Nevi of Ota and Ito

Updated: Jun 02, 2016
  • Author: William A Berger; Chief Editor: Dirk M Elston, MD  more...
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Overview

Background

Nevus of Ota, which originally was described by Ota and Tanino in 1939, is a hamartoma of dermal melanocytes. Clinically, nevus of Ota presents as a blue or gray patch on the face, which is congenital, with onset at birth or around puberty and is within the distribution of the ophthalmic and maxillary branches of the trigeminal nerve. The nevus can be unilateral or bilateral, and, in addition to skin, it may involve ocular and oral mucosal surfaces. [1, 2]  See the images below.

Nevus of Ota. Courtesy of DermNet New Zealand (htt Nevus of Ota. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/lesions/ota2.jpg).
Nevus of Ota. Courtesy of DermNet New Zealand (htt Nevus of Ota. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/lesions/ota.jpg).

Nevus of Ito, initially described by Minor Ito [1, 2, 3] in 1954, is a dermal melanocytic condition affecting the shoulder area in the distribution of the posterior supraclavicular and lateral cutaneous brachial nerves. Nevus of Ito often occurs in association with nevus of Ota in the same patient but is much less common, although the true incidence is unknown. See the image below.

Nevus of Ito. Courtesy of DermNet New Zealand (htt Nevus of Ito. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/lesions/melanocytosis-ito.jpg).

Additionally, the Medscape article Melanocytic Nevi may be of interest.

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Pathophysiology

The etiology and pathogenesis of nevi of Ota and Ito are not known. Although unconfirmed, nevus of Ota and other dermal melanocytic disorders, such as nevus of Ito, blue nevus, and Mongolian spots, may represent melanocytes that have not migrated completely from the neural crest to the epidermis during the embryonic stage. [4] The variable prevalence among different populations suggests genetic influences, although familial cases of nevus of Ota are exceedingly rare. The two peak ages of onset in early infancy and in early adolescence suggest that hormones are a factor in the development of these conditions. Schwann cell precursors have been shown to be a source of melanocytes in skin. [5] The observation of dermal melanocytes in close proximity with peripheral nerve bundles in nevus of Ito suggests that the nervous system is a factor in the development of nevus of Ito, although the true pathogenesis remains unknown.

A new theory is emerging regarding the pathogenesis of nevi of Ota and Ito. It has been demonstrated that most nevi and melanomas are associated with mutations in the BRAF and NRAS genes of the MAP kinase pathway. [6, 7] However, blue nevi and nevi of Ota and Ito do not possess these mutations. Instead, it has been discovered that the melanocytes present in these lesions often contain a mutation in a G-coupled protein gene, GNAQ. This mutation causes the G-coupled protein to be constitutively turned on, resulting in increases in the melanoblast pool. These melanoblasts then migrate during embryogenesis to the skin, the uvea, and/or the meninges, creating the various manifestations of Nevus of Ota. [8, 9, 10] This would explain the association between nevus of Ota and uveal and leptomeningeal melanocytosies. GNAQ mutations have also been shown to underlie other cutaneous disorders, including phakomatosis pigmentovascularis (of which melanocytosis may be a feature), [11] nevus flammeus, [12] and Sturge-Weber syndrome.

It has also been shown that the risk of developing cutaneous, uveal, or leptomeningeal melanomas in the setting of lesions such as nevus of Ota is related to monosomy of chromosome 3. The tumor suppressor gene BAP1 (BRCA-associated protein 1) is located on this chromosome. Loss of one the BAP1 allele is linked with an adverse prognosis. Monosomy 3, coupled with loss of 1q or gain of 8q, is associated with a worse outcome. Evaluation for this abnormality in melanomas associated with nevus of Ota could aid in prognosis, treatment, and follow-up. [13]

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Epidemiology

Race

Nevi of Ota and Ito occur most frequently in Asian populations, with an estimated prevalence of 0.2-0.6% for nevus of Ota in Japanese persons. Nevus of Ito is less common than nevus of Ota, although the true incidence is unknown.

Other ethnic groups with increased prevalence include Africans, African Americans, and East Indians.

Nevi of Ota and Ito are uncommon in whites.

Sex

The male-to-female ratio is 1:4.8 for nevus of Ota. [14] The ratio for nevus of Ito is unknown.

Age

The first peak of onset of nevus of Ota occurs in infancy, with as many as 50% of nevus of Ota cases present at birth. The onset for nevus of Ito is at birth or shortly thereafter.

The second peak of onset for nevus of Ota is seen during adolescence.

Isolated cases of delayed-onset nevi of Ota that first appear in adults, including in older patients, have been reported. [15] The same has rarely been found in patients with nevus of Ito. [16]

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Prognosis

Without treatment, the skin lesions are permanent.

Nevus of Ota can cause facial disfigurement, resulting in emotional and psychologic distress. [17] In rare cases, melanoma, which can be life threatening, has been reported to arise from nevus of Ota. [18]  Glaucoma also has been associated with nevus of Ota.

Nevus of Ito usually does not have symptoms and causes little cosmetic concern to the patients; sensory changes occasionally are present in the lesion. Rarely, nevus of Ito has progressed to cutaneous melanoma. [18, 19]

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Patient Education

Make patients aware of the risk associated with the development of glaucoma. Instruct patients to schedule periodic follow-up visits with an ophthalmologist.

Instruct patients to report any unusual symptoms or changes to the lesional areas to a physician, since a small risk for malignant degeneration exists.

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