The role of immunohistochemistry expression of COX-2 in differentiating pigmented benign and malignant skin neoplasms

Skin cancer is one of the most common types of cancer and its annual mortality rate is increasing. The induction enzyme of cyclooxygenase COX-2 causes biosynthesis of prostaglandin and thromboxane during inflammation of the body. Increasing the expression of COX-2 has an important role in the development and progression of malignant epithelial cancers and other types of cancers. Considering the diagnostic status of the marker, this study aimed to evaluate the expression of COX-2 for diagnosis and differentiation of benign skin pigmented neoplastic lesions from malignant melanoma types.

In this diagnostic study, the immunohistochemistry of COX-2 maker in 82 paraffin blocks of pigmented benign and malignant skin neoplasms of patients (49 men; 33 women) and its association with clinicopathological features of the tumor was evaluated. Data were analyzed using chi-squared and t test in SPSS18. Significance level was set at less than 5%.

The findings showed that 20 patients (24.3%) had malignant melanoma and 13 had significant COX-2 (3+ High), while COX-2 marker was not detected in other benign and malignant pigmented skin neoplasms (p<0.001). A significant association was found between COX-2   marker and grade (p<0.001), but there was no significant correlation with other clinicopathological tumor criteria. Sensitivity, specificity, PPV and NPV value of the COX-2 marker were 65%, 100%, 89.9%, and 100%, respectively.

Because of the high level of COX-2 in malignant melanoma skin marker, it can be used to distinguish benign and malignant neoplastic lesions (SCC and BCC) from melanoma and to provide effective therapeutic strategies through specific COX-2 enzyme inhibitors.