dermacare - NEVOS OF OTA

Bilateral nevus of Ota in a light-skinned woman

Abstract

Nevus of Ota is a dermal melanocytosis, clinically localized on skin that is innervated by the first and second branches of the trigeminal nerve. It occurs almost entirely in Asian people. This manifestation is rarely described in light-skinned non-Asian persons. We present a case of bilateral Ota nevus in a 47-year-old light-skinned non-Asian woman.

Clinical synopsis

A 47-year-old light-skinned non-Asian woman presented with bilateral manifestations of nevus of Ota. The ocular hyperpigmentation was present at birth and the skin lesions appeared in early childhood. Clinically, flat blue-gray pigmentation with an irregular border was present on the skin of the lateral ocular areas. Bilaterally, the sclerae were also involved. Nasal and oral mucosa were not affected. Ophthalmologic examination showed no abnormalities. Audiometric examination was within normal limits.

Comments

Nevus of Ota was first described by a Japanese dermatologist, M.T. Ota, in 1939 . Histopathology of affected skin shows the presence of dendritic cells containing melanin in the dermis . Ota nevus can be congenital or acquired in adolescence. It occurs almost entirely in persons of Asian descent. Manifestations in fair-skinned non-Asians are very rare . The clinical manifestations are usually unilateral; only 5 percent of cases are bilateral. Clinically, blue-gray macular pigmentation with irregular border involves skin that is innervated by the first and second branches of the trigeminal nerve. Extrancutaneous manifestations include ocular involvement of sclera, episclera, conjunctiva, cornea, retina, and uveal tract. Similar discoloration can be observed in oral mucosa (buccal and palatal), as well as in nasal mucosa and the tympanic membrane. Leptomeninges can also be affected. The occurrence of melanoma has been rarely described .

Various therapies have been used successfully. Cosmetic coverup products can be used for camouflage. Cryosurgery and microsurgical treatments can leave disfiguring scars and are not recommended. Chemical bleaching agents can damage epidermal melanocytes and provoke permanent hypopigmentation or depigmentation . Combined dermabrasion and the carbon dioxide snow method has produced good results .

In recent years the use of laser therapy has been very effective and gives new hope for patients with nevus of Ota . Various lasers are used in treatment of pigmentary disorders and the best results for treatment of this condition appears to be obtained with Q-switched Nd-YAG, ruby and alexandrite lasers. The long wavelengths penetrate deeply into the dermis and provoke selective photothermal and photomechanical destruction of dermal melanocytes . After irradiation, the shape of dermal melanocytes and their melanosomes is changed. Melanosomes are fragmented into smaller pieces and their cell membranes are disrupted; the nucleus is fragmented or destroyed. Destruction of dermal melanocytes can be achieved without collateral injury to the surrounding tissue . There is no significant epidermal pigmentation in patients with nevus of Ota. Melanosomes in epidermal melanocytes are different compared to dermal melanocytes; they are smaller and more numerous. After laser therapy epidermal melanocytes are reversibly changed; light microscopy shows expansion of extracellular space, swollen mitochondria, dilatation of endoplasmic reticulum, and vacuolated melanosomes. One year after the treatment normal cell structure is completely restored .

Complications such as mild purpura, erythema and edema can follow the treatment and improves after a few days. The most frequent complication is hypopigmentation, which can be transient or permanent. Hyperpigmentation can also occur 2-3 weeks after treatment and lasts for a few months. Topical tretinoin gel, hydroquinone, and corticosteroid creams can be used in the treatment of post-inflammatory hyperpigmentation . Laser therapy is very effective in the treatment of nevus of Ota, and recurrence is rare .