Naevus of Ota

Naevus of Ota is a colored skin marking of slate-brown or blue/grey coloring. It is an unusual birthmark in which the melanocytes (pigment cells) are found deeper than normal (in the dermis instead of the epidermis). This is also known as dermal melanocytosis.

It is not known why these naevus occur. Specific mutations have been detected within the dermal melanocytes.

Naevus of Ota is common and is present at birth in 50% of cases but may appear during adolescence or adult life. Thus, researchers suggest hormones play a part in their development.

Treatment of a naevus of Ota is usually cosmetic camouflage to cover the disfiguring markings. Laser treatment (usually using 1064nm Q switched Nd: YAG or QaS ruby laser) and intense pulsed light (IPL) work by destroying the dermal melanocytes. Multiple treatments are necessary, often with a combination of devices. Laser treatment is more effective in light-skinned individuals than in those with dark skin. Unfortunately, recurrence is common after clearance, sometimes resulting in a darker hue.

If the eye is affected, arrange for a regular eye examination to detect glaucoma. You should see a dermatologist if there is any change in the naevus, especially if you are fair-skinned.

• Hyperpigmentation usually located on one side of the face (unilateral) but can be on both sides (bilateral)
• Color may vary to include brown-violet, violet-blue or blue-green hues
• Hyperpigmentation of parts of the eye may occur sclera, cornea, iris, retina
• May also involve the inside of the mouth
• Naevi present in childhood may also grow and darken until adulthood is reached
• Color or perceived color of naevi may change according to personal and environmental conditions, e.g. fatigue, menstruation, hot weather
• If affecting the eye, it rarely causes glaucoma
• Malignant Melanoma very rarely develops within dermal melanocytosis and has usually been reported in Caucasians. Ocular melanoma has been reported in the choroid, brain, orbit, iris, ciliary body, and optic nerve in association with a nevus of Ota.