronectin is not a common phenomenon in carcinoma, but rather is distinctive for thyroid carcinoma.