Effect of Q-switched Alexandrite laser irradiation on epidermal melanocytes in treatment of Nevus of Ota.
OBJECTIVE
To investigate injury to epidermal melanocyte by Q-switched Alexandrite laser.


METHODS
Multiple 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.


RESULTS
Melanosomes 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.


CONCLUSIONS
Injury of melanosomes in epidermal melanocytes is reversible.
Lu
Zhong
Z
Department of Dermatology, Huashan Hospital, Medical College of Fudan University, Shanghai 200040, China. luzhongmd@citiz.net
Chen
Junpang
J
Wang
Xiasheng
X
Fang
Lihua
L
Jiao
Sheng
S
Huang
Wen
W
D000293:Adolescent; D000328:Adult; D001608:Beryllium / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D053685:Laser Therapy; D007834:Lasers / Q000009:adverse effects; D008544:Melanocytes / Q000528:radiation effects*; D008854:Microscopy, Electron; D009507:Nevus of Ota / Q000473:pathology / Q000532:radiotherapy* / Q000648:ultrastructure; D012878:Skin Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000648:ultrastructure
C112654:alexandrite; D001608:Beryllium