Effect of 27-MHz radiofrequency on hair follicles: histological evaluation of skin treated ex vivo.

Background: A multitude of methods and treatments exist for cosmetic hair removal. Electroepilation is a commonly performed method of hair removal that is so-called "permanent"; however, there is a paucity of histological studies of the effects of radiofrequency (RF) on hair follicles.

Objective: This study aimed to observe the destruction of human hair follicles and surrounding tissue after the treatment with 27.12-MHz RF, with more attention paid to the thermal destruction of bulge and bulb/dermal papilla.

Methods: Human scalp specimens obtained during face-lift surgery were treated with 27.12-MHz RF. The probe tip was inserted into hair follicle, RF current was applied, and treated specimens were processed for histological analysis.

Results: Significant damages were observed on treated hair follicles. Thermal damage was lance-shaped and extended over several hundred micrometers (100-400 μm). The location of destruction areas varied, likely depending on the point of insertion of the probe. The epidermis remained intact.

Conclusion: This study shows that the general mechanism of thermolysis is to generate damage to cells and tissues surrounding the insertion point of the filament. The results suggest that if the insertion point is close to the bulge region, there is a risk to destroy hair follicle epithelial stem cells.