Abstract:

Two cases of nevus of Ota resistant to multiple sessions of Q-switched laser treatment are reported. Both of the patients were females, who developed beige or blue patches on the left side of the face （zygomatic region, cheek） several months after birth. No conjunctiva or sclera was involved. The lesions spread to the left retroauricular region and posterior neck during pregnancy in one patient. Histopathological examination of the lesions showed scattered melanocytes and melanophages in lower dermis and subcutaneous adipose tissue as well as apparent proliferation of collagen. Immunostaining for CD34 showed no abnormality in the distribution of vascular endothelial cells in these tissues. No obvious improvement was observed in either of the patient after more than 10 sessions （12 sessions in 1 case, and 13 sessions in the other case） of treatments with Q-switched alexandrite （755 nm） or Q-switched Nd:YAG laser （1064 nm）. The immediate response of lesions to laser irradiation was unusual. Purpura or errhysis was absent in the lesions after repetitive irradiation with high-energy laser, but both were visible in the adjacent normal skin even after irradiation with low-energy laser.

Key words: effect