Nevus Of Ota And Nevus Of Ito
Both nevus of Ota (oculodermal melanocytosis, nevus fuscoceruleus ophthalmomaxillaris) and nevus of Ito (nevus fuscoceruleus acromiodeltoideus) are considered to be benign hamartomatous overgrowths of melanocytes. These two processes are located on the face and upper shoulder, respectively. They share a common pathogenesis and histology with Mongolian spots and are most likely caused by abnormal embryological migration of melanocytes.
Clinical Findings: The diagnosis of these conditions is most often made on clinical grounds, and a skin biopsy is rarely, if ever, needed to make the diagnosis. Nevus of Ota and nevus of Ito have characteristic locations, and this helps the clinician make the ultimate diagnosis. The closely related Mongolian spot is located on the lower back of infants and manifests as a deep blue, asymptomatic macule that almost always fades away slowly until it disappears completely by adult-hood. It has a higher prevalence in children of Asian or Mayan Indian descent.
Nevus of Ota occurs in a periocular location and can affect the bulbar conjunctiva. It is almost always unilateral in nature. Nevus of Ota manifests as a bluish to blue-gray macule with indistinct borders that fade into the surrounding normal-colored skin. It is usually located over the distribution of the first two branches of the trigeminal nerve. If the bulbar conjunctiva is involved, the color may vary from bluish gray to dark brown. This condition occurs much more commonly in women and in patients of Asian descent. Nevus of Ota is most often seen in isolation, but on occasion it can be seen with a coexisting nevus of Ito.
Nevus of Ito has a similar clinical appearance; however, the location is on the shoulder girdle and neck. Unilateral lesions are the rule. The blue to bluegray macules can be large and can cause the patient considerable dismay. These lesions are asymptomatic but can be a major cosmetic concern for patients and can cause considerable psychological and social difficulties.
Both nevus of Ota and nevus of Ito are more preva- lent in the Asian population. Nevus of Ota appears to have a very small malignant potential. It is believed that Caucasian females with a nevus of Ota are at higher risk for transformation into malignant melanoma. Nevus of Ito does not appear to have a malignant potential.
Histology: The histological findings in nevus of Ota, nevus of Ito, and Mongolian spots are identical and resemble those of common blue nevi. Within the lesion, nodular collections of melanocytes are found in the dermis, with noticeable elongation of the melanocytes in the superficial dermis. There is surrounding fibrosis in the dermis with a number of melanophages present.
Pathogenesis: Under normal circumstances, melano- cytes migrate during embryogenesis from the neural crest outward to their final locations (e.g., skin, retina). Nevus of Ota and nevus of Ito are believed to be caused by abnormal migration of these melanocytes. During their migration, some unknown signal causes the melanocytes to collect on the face or on the shoulder, respectively. There does not appear to be a genetic inheritance pattern.
Treatment: These are benign lesions that require no therapy. It is not unreasonable to monitor them clinically for the rare development of malignant transformation. Most patients present for therapy because they are bothered by the appearance of the lesions.
Because of the psychological and social hardships engendered by these cosmetically disfiguring lesions, therapy is appropriate, albeit difficult. If only small areas are involved, cosmetic makeup may be used to camouflage the region. Topical therapies with hydroquinone and tretinoin have shown minimal to no effect on the pigmentation.
Use of the 1064-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser has resulted in the most success in treating these lesions, and it can be used in patients of almost any skin type. Q-switching of the laser is a method that has been shown to increase its efficacy. Q-switched ruby, alexandrite, and 1 64-nm Nd:YAG lasers have all been used successfully.