Cyclooxygenase (COX), also known as prostaglandin endoperoxide synthase, catalyzes the conversion of arachidonic acid to prostanoids. There are two different isoforms of COX, referred to as COX-1 and COX-2. Overexpression of COX-2 has been demonstrated in various neoplasms. In this study, we plan to utilize COX-2 in understanding the difference of squamous cell carcinoma and keratoacanthoma which have many similarities in both morphological and histological features. The objective of this study is to study the expression of COX-2 in squamous cell carcinoma and keratoacanthoma and to discuss its clinical significance. The expression of COX-2 in 55 cases of skin tumors (including 30 specimens of squamous cell carcinoma, 25 specimens of keratoacanthoma) and 20 normal skin tissues was detected by immunohistochemical technique. The positive expression of COX-2 was found in 73.3 % (22/30) of squamous cell carcinoma and 12 % (3/25) of keratoacanthoma cases. The positive expression rate of COX-2 in 55 skin tumors (45.5 %) was significantly higher than that in normal skin tissues (5 %) (χ (2) = 10.598 %, P < 0.05). The expression of COX-2 in squamous cell carcinoma (73.3 %) was significantly higher than that in keratoacanthoma (12 %) (χ (2) = 20.69, P < 0.05). COX-2 overexpression may play a potential role in the pathogenesis of skin tumors. The positive expression rate of COX-2 is associated with the malignant degree of the tumor, and also it may help differentiating squamous cell carcinoma from keratoacanthoma.
Keywords: Cyclooxygenase-2; Immunohistochemistry; Keratoacanthoma; Squamous cell carcinoma.