Cyclooxygenase-2 expression in actinic keratosis

Introduction
Actinic keratosis (AK) is a common age-associated dermatosis typical for skin with photo-ageing features. Actinic keratosis lesions transform into invasive squamous cell carcinoma, if left untreated, but inductive factors remain unknown. A role of prostaglandins in the neoplastic process has been postulated.

Aim
To evaluate the possible correlation between cyclooxygenase-2 (COX-2) antigen expression in the immunohistochemical reaction and the stage of AK using the keratinocytic intraepidermal neoplasia (KIN) classification, age, sex and skin phenotype.

Material and methods
Skin samples of AK were examined histopathologically using the KIN classification. Immunohistochemical analysis of COX-2 expression was conducted using a commercially available kit and Image Processing and Analysis in Java. The intensity was presented as the percentage of cells with a positive reaction.

Results
Out of the 94 subjects with AK (aged 51–93 years; mean: 76.51 ±9.64), 58 were female and 36 male. Phenotype 2 was found in 50 and phenotype 3 in 44 patients. Mean values of positive immunohistochemical reaction for COX-2 were 2.16 ±6.56% for women and 1.96 ±6.59% for men (2.47 ±6.61%), with no statistically significant difference. Mean values of anti-COX-2 antibody reaction were 2.30 ±6.82% in the KIN1 group and 2.48 ±7.01% in the KIN2 group, while no expression was found in all cases with KIN3. No statistically significant differences were found between the percentage of COX-2 positive cells in KIN1/KIN2.

Conclusions
No statistically significant correlations between the intensity of COX-2 reaction and AK stage were found. Cyclooxygenase-2 expression in AK is not affected by age, sex, or skin phenotype.