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.
