nevus of Ota

Definition: Nevus of Ota is a benign dermal melanocytosis. It involves facial skin as a macular discoloration, appearing as blotchy blue to blue gray.

Nevus of Ota is a variant of congenital nevus, which is morphologically paucicellular and resembles a common blue nevus.

Although nevus of Ota is a risk factor for uveal melanoma in white people, the development of cutaneous melanoma within nevus of Ota is a very rare occurrence with only a few reported cases.

Ota’s nevus is mongolian spot-like macular blue-black or gray-brown patchy pigmentation that most commonly occurs in areas innervated by the first and second division of the trigeminal nerve.

Acquired, bilateral nevus of Ota-like macules (ABNOM) is located bilaterally on the face, appears later in life, is blue-brown or slate-gray in color. It is not accompanied by macules on the ocular and mucosal membranes. There is also debate as to whether ABNOM is part of the Ota’s nevus spectrum.

Nevus of Ota involves the upper portion of the face, especially over the periorbital area. It also involves ocular structures such as episclera, sclera, conjunctiva, cornea, retina, uveal tract and also nasopharynx, auricular mucosa, tymphanic membrane and dura. Glaucoma and malignant melanoma are the two known ocular complications in patients with Nevus of Ota. 12-18% of these patients exhibits palatal pigmentation.

Nevus of Ota can cause facial disfigurement, resulting in emotional and psychologic distress. In rare cases, melanoma, which can be life threatening, has been reported to arise from nevus of Ota. Glaucoma also has been associated with nevus of Ota.

Epidemiology

 0.2% to 1% in the Japanese population
 congenital or acquired during adolescence

Associations

 scleral melanocytosis
 lesions of the tympanic membrane, oral and intranasal mucosa and leptomeninges
 open-angle glaucomas
 melanoma
 nevus of Ito
 phakomatosis pigmentovascularis
 nevus flammeus
 Sturge-Weber syndrome
 neurofibromatosis
 leptomeningeal melanosis
 ipsilateral intracranial meningeal melanocytoma (11883852)
 malignant melanoma (skin, meninges, ocular tissues)
 ocular anomalies (ocular acuity normal)

• pigmentation of the sclera, cornea, retina, and optic disc
• cavernous hemangiomas of the optic disc
• elevated intraocular pressure
• glaucoma (10.3%)
• ocular melanoma

Various stages of melanocytic progression caan be observed including areas resembling a nevus of Ota, blue nevus, cellular blue nevus, and melanoma.

There can be heterogeneity in the overtly malignant sections with some areas displaying expansile nodules of blander appearing spindled cells, whereas other areas were composed of epithelioid cells with higher mitotic counts and zones of necrosis. The extensive lesion can also infiltrate the soft tissue and bone.

History

 The naevus of Ota (naevus fusculocoeruleus ophthalmomaxillaris) was first described by the Japanese dermatologist M. T. Ota in 1939.

Candidates genes involved

 GNAQ, BRAF, NRAS, KIT

See also

 melanocytic tumors
 nevus of Ito
 pediatric melanoma

References

 Molecular Analysis of a Case of Nevus of Ota Showing Progressive Evolution to Melanoma With Intermediate Stages Resembling Cellular Blue Nevus. Gerami P, Pouryazdanparast P, Vemula S, Bastian BC. Am J Dermatopathol. 2010 Jan 23. PMID: 20110797