Investigating the Safety and Efficacy of the 1927-nm Thulium Laser in Keratosis Pilaris

The investigators will use the LaseMD LEO Laser System (1927-nm Thulium laser) to create controlled, localized microscopic treatment zones (MTZs) of thermal injury to treatment area (unilateral upper arm). The investigators will utilize the random mode using the C1 tip (spot size 200 micrometers), which involves irradiation of the entire upper arm until diffuse erythema and edema appear. Additionally, the investigators may use the C5 tip (350 micrometers spot size) for focused treatment, up to five passes, until coagulation becomes evident. The maximum fluence for all C1 tip is 3-60 J/cm2 and 1-20 J/cm2 for C5 tips. The maximum pulse energy is 20 J with a pulse duration of 20 ms.