1. ¹Laboratory of Pathology, Cliniques Universitaires de Bruxelles, Hôpital Erasme, Brussels, Belgium
2. ²Laboratory of Histopathology, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium
3. ³Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University, Munich, Germany
4. ⁴Department of Dermatology, School of Medicine, University of California, Davis, Sacramento, California

Correspondence: Isabelle Salmon, M.D., Ph.D., Laboratory of Pathology, Erasmus Hospital, 808 route de Lennik, B-1070 Brussels, Belgium; e-mail: isalmon@ulb.ac.be; fax: 322-555-4790.

Accepted 27 August 2002.

Abstract

Galectin-7 is associated with p53-dependent onset of apoptosis and proliferation control/differentiation in keratinocyte development. It is also up-regulated in chemically induced rat mammary carcinogenesis. Because the levels of expression of galectin-7 have never been investigated in thyroid tumors (in contrast to those of galectin-1 and -3 associated with malignancy), we initiated analysis of the expression of galectin-7 in benign and malignant thyroid lesions together with that of cytokeratin-19 (CK19), a marker already demonstrated to be useful in diagnosing this kind of lesion. The immunohistochemical expression levels were quantitatively determined by means of computer-assisted microscopy on a series of 84 thyroid lesions including 10 multinodular goiters, 32 adenomas, and 42 carcinomas. Our data clearly indicate a marked down-regulation of galectin-7 expression in a large proportion of adenomas (including the normomacrofollicular, microfollicular, and trabecular variants) if compared with carcinomas. In accordance with results of previous studies, a marked up-regulation of CK19 expression was observed in the thyroid carcinomas, and this contrasted in particular with the low CK19 expression observed in the microfollicular adenomas. Of importance for diagnostic implications, the combination of these two markers enabled our series of microfollicular adenomas (characterized by low galectin-7 and CK19 expression) to be efficiently distinguished from the encapsulated follicular variant of papillary thyroid carcinomas (high galectin-7 and CK19 expression).