Nevus of Ota is a dermal melanocytic hamartoma that is unilaterally distributed along the first and second branches of the trigeminal nerve. It presents clinically as a bluish gray hyperpigmentation of the skin.
Nevus of Ito is a similar melanocytic condition, but the distribution is along the shoulder.
It is felt that these melanocytic disorders represent melanocytes that did not migrate completely from the neural crest to the epidermis during the embryonic period.
Nevi of Ito and Ota occur more frequently in skin of color populations from Asia and are rare in Caucasians.
Oculodermal melanosis was first described by Hulke in 1861.1 The entity nevus of Ota became known after it was described by Ota in 1939 as a bluish gray hyperpigmentation along the first and second divisions of the trigeminal nerve with occasional mucosal involvement2 [Figures 54-1 and 54-2]. Nevus of Ito, described by Ito in 1954, is a similar melanocytic condition, but the distribution is along the shoulder3 [Figure 54-3].
Nevus of Ota on the right forehead of an African American woman with Fitzpatrick type V skin.
Nevus of Oto with (A) infraorbital hyperpigmentation and (B) scleral hyperpigmentation.
Nevus of Ito with hyperpigmentation along (A) the left shoulder and (B) the upper back.
The etiology of nevi of Ota and Ito is unknown. It is possible that these melanocytic disorders represent melanocytes that did not migrate completely from the neural crest to the epidermis during the embryonic period.4,5 It is also possible that hormones play a role in the development of a nevus of Ota because the two peaks of onset are at infancy and puberty, which account for 61.35% and 21.99% of patients, respectively. Other factors, such as ultraviolet light, infection, and trauma, also may play a role.6,7
Nevi of Ota and Ito occur more frequently in skin of color populations of Asian descent and are rare in Caucasians. Some studies have shown the incidence to be from 0.014% to 1.1%.8,9 Nevus of Ota is more prevalent in women, with the male-to-female ratio being 1:4.8 to 5.68;6 the ratio for nevus of Ito is unknown. Most patients with nevi of Ota or Ito do not have a family history of this condition.
CLINICAL AND HISTOLOGIC MANIFESTATIONS
Nevus of Ota is considered to be a dermal melanocytic hamartoma ...