Nevus of Ota is a dark blue single spot of irregular shape or a group of merging spots that are located in the area of the eye, cheek and upper jaw. As a rule, it is one-sided. Pigmentation can capture the membranes and sclera of the eye, the mucous membranes of the nose and pharynx. Nevus Ota refers to melanoma-threatening pigmented nevi, although cases of its malignancy are quite rare. Patients are recommended to follow up with a dermatologist. Surgical treatment is carried out when signs of malignancy of the nevus are detected.
Nevus Ota is named after the Japanese ophthalmologist who first described it in detail. Other names of nevus: oculocutaneous melanosis, oculodermal melanocytosis, phacomatosis Otato. Nevus Ota, like the Mongolian spot, occurs mainly in people of the Mongoloid race. Isolated cases of its occurrence have been noted in persons of the Negroid and Caucasian races.
Nevus Ota is a dark blue or black-cyanotic pigmentation of the skin of the temple, lower eyelid, zygomatic area, upper jaw and cheek. Most often it is localized on one side of the face, in rare cases it is bilateral. Pigmentation has a uniform color and can be in the form of a single spot or consist of several spots passing into each other. There are nevi with different intensity of staining, from slightly noticeable pigmentation to ugly bright blue.
Typical is the accompanying nevus Ota pigmentation of the iris, sclera and conjunctiva of the eye, which has a bluish or brown hue. In some clinical cases, there is a spread of pigmentation on the lip border, the mucous membrane of the palate, throat, larynx and even nose. Despite the fact that the localization of the nevus coincides with the innervation zone of the I and II branches of the trigeminal nerve and can spread to the structures of the eye, it is not accompanied by any neurological or visual disorders.
Ota nevus can be congenital, appears in early childhood or in puberty. Unlike the Mongolian spot, the nevus of Ota does not disappear with time, but remains for life. In rare cases, the Ota nevus may undergo malignant transformation with the development of skin melanoma. At the same time, as a rule, visible changes occur in the nevus area: darkening or lightening of its color, uneven color, redness at the border of the nevus, blurring of its contour, the appearance of bumps, cracks or erosions on its surface.
Diagnosis is carried out on the basis of a typical picture and localization of the nevus, its differentiation from the Mongolian spot, giant pigment nevus, melanoma. A cyascopy of the pigment formation, dermatoscopy, and, if necessary, a biopsy are performed. Histological examination reveals the presence of melanocytes in the deep layers of the dermis.
In most cases, Ota nevus is a cosmetic problem and requires constant use of concealers and makeup. Given the rare cases of malignancy of the nevus and the difficulty of removing it due to localization on the face, modern dermatology, as a rule, does not perform surgical treatment of the Ota nevus. Laser removal gives a good cosmetic effect. It is necessary to constantly monitor the patient with a dermatologist for early detection of signs of nevus degeneration into melanoma.
A change in color, a sharp increase in pigmentation or its ulceration, as a rule, indicate a malignant transformation (malignancy) of the nevus. In such cases, urgent surgical intervention and radiotherapy of the formation are required.