Ultrastructural evidence for thermal injury to pilosebaceous units during the treatment of acne using photopneumatic (PPX) therapy

Abstract

Background and objective: Acne is a very prevalent skin disorder, and several devices, such as blue light, pulsed dye laser, diode laser, LED, RF and pulsed light systems, have been reported to have varying degrees of efficacy for treatment. Photopneumatic therapy (PPX) is a novel technology that combines pneumatic energy with a broadband light source to manipulate the optical characteristics of the skin. A vacuum suction raises target structures in the dermis closer to the surface of the skin prior to exposure, allowing for more efficient energy transmission. This study tested the hypothesis that a combination of pulsed light and suction would affect sebaceous plugging within diseased pilosebaceous apparati at a histological level, resulting in the rapid clearance of acne lesions. Methods: Eight individuals were treated with PPX once per week for a total of five treatments. Punch biopsies of the treated areas were obtained just after the first exposure, just before the third exposure and immediately after the fifth exposure. Those specimens were examined by conventional and by electron microscopy for any alterations following treatment. Results: Immediately following the first treatment, the mechanical extrusion of comedo contents from the infundibulum was observed histologically. One week after the second treatment, thermally injured bacteria as well as direct thermal injury to pilosebaceous apparati were observed ultrastructurally. Conclusion: These results correlate with clinical reports on decreased sebaceous gland activity after PPX treatment and may mechanistically give rise to the rapid regression of acne lesions.