Lectins in the vulva: II. Vulvar intraepithelial neoplasia and squamous cell carcinoma

This study used lectins as histologic probes to determine the cell surface oligosaccharide expression in different grades and types of vulvar intraepithelial neoplasia (VIN). Lectin binding patterns in metastasizing and non-metastasizing squamous cell carcinomas (SCCs) of the vulva were also compared to correlate lectin binding patterns with metastatic potential and other clinical/tumor characteristics. Twenty cases each of VIN epithelium, metastasizing SCC, and non-metastasizing vulvar carcinoma were randomly chosen from the pathology archives. Sixteen lectins were used to probe individual terminal oligosaccharide residues in formalin-fixed, paraffin-embedded tissue specimens from these cases through an indirect immunohistochemical technique. There were no differences in lectin binding patterns between the different histologic subtypes of VIN. In addition, there were no consistent differences between metastasizing and non-metastasizing primary tumors and no major differences in staining patterns between nodal metastases and the corresponding primary tumors. Furthermore, there was no identifiable correlation between lectin binding patterns and subsequent survival or local or regional recurrence; however, lectin staining of invasive tumor cells did appear to be related to local invasiveness. In addition, positive PNA binding was found to be a constant finding in each of the VIN and invasive SCC cases, confirming that the T-antigen becomes unmasked during the process of vulvar carcinogenesis. However, poorly-differentiated areas consistently showed absent lectin binding, suggesting loss of specific glycosyl transferase activities. In addition, the blood group "A" antigen appears to be lost during the process of tumorgenesis, although the blood group "O" antigen appears to be preserved.