Nevus of Ito is similar to nevus of Ota from both a pathologic and pathophysiologic perspective. It differs mainly in its distribution. Nevus of Ito most commonly is seen overlying the distribution of the posterior supraclavicular and cutaneous brachii lateralis nerves. The lesions usually present at birth as blue-brown macules ranging from the upper chest to the shoulder and sometimes extending onto the upper arm. Additionally, there is an acquired variant seen in Asian women between aged 19-69.
Histology will show elongated dendritic melanocytes scattered among collagen bundles in the upper part of the reticular dermis. As is the case with nevus of Ota, these lesion are more cellular than are biopsies taken from lesions of dermal melanocytosis.
Similar to nevus of Ota, nevus of Ito is most commonly seen in individuals of Japanese descent, but it can also be seen in individuals of African and East Asian descent. Lesions may also be seen in association with nevus of Ota, but is thought to be overall much less common.
Similar to nevus of Ota and dermal melanocytosis, nevus of Ito results from a failed migration of melanocytes from the neural crest to the basal layer of the epidermis, leaving them in the reticular dermis.
There are no systemic implications or complications associated with nevus of Ito.
Since the histology is identical to nevus of Ota, the same types of therapies have been tried for nevus of Ito. These include a variety of different lasers with the Q-switched ruby laser considered to be the most effective by some authors. Overall, there are many fewer case reports on the treatment of nevus of Ito, mainly because its location arouses less cosmetic concern.
Reassuring the patient that this is only a lesion of only cosmetic concern is of paramount importance. Should treatment be desired, laser treatment, preferably with the Q-switched ruby laser, may be recommended.
Since nevus of Ito is benign, has no known systemic associations, and occurs in a nonworrisome location from a cosmetic perspective, no work-up, follow-up, or treatment is necessary. Although the development of a melanoma in a nevus of Ito is an extrarodinarily rare event, should any suspicious changes occur within the lesion, a biopsy should be performed.
To date, there have been two cases of melanoma associated with a nevus of Ito. Therefore, any suspicius clinical change in a nevus of Ito should be biopsied.