INTRODUCTION Also known as nevus of Ota or nevus fuscocaeruleus ophthalmomaxillaris, this lesion arises from dermal melanocytes. It typically affects tissues along the distribution of the trigeminal nerve and can affect superficial and deep tissues. This lesion is usually congenital, but later onset in puberty or during pregnancy has been reported. Women, especially Asian or black, are most commonly affected. Malignant degeneration may occur, particularly in whites, with the intraocular choroidal tissue being the most common site of involvement. Isolated ocular involvement without skin discoloration may occur and is termed ocular melanocytosis (melanosis oculi).
CLINICAL PRESENTATION The lesion appears as a flat blue-to-purple mottled pigmentation of the skin. It tends to follow the distribution of the ophthalmic and maxillary divisions of the trigeminal nerve. It is associated with ipsilateral ocular melanocytosis that can variously involve the conjunctiva, sclera, and uveal tract. Other ipsilateral involved tissues may be orbital fat and muscles, bone, periorbita, dura, and brain. The nevus tends to be unilateral, but bilateral involvement may occur. Pigmentation is irregular and may occur in small isolated disconnected patches. It may be so pale as to be overlooked on casual observation. Glaucoma can be an associated finding. Intraocular nevi, choroidal malignant melanoma, and orbital melanoma may occur.
HISTOPATHOLOGY Heavily-pigmented melanocytes in the upper and mid-dermis characterize oculodermal melanocytosis. The melanocytes are spindle-shaped, bipolar, or dendritic, and they tend to be oriented parallel to the skin surface but may also surround epidermal appendages. The epidermis may also be hyperpigmented.
DIFFERENTIAL DIAGNOSIS The differential diagnosis includes lentigo, malasma, malignant melanoma, osteogenesis imperfecta, ochronosis, and blue nevus.
TREATMENT Camouflage make-up may mask the lesion when limited and pale in color. Intense pulsed light therapy or pulsed dye lasers may diminish the degree of pigmentation. Periodic dilated fundus examination is important to rule out uveal melanoma.
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