Galectin-3 expression in papillary thyroid carcinoma: Relation to histomorphologic growth pattern, lymph node metastasis, extrathyroid invasion, and tumor size

Background. Galectin‐3 has been recently recognized as a promising presurgical marker of thyroid malignancy. Methods. Galectin‐3 expression was examined immunohistochemically in 202 specimens of papillary thyroid carcinoma (PTC) in relation to histomorphologic subtypes and clinicopathologic data. Results. The sensitivity of galectin‐3 immunostaining versus conventional histology was 98% (100 of 102) for classical PTC, 85.2% (46 of 54) for follicular variant, and 50% (23 of 46) for follicular/solid variant of PTC. All cases (n = 36) involving lymph node metastases and 42 of 45 cases with extrathyroid invasion expressed galectin‐3. However, among the galectin‐3–positive cases (n = 169), 133 were without lymph node metastases, and 127 were without extrathyroid invasion. Galectin‐3 expression was not related to the size of intrathyroid PTC. Conclusions. Galectin‐3 immunohistochemical expression itself is not an indicator of local metastatic spread or extrathyroid invasion of PTC, thus being irrelevant clinically from this aspect. Galectin‐3 is an excellent marker for classical PTC but must be used with caution in diagnosing unconventional variants of PTC because of the possibility of false‐negative results. © 2005 Wiley Periodicals, Inc. Head Neck 27: XXX–XXX, 2005