Page 55 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-28 Benign Growths

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 melano-
cytes. 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. Nevus of Ito
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 loca-
tions, 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 unilat-
eral in nature. Nevus of Ota manifests as a bluish to Nevus
blue-gray macule with indistinct borders that fade into of Ota
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 blue-
gray 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. Nevus of Ota low power. Pigmented mela- Nevus of Ota high power. Pigmented melanocytes with
Pathogenesis: Under normal circumstances, melano- nocytes are spread out within the dermis. elongated dendritic processes are seen amongst the
cytes migrate during embryogenesis from the neural dermal collagen bundles.
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 mela-
nocytes to collect on the face or on the shoulder,
respectively. There does not appear to be a genetic Because of the psychological and social hardships Use of the 1064-nm neodymium:yttrium-aluminum-
inheritance pattern. engendered by these cosmetically disfiguring lesions, garnet (Nd:YAG) laser has resulted in the most success
Treatment: These are benign lesions that require therapy is appropriate, albeit difficult. If only small in treating these lesions, and it can be used in patients
no therapy. It is not unreasonable to monitor them areas are involved, cosmetic makeup may be used to of almost any skin type. Q-switching of the laser is a
clinically for the rare development of malignant trans- camouflage the region. Topical therapies with hydro- method that has been shown to increase its efficacy.
formation. Most patients present for therapy because quinone and tretinoin have shown minimal to no effect Q-switched ruby, alexandrite, and 1064-nm Nd:YAG
they are bothered by the appearance of the lesions. on the pigmentation. lasers have all been used successfully.

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 41