Cyclooxygenase-2 (COX-2) immunostaining does not correlate with the degree of vulvar neoplasia

The cyclooxygenase-2 (COX-2) enzyme is up-regulated in inflammatory and neoplastic conditions. In the last decade, its biological role has been investigated in various pre-invasive and invasive cancers with the hope that it can serve as a target for cancer prevention and treatment.

We evaluated the expression of COX-2 in vulvar biopsies to determine its relationship to the degree of dysplasia. COX-2 expression was studied by immunohistochemistry in 62 consecutive vulvar biopsies divided into four diagnostic groups. Group 1 included inflamed vulva (n = 14); group 2, vulvar intraepithelial neoplasia (VIN) I and VIN II (n = 20); group 3, VIN III and carcinoma in situ (n = 18); and group 4, invasive squamous cell carcinoma (n = 10). Representative sections were immunostained using polyclonal anti-COX-2 antibodies at concentration 1:25 without pretreatment. Immunostaining was scored according to the proportion of positive epithelial cells in the vulvar mucosa as 0 (no positive cells), 1(< 5% positive), 2 (6-50% positive), or 3 (> 50% positive).

Mean immunostaining scores were 1.6, 1.4, 0.7, and 1.2 for groups 1, 2, 3, and 4, respectively. Scores were different between the groups (chi(2) = 9.908, P = 0.019) as shown by Cochran-Mantel-Haenszel statistical analysis (modified ridit scores), but did not correlate with age or the degree of dysplasia. The strongest staining for COX-2 was in the inflammatory group.

COX-2 staining in inflamed, dysplastic, and malignant vulvar epithelium is variable but, as shown in this study, does not correlate with the degree of vulvar dysplasia or malignancy.