Nevus of Ito is a rare dermal melanocytic nevus that is predominantly observed in Asian and darker skinned races. The nevus appears as a blue-hued patch and occurs within the distribution of the posterior supraclavicular and lateral cutaneous brachial nerves.

M. Ito first described a congenital pigmented patch or nevus fuscoceruleus acromiodeltoideus in 1954.1 Nevus of Ito is a slate blue patch of dermal pigmentation involving the distribution of the posterior supraclavicular and lateral brachial cutaneous nerves.1 While Ito's description is one of a congenital dermal melanocytosis (CDM), there have also been reports of acquired dermal melanocytosis (ADM) in the circumscribed area. Some authors have chosen to describe these lesions as acquired or late-onset nevus of Ito.2,3,4,5 Other literature has suggested that the dermal melanocytes of ADM lesions exist from birth.6,7,8,9 While the acquired cases of nevus of Ito have been included in our summary of the literature, our discussion later will focus on the reported congenital cases.

Case Report
A 51 year-old male of Chinese descent presented with an asymptomatic blue patch on his distal right arm (Figure 1, next page). The lesion had been present since birth. There was no contributory family history. On examination, a slate-blue pigmented patch was present at the right elbow and measured 6.5cm in diameter. General examination showed no similar facial or shoulder pigmented patches, nor any other abnormalities. Histopathological examination of the lesions showed dermal proliferation of dendritic melanocytes scattered in the upper portion of the dermis (Figure 2). There was no junctional proliferation of melanocytes, maturing nests of melanocytes, heavy pigmented dermal spindled melanocytes, nor any melanophages within sclerotic collagen.

Identification and Diagnosis
In 1961, seven years after Ito's description of the nevus fuscoceruleus acromiodeltoideus,1 four descriptions of possible nevus of Ito appeared in Mishima and Mevorah's review10 of American and European literature on nevus of Ota and nevus of Ito. Two of these reviewed cases pre-dated Ito's publication, however, we do not concur with one, as it did not fit the neurologic distribution.11 The other case, from a 1926 Italian publication, lacked both English translation as well as photographic evidence.12 The review's third case, from 1954, was consistent with an ADM.13 The last case, reported here, was consistent with a nevus of Ito and is included in our discussion.

Nevus of Ito is predominant in Asian and darker-skinned races and may be associated with an ipsilateral or bilateral nevus of Ota.14 Differential diagnosis includes pigmented macular ADM, acquired patch or plaque blue nevus, a nevus spilus that develops blue nevi, an aberrant Mongolian spot, melanoma metastasis, ecchymoses, vascular malformations, and a fixed drug eruption.15 Common blue nevi are usually less than 1cm and well circumscribed macules or papules. The blue-gray pigmentation seen on exam is due to the commonly known Tyndall effect, in which blue light is scattered as it passes through the dense dermis. History and physical exam help one differentiate amongst most of these conditions.

Histopathology of Nevus of Ito and Ota are identical, showing pigmented, spindle-shaped, bipolar or dendritic melanocytes within the upper and mid dermis.16 Pathology shows melanocytes that are generally more numerous and more superficially located than in the Mongolian spot.17 The melanocytes have an extracellular sheath composed of fine filaments and granules and are more developed than what is detected in melanocytes of the Mongolian spot.17 Hyperpigmentation of the basal layer and an increase in basilar melanocytes may occur, but there is no increased activity.16

While clinical presentation of the nevus of Ito commonly involves the shoulder, side of the neck and supraclavicular areas, our case involved the distal inferior branch of the lateral brachial cutaneous nerve with appearance at the elbow. No other case involving solely this distal location is reported in the literature. Of the twelve congenital cases in our summary (Table 1), gender break-down includes seven males (58 percent) and five females (42 percent). In comparison, this is a significantly lower percentage of female gender predominance associated with nevus of Ota (80 percent).14 However, the female predominance in cases of nevus of Ota may actually reflect a higher incidence of cosmetic complaints in this population.

Color variation is also a common observation in our findings. Excluding two cases for lack of information, color variations of nevi of Ito include blue, grey, slate, and brown as well as a spectrum of other dermatologic findings to include intralesional flecks, freckles, macules, and sweat and sensation changes. In half (50 percent) of the cases of Ito, a nevus of Ota was present. Both of these types of nevi may become more intensely pigmented following puberty. Spontaneous regression has not been described for the nevus of Ito.

Management
The Q-switched ruby (694nm) and alexandrite (755nm) lasers have been employed in the past to lighten dermal melanocytic lesions, particularly the Nevus of Ota.18,19 Most recently, the Nd:YAG (1064nm) was used to lighten a Nevus of Ota with favorable results.20 Cosmetic camouflage is an alternative option. Past therapies have included dermabrasion, chemical peels, electrodessication, topical bleaching protocols, dry ice, and CO2 (10,600nm) vaporization.19,20 However, these therapies risk depigmentation and scarring. Our patient opted for no cosmetic treatment. Any changes in pigmentation should be evaluated for development of melanoma arising within the lesion.24

The authors report no conflicts of interest. The opinions expressed in this article are those of the authors and do not represent the viewpoints of the United States Air Force, the United States Army, or the Department of Defense.