Topical Treatment of Actinic Keratosis and Metalloproteinase Expression: A Clinico-Pathological Retrospective Study

Abstract

Actinic keratosis is an intraepithelial proliferation of atypical keratinocytes that could progress into invasive squamous cell carcinoma. Most evidence suggests an important role of the dermal matrix metalloproteinases in the progression of atypical skin epithelial lesions. We evaluated the clinical efficacy of three different therapeutic modalities (a medical device containing 0.8% piroxicam cream and 50+ sunscreen, photodynamic therapy, and ingenol mebutate gel) to treat suspicious actinic keratoses, which were biopsied for histopathological examination and then analyzed for the expression of matrix metalloproteinases by immunohistochemistry. Clinical, dermoscopic, and reflectance confocal microscopy evaluations revealed a gradual decrease in all standard scores validated for actinic keratosis assessment at the end of the treatments. From a histopathological point of view, we documented the substantial restoration of normal skin architecture, while the immunohistochemical evaluation of matrix metalloproteinases showed a reduction in expression in the treated skin lesions compared to the baseline. As actinic keratoses are considered the precursors of squamous cell carcinoma, their treatment is crucial to prevent the development of a more aggressive disease. Our study monitored the evolution of actinic keratoses subjected to three different topical therapies, with the value of correlating clinical and histopathological findings. Moreover, as the matrix metalloproteinases are largely recognized factors involved in the pathogenesis and evolution of actinic keratosis to squamous cell carcinoma, the demonstration by immunohistochemistry of a reduction in their expression after the treatments adds new valuable concern to the field.