OBJECTIVETo evaluate the clinical response of Nevus of Ota to Q-switched Alexandrite laser, and analyze factors that influence the treatment outcome.

METHODSA total of 522 patients treated with Q-switched Alexandrite laser were included in the study. Single and multiple variate analyses of various factors were performed.

RESULTSSatisfactory result was observed in all patients, none of whom developed scarring. Clinical response was improved with additional treatment sessions. The clinical response of the 20 - 27-week treatment interval group was significantly better than that of the 12 - 19-week interval group, but showed no significant difference as compared with both the 28 - 35 and > or = 36-week interval group. Zygomatic, buccal and frontal areas showed better response than ocular and temporal areas. Treatment session, interval, and fluence were significant factors identified by multivariate analysis.

CONCLUSIONSQ-switched Alexandrite laser is an ideal method for treating Nevus of Ota without injury. The number of treatment sessions is more important than interval or fluence.

Adolescent ; Adult ; Child ; Child, Preschool ; Facial Neoplasms ; pathology ; surgery ; Female ; Humans ; Infant ; Laser Therapy ; adverse effects ; methods ; Male ; Middle Aged ; Nevus of Ota ; pathology ; surgery ; Pigmentation Disorders ; etiology ; Skin Neoplasms ; pathology ; surgery

OBJECTIVETo investigate injury to epidermal melanocyte by Q-switched Alexandrite laser.

METHODSMultiple biopsies were performed on 5 patients with nevus of Ota from before irradiation to 1 year after irradiation. Fourteen specimens were obtained for light microscopy, and 17 for transmission electron microscopy.

RESULTSMelanosomes in epidermal melanocytes were both smaller in size and fewer in number than those in dermal melanocytes. Immediately after irradiation, focal extracellular vacuoles of the basal layer could be observed under light microscopy. Most epidermal melanocytes underwent mild or moderate injury in the form of vacuolated melanosomes, swollen mitochondria, dilation of endoplasmic reticulum, and expansion of extracellular space, retaining intact cell membranes. Normal structures were restored 5 months to 1 year after irradiation, with no depigmentation or hyperpigmentation as seen by light microscopy.

CONCLUSIONInjury of melanosomes in epidermal melanocytes is reversible.

Adolescent ; Adult ; Beryllium ; therapeutic use ; Female ; Humans ; Laser Therapy ; Lasers ; adverse effects ; Melanocytes ; radiation effects ; Microscopy, Electron ; Nevus of Ota ; pathology ; radiotherapy ; ultrastructure ; Skin Neoplasms ; pathology ; radiotherapy ; ultrastructure