This naevus is a form of dermal melanocytosis and was first described by the Japanese dermatologist Ota in 1939. It is usually congenital (not necessarily present at birth) but may appear in the second decade. Melanocytes are dispersed in a ribbon-like pattern between the collagen fibres and around the neurovascular bundles of the dermis. They run parallel to the skin surface and contain very fine granules of melanin. There is no disturbance of the pattern of collagen and elastic fibres. Melanophages are not found. The colour is variable, but is usually either slate-brown or blue. Naevus of Ota carries an increased risk of glaucoma and patients need to be referred for ophthalmic examination and long-term review. It is usually unilateral; it is bilateral as shown here in 5%. The distribution is usually restricted to the ophthalmic and maxillary divisions of the trigeminal nerve, but rarely patches may occur on the trunk as shown here. Occasionally, the pigmentation is confined to the eye with no cutaneous involvement. In very rare instances malignant melanoma has developed in naevus of Ota involving the skin or elsewhere. Ipsilateral sensorineural deafness is a rare event. Two acquired dermal melanocytoses that appear in adult life, often in the distribution of the nevus of Ota have been described. Hori’s naevus refers to bilateral nevus of Ota-like macules usually on the malar regions, while Sun’s naevus is acquired unilateral naevus of Ota. Cosmetic camouflage is useful and laser therapy may be of value but some patients repigment after treatment while others might develop posttreatment hypopigmentation. Some have tried dermabrasion and cryotherapy.
This page was last updated in May 2014.