The ruby laser irradiation causes selectively damages of the cutaneous melanin granules, but the cutaneous histological changes after the irradiation has not been well described. We applied the ruby laser to an excised skin using TOSHIBA Model LRT-301A. in this study, histological examinations were carried out light and electron microscopically. The results revealed as follows; exposure of 9J/cm2: Vacuolated changes were seen on the cells with melanin pigment in the basal layer. 16J/cm2: The vacuolation of cells among the basal cells were observed as elongated and degenerated in shape, The ring-like degeneration showing a crater was seen at the site of incontinentia pigmenti histologica in dermal papilla. 25J/cm2): Diffuse degenerations were seen in the basal layer. Excoriation were most frequently seen at this energy radiated akin. 40J/cm2: Diffuse degenerations were also observed in epidermis and dermal papilla with subepidermal cleft. In patients with seborrheic keratosis, senile pigmentation, nevus pigmentosus and nevus Ohta treated using ruby laser, the almost similarly histological alterations were observed. The study demonstrated that in the therapeutic efficacy of ruby laser on the dermal pigment disorders, the high energy irradiation was not always necessary, because over dose of energy-irradiation was absorbed by epidermal melanin granules (epidermal trap) and the basement membrane was also damaged.
