Galectin-1 is a useful marker for detecting neoplastic squamous cells in oral cytology smears.

Cytologic diagnoses in the oral region are very difficult due to the small amount of cells in smears, which are also exposed to many stimulating factors and often show atypical changes. Galectin-1 (Gal1) is a β-galactoside binding protein that modulates tumor progression. Gal1 is very weakly expressed in normal cells, but is often overexpressed in neoplastic lesions. The aim of the present study was to determine whether it is possible to differentiate reactive changes from neoplastic changes in oral cytology smears based on the expression of Gal1. A total of 155 tissue biopsy specimens and 61 liquid-based cytology specimens were immunostained by an anti-Gal1 antibody, and Gal1 expression levels were subsequently evaluated. These samples consisted of oral squamous cell carcinomas, epithelial dysplasia, and oral mucosal diseases. The positive and negative expressions of Gal1 were examined in 37 specimens collected by scalpel and cytobrush biopsy. The sensitivity, specificity, and positive predictive value of Gal1 were also evaluated in smears. In tissue sections, the positive ratio of Gal1 in neoplastic lesions was high (72.3%). In cytology specimens, the positive ratio of Gal1 was higher in neoplastic lesions (79.0%) than in those negative for intraepithelial lesion or malignancy (22.2%). A correlation was found between immunocytochemical Gal1 expression and immunohistochemical Gal1 expression (P < .001). The sensitivity (75.0%), specificity (75.0%), and positive predictive value (91.3%) of Gal1 were also high in smears. In conclusion, Gal1 may be a useful marker for determining whether morphologic changes in cells are reactive or neoplastic.