Immunohistochemical study of COX-2 in melanocytic skin lesions

Abstract

Background: cyclooxygenase-2 (cox-2) is involved in pathogenesis of various tumors and possibly malignant skin tumors including malignant melanoma; however, there is not enough information about cox-2 expression in benign melanocytic lesions. In the present study we compared the expression levels of cox-2 in malignant melanoma and benign melanocytic lesions. Methods: In this analytical study, 42 malignant melanoma from all 4 subtypes and 38 benign melanocytic lesions including dysplastic nevus, Spitz nevus and atypical nevus were evaluated for cox-2 expression using immunohistochemistry staining and intensity of cell staining (quantitatively and qualitatively). Results: Malignant melanoma compared to benign melanocytic lesions had significantly higher levels of staining (p<0.001), and much more intense coloration (p<0.001) and higher overall staining score (p<0.001). Regarding the cox-2 staining between malignant melanoma subtypes, all four subtypes mostly had staining intensity over 60%. Also in terms of quality, the most intense staining was in the ALM, and LM and NM had moderate staining intensity. With increasing depth of involvement, cox-2 staining increases. Intensity of cell staining was also higher in cases with tumor depth of 2-4 mm. Conclusion: The results indicate the effectiveness of cox-2 in differentiating between malignant melanoma and benign melanocytic lesions. cox-2 expression correlated with the depth of invasion. Although cox-2 alone cannot be used to differentiate melanoma from benign lesions, it can be helpful in combination with other methods, in determining the prognosis and future targeted therapies.