Nevus of Ota is a periocular pigmentary condition characterized by the formation of a benign nevus of dermal melanocytic origin. First described by Ota in 1939, this condition typically presents as a unilateral gray-blue hyperpigmentation of the face in the distribution of the ophthalmic and maxillary branches of the trigeminal nerve. Nevus of Ota commonly affects regions of the eye, such as the sclera, choroid, and iris, and other adjacent structures like the orbit, meninges, and palate.
Onset is most commonly seen at birth or early childhood; however, there is a second peak of onset in adolescence that is attributed to hormonal changes. The pigmentation can increase in size and color up until adulthood.
Clinical studies indicate that nevus of Ota occurs more commonly in the Asian population, with the incidence reported as high as 1.1% in one Japanese study. However, larger, recently conducted community-based studies suggest a lower rate of occurrence, with an investigation of 3914 Chinese children attending a clinic in Canada uncovering only one case, for an incidence rate of 0.034%.
Nevus of Ota is classified as a dermal melanocytosis along with nevus of Ito, Mongolian spots, and dermal melanocyte hamartoma. The pathophysiology of these dermal melanocytoses is thought to be related to the premature arrest of melanocyte migration in the dermis, which leads to an increase in the number of melanocytes in the skin and characteristic gray-blue hyperpigmentation. Each of these conditions tends to affect a different part of the body—nevus of Ota occurs in the trigeminal distribution, nevus of Ito in the acromioclavicular area, Mongolian spots classically near the sacrum, and dermal melanocyte hamartomas in various dermatomal distributions of the body. The histology of nevus of Ota generally features an increased number of melanocytes irregularly scattered in the papillary and reticular dermis.
While nevus of Ota itself is a benign condition, it has been reported to be associated with malignant melanomas of the skin, brain, orbit, and choroid.[3,8,9,10] In a large retrospective analysis of 7872 patients with uveal melanoma, Shields and colleagues found clinical evidence of melanocytosis in 3% of patients. They also reported that patients with both uveal melanoma and oculodermal melanocytosis had double the risk for metastasis in comparison to patients without melanocytosis. These results highlight the need for close monitoring and examination of patients with nevus of Ota, as the pigmentation can obscure the development of thin tumors. Sequential ophthalmic examination and imaging, including fundus photography, optical coherence tomography, and ultrasonography, are useful in evaluating patients to assess for malignant transformation.
Management also should include monitoring for glaucoma, as a study by Teekhasaenee and colleagues reported increased intraocular pressure in 10.3% of patients with nevus of Ota.
While nevus of Ota is a relatively benign condition that can be managed conservatively, most patients choose to remove the lesion for cosmetic reasons. The first-line treatment is Q-switched laser therapy, which involves the use of short pulses of high-energy lasers for the targeted destruction of dermal melanocytes and has proven to be effective. Common adverse effects of laser therapy—mostly mild—include pain during the procedure, postoperative inflammation and edema, and hypopigmentation. Cryotherapy and dermabrasion were once the primary therapeutic options for nevus of Ota[15,16] but have been largely replaced by laser therapy due to inferior effectiveness and significant adverse effects (eg, scarring). The only noninvasive option for treating nevus of Ota involves masking the lesion with the use of makeup and camouflage materials.
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Cite this: A Child With Pigmentation of the Eye - Medscape - Oct 10, 2017.