1.What is Nevus of Ota? Nevus of Ota was first described by Ota in 1939, so it is called nevus of Ota. It is mainly manifested as unilateral or bilateral blue-brown patches on the face and is common among Asians and blacks. Because it is a blue-gray birthmark occurring in the area innervated by the trigeminal nerve, it is also called a brownish-gray nevus on the palate of the eye. 2.How does nevus of Ota occur? The blue and blue-gray color in nevus of Ota is due to melanin production by melanocytes in the dermis. It is caused by the fact that during embryonic development, some melanocytes fall out of line during the migration of melanocytes from the neural crest to the epidermis at around 11 weeks. Since the incidence of the disease is significantly higher in women than in men, it is believed that the hormone level in female patients plays a role in the occurrence of the disease. 3.What is the manifestation of nevus of Ota? Nevus of Ota usually occurs unilaterally on the upper and lower eyelids, cheekbones, and temporal areas of the face, but occasionally there are bilateral nevus of Ota, but it is rare. 2/3 of patients have ipsilateral scleral involvement, which is a typical feature of nevus of Ota, and vision is mostly unaffected. The rash usually consists of pinpoint to several millimeter sized spots fused together. Individual spots may be round, oval or irregular in shape and may be light tan, gray, cyanotic, purple or black in color. It appears in 50% of patients after birth, and in half of them it appears only at the age of about 10. 4.What are the effects of nevus of Ota? Will it become malignant? Nevus of Ota has a great impact on the appearance and psychology of patients. However, it is rarely malignant, and among the reports of malignant change, most of them are Caucasian. When nevus of Ota accumulates in the eye, cases have been reported to develop into primary melanoma of the choroid, orbit, iris, optic cross and meninges. Since most associated malignant melanomas mostly originate in the eye, nevus of Ota involving the eye needs to be closely monitored and must be biopsied when new subcutaneous nodules appear. 5.How is nevus of Ota treated? Oral and topical drugs have no therapeutic effect. The best method is laser treatment (Q-switched ruby laser, Q-switched emerald laser, Q-switched Nd-YAG laser), and the treatment interval is usually 2-3 months, and the next treatment should be carried out after the pigmentation subsides. Laser treatment is still effective in recurrent cases. Use with caution for scarring. In general, most of the nevus of Ota can be removed by cosmetic laser treatment and achieve better cosmetic results.