671 Morphological and histological effect of emollient application in actinic keratoses

Abstract

Evaluation of actinic keratosis (AK) treatment response is based primarily on clinical endpoints. Although inactive ingredients in topical therapeutics are assumed to be inert, effect on photodamaged (PD) human skin and existing AK lesions is largely unknown. The aim of this study is to assess histological, morphological, and clinical features of AKs and PD skin after daily emollient application to understand potential confounding effects of emollient vehicles. 24 patients were enrolled and randomized to either the emollient group (N=12) or control group (N=12). Patients in the emollient group applied twice daily VanicreamTM to study sites for 12 weeks. Three AKs and two areas of nearby PD skin were evaluated per patient. Sites were imaged by reflectance confocal microscopy (RCM), clinically evaluated, and biopsied for immunohistochemical evaluation. Expression of Ki67, a marker of cell proliferation, was significantly higher in AKs (35%, SD 10.2) compared to PD skin (20%, SD 11.4) at baseline. Caspase-14, a marker of differentiation, was significantly lower in AKs (26%, SD 14.9) compared to PD skin (61%, SD 13.7) at baseline. Baseline expression of p53 was not significantly different between AKs (34%, SD 17.3) and PD skin (32%, SD 18.2). There was no observed effect of emollient on biomarker expression over time in AKs or PD skin. However, there was a significant decrease in RCM-measured stratum corneum thickness in emollient treated AKs (-26μm, p=0.035), suggesting that emollient-treated lesions may appear less hyperkeratotic on exam. It is critical to determine emollient effect on AKs to control for potential confounders in clinical trials and to understand how inactive ingredients may modulate evaluation of AK response to treatment.