['To verify whether immunohistochemistry might be useful in the distinction between a true laterocervical metastasis of an undetected thyroid carcinoma and a primary tumor outside the gland.', 'Galectin-3, cytokeratin 19, and HBME-1 were assessed in six cases (group A) of laterocervical masses harboring papillary thyroid carcinoma (PTC) but without a thyroid tumor, and in eight cases (group B) showing PTC both in the thyroid and in the laterocervical masses. In both groups, normal-looking follicles adjacent to the laterocervical neoplasia were present.', 'We found that the apparently normal follicles in group A were negative for all the antibodies, while group B showed strong and diffuse positive immunostaining. The neoplastic areas were always positive for all the antibodies in both groups.'] Does immunohistochemistry differentiate papillary thyroid carcinoma arising in ectopic thyroid tissue from secondary lymph node metastases?