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Characteristic findings on physical examination
Nevus of Ota usually presents between birth and 12 years of age as an area of macular blue-grey pigmentation. Lesions range in size from a few cm in diameter to lesions which can cover more than half of the face. It is usually seen unilaterally on the face overlying the distribution of the ophthalmic and maxillary branches of the trigeminal nerve (Figure 1). Pigment is also seen in the ipsilateral sclera in approximately 2/3 of cases. Pigmentation has been reportedly seen bilaterally in 5-13% of cases, and can also involve the skin of the eyelids. Approximately 60% of cases occur within the first year of life and the other 40% occur at puberty. Most lesions persist into adulthood, after slowly growing throughout childhood.
Expected results of diagnostic studies
Histology will show fusiform melanocytes in the dermis with melanin granules and melanophages. There are a greater number of melanocytes in the dermis of a nevus of Ota than in dermal melanocytosis. This suggests that a nevus of Ota is a hamartoma.
The differential diagnosis is much broader for those lesions of nevus of Ota that do not involve the sclera. In those cases presenting at birth, the lesion could be confused with a giant lentigo or a congenital melanocytic nevus. For lesions presenting at an older age, the differential diagnosis would have to be expanded to include postinflammatory hyperpigmentation as well as a fixed drug eruption. Once scleral pigmentation is noted, the differential is limited to nevus of Ota with or without malignant transformation, or with or without an associated syndrome. Associated syndromes include Sturge-Weber, Klippel-Trenaunay and Phakomatosis Pigmentovascularis.
Who is at Risk for Developing this Disease?
Nevus of Ota is most commonly seen in those individuals of Asian descent. It was noted in 0.4-0.8% of all Japanese dermatology patients. Eighty percent of reported cases have been seen in women; however, it is not clear if this represents a real demographic difference, or simply the fact that it is more common for women to present for evaluation of a cosmetically concerning skin lesion.
What is the Cause of this Disease?
Just as is the case with dermal melanocytosis, nevus of Ota is the result of failed migration of melanocytes from the neural crest to their normal location in the basal layer of the epidermis.
Systemic Implications and Complications
Glaucoma can be seen in up to 10% of patients with nevus of Ota with scleral involvement. Additionally 10 cases of melanoma have been reported in lesions of nevus of Ota, affecting both the involved skin as well as the involved eye.
Treatment options for nevus of Ota include cosmetic therapies to cover up the lesion versus destructive therapies. Distructive modalities that have been tried with varying degrees of success and side effects include cryotherapy, dermabrasion, and electrodessication, all of which can leave scarring and hypopigmentation. One trial reported good to excellent outcomes in 22 of 24 patients treated with combined dermabrasion and carbon dioxide cryotherapy. Additionally, both chemical peels and laser treatments have been reported to be effective in lightening these lesions. Several lasers have been used to treat lesions of nevus of Ota. These include the Q-switched ruby, the Q-switched ND:YAG and the Q-switched alexandrite lasers.
Optimal Therapeutic Approach for this Disease
The therapeutic ladder for nevus of Ota is determined based on the size and extent of pigmentation of each given lesion. For smaller more lightly pigmented lesions, simple cosmetic cover-ups may be very effective. For larger darker lesions, combined dermabrasion with carbon dioxide cryotherapy was shown to produce good to excellent outcomes in more than 90% of patients. If that combination therapy is not available, multiple different lasers have been shown to be effective, with the data strongest in favor of the Q-switched alexandrite laser.
In addition to the cosmetic therapies described above, patients with a nevus of Ota require follow-up by both a dermatologist and an ophthalmologist, since cases of both cutaneous melanoma and ocular melanoma have been reported in those two-thirds patients with scleral involvement. Yearly examinationss should be performed by both subspecialists, with any nodular cutaneous lesion being biopsied. Ocular pressures should be checked regularly as well to assess for glaucoma .
Unusual Clinical Scenarios to Consider in Patient Management
There are two main unusual clinical scenarios to keep in mind while following patients with nevus of Ota. The first and most important involves the rare incidence of malignant melanoma arising either in the areas of skin pigmentation or scleral pigmentation, as both have been reported. The other broader issue is the association of nevus of Ota with other syndromes, such as Sturge- Weber, Klippel Trenaunay, and phakomatosis pigmentovascularis. These syndromes must be kept in mind, and if present, appropriately followed by the dermatologist and other relevant specialists in ophthalmology, neurology, and orthopedic surgery.
What is the Evidence?
Patel , BC, Egan , CA, Lucius , RW. “Cutaneous malignant melanoma and oculoderma melanocytosis (Nevus of Ota): report of a case and review of the literature”. J Am Acad Dermatol . vol. 38. 1998. pp. 862(A case report and review of several cases of melanoma, including cases of ocular melanoma, seen in association with nevus of Ota, also known as oculoderma melanocytosis.)
Balmaceda , CM, Fetell , MR, O’Brien , JL. “Nevus of Ota and leptomeningeal melanocytic lesions”. Neurology . vol. 43. 1993. pp. 381(A case report of leptomeningeal melanocytosis seen in association with a nevus of Ota. Leptomeningeal melanocytosis can also be seen in assocation with large congenital nevi, especially those overlying the midline of the scalp.)
Chan , HH, Leung , RS, Ying , SY. “A retrospective analysis of the complications in the treatment of nevus of Ota with the Q-switched Alexandrite and Q-switched Nd:YAG lasers”. Dermatol Surg . vol. 26. 2000. pp. 1000-6. (A retrospective review comparing the efficacy of the Q-switched Alexandrite and Q-switched Nd:Yag lasers in the treament of Nevus of Ota.)
Chan , HH, Alam , M, Kono, , T. “Clinical application of lasers in Asians”. Dermatol Surg . vol. 28. 2002. pp. 556-63. (An excellent review article discussing the use of several different lasers used to treat pigmentary anomalies in individuals of Asian descent.)
Hosaka , Y, Onizuka , T, Ichinose. “Treatment of nevus of Ota by liquid nitrogen cryotherapy”. Plast Reconstr Surg . vol. 95. 1995. pp. 703(A case of nevus of Ota treated with liquid nitrogen cryotherapy used without either laser or dermabrasion.)
Hata , Y, Matsuka , K, Ito , O. “Treatment of nevus of Ota: combined skin abrasion and carbon dioxide snow method”. Plast Reconstr Surg. vol. 97. 1996. pp. 544(An interesting review of a novel treatment for nevus of Ota. This treatment showed good to excellent cosmetic outcomes in 90% of patients who were treated with the combination of dermabrasion and carbon dioxide cryotherapy.)
Kopf , AW, Bart , RS. “Malignant blue (Ota’s) nevus”. J Dermatol Surg Oncol . vol. 8. 1982. pp. 442-5. (A historic review of one of the approximately 10 cases of malignant melanoma arising in a nevus of Ota.)
Lu , Z, Fang , L, Jiao , S. “Treatment of 522 patients with Nevus of Ota with Q-switched Alexandrite laser”. Chin Med J (Engl). vol. 116. 2003. pp. 226-30. (A very large study reviewing the safety and efficacy of the Q-switched Alexandrite laser in the treatment of nevus of Ota.)
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