OBJECTIVETo analyze clinical information and efficacy of 602 cases of nevus of Ota, and investigate the histopathology and ultrastructure on the melanocytes before and after Q-switched Alexandrite laser irradiation.

METHODSClinical information of 602 cases of nevus of Ota were collected by applying clinical records, checking photos, and inquiry to patients by letters and telephones. Ten cases of biopsies were observed by light microscopy and 6 cases by electron microscopy before and after laser irradiation.

RESULTSNevus of Ota included congenital and acquired cases. Skin lesions mainly occurred in adolescence for the acquired cases. The main colours of lesions were brown and blue. The most local lesions were zygomata, temporal regions, and lower eyelids. According to multiple regression, the more treatment times, the better results. The effective rate was 85.20% and 100% after 6 and 9 treatment times, respectively, while the cure rate was 55.72% and 98.46%, respectively. The eyelids involved and Tanino types influenced the treatment times by COX models analysis. Electron microscopy showed many melanosomes in the dermal melanocytes. After laser irradiation, the outlines of the dermal melanocytes were observed, the melanosomes were broken to dense and tiny granules.

CONCLUSIONSQ-switched Alexandrite laser is safe and effective for the treatment of nevus of Ota. The results of treatment are correlated with the area and size of the lesion. The dermal melanocytes in nevus of Ota can be selectively destroyed by Q-switched Alexandrite laser with less injury around tissues.

Adolescent ; Adult ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Infant, Newborn ; Laser Therapy ; Male ; Melanocytes ; ultrastructure ; Melanosomes ; radiation effects ; ultrastructure ; Nevus of Ota ; radiotherapy ; ultrastructure ; Skin ; ultrastructure ; Skin Neoplasms ; radiotherapy ; ultrastructure

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

Patients with vitiligo seem be less prone to the development of lentigines as a side effect of long-term photochemotherapy than do psoriatics. An 8-year-old boy who had a vitiliginous patch on his left thigh, had been receiving photochemotherapy since he was 2 years old. At the age of 3, multiple star-shaped brownish macules developed at the site of treatment. Photochemotherapy was continued until the patient was 6 year old, at which time no improvement in the vitiligo was seen, so photochemotherapy was discontinued. Now 2 years after treatment the lentigines still persist. On electron microscopic examination, the melanocytes showed two patterns of cell death: coagulative necrosis and apotosis together with atypical cytoplasmic and melanosomal alterations.
Case Report ; Child ; Human ; Lentigo/*etiology/pathology ; Male ; Melanocytes/ultrastructure ; Microscopy, Electron ; PUVA Therapy/*adverse effects ; Vitiligo/drug therapy