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Nevus of Ota

Last updated Dec. 9, 2018

Nevus of Ota is a benign skin condition with hyperpigmentation that is found on the head and neck region, mostly in the white of the eye.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Congenital Melanosis Bulbi
  • Naevus of Ota and Ito
  • Oculomucodermal Melanocytosis

What is Nevus of Ota? (Definition/Background Information)

  • A nevus (plural nevi) is a mole on the skin that can occur on any part of the body
  • Nevus of Ota is a benign skin condition with hyperpigmentation that is found on the head and neck region, mostly in the white of the eye
  • This condition is predominantly observed in females. Nevus of Ota can be a congenital condition, but is not hereditary, meaning that it does not run in the families
  • The cause of Nevus of Ota is unknown, but it could be due to an abnormal accumulation of melanocytes during the fetal development stage
  • They do not present any significant complications, but may cause cosmetic concerns in some individuals. Nevus of Ota in the eye is also associated with a higher risk of glaucoma
  • Treatment is generally not required for a Nevus of Ota unless it presents cosmetic issues, in which case a laser surgery may be helpful
  • The prognosis of Nevus of Ota is generally excellent with or without treatment, since these skin lesions are frequently benign

Who gets Nevus of Ota? (Age and Sex Distribution)

  • Nevus of Ota is a skin condition that is normally present at birth, but can occur during adolescence too
  • Both males and females are affected, but females are affected much more than males in a 5:1 ratio
  • All racial and ethnic groups are at risk, though Nevus of Ota is more frequent among the Japanese population and other Asian races compared to Europeans, Americans, or Africans

What are the Risk Factors for Nevus of Ota? (Predisposing Factors)

Currently, no clear risk factors have been identified for Nevus of Ota. However, they are more common in:

  • Females (nearly 85% of the cases are observed in them)
  • People of Japan and some countries of Asia have a higher risk

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Nevus of Ota? (Etiology)

  • The cause of Nevus of Ota formation is unknown
  • However, some researchers believe that it may be formed due to abnormal accumulation of melanocytes (cells producing melanin) in the fetal development stage
  • Nevus of Ota is not a hereditary condition, even though a congenital presentation is noted

What are the Signs and Symptoms of Nevus of Ota?

Nevus of Ota may not present any major signs and symptoms in most cases. The general features of the skin condition include:

  • It is a benign skin lesion that occurs as a hyperpigmented skin patch
  • The skin patch may be bluish to bluish-brown in color
  • The head and neck region is mostly affected, especially the face; either one side, or both sides of the face may be involved
  • In two-thirds of the cases, the sclera of the eye (the white part of the eye) is affected. The condition may be unilateral or bilateral, meaning that either one eye or both eyes may be affected
  • Nevus of Ota can occur in the mouth too; in the hard palate

How is Nevus of Ota Diagnosed?

A Nevus of Ota is diagnosed through the following tools:

  • Complete physical examination with evaluation of medical history
  • Dermoscopy: It is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
  • Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
  • Serial photographs, which can help one record a changing skin condition over time
  • Skin biopsy: A skin biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

Note: In majority of cases, a biopsy is not necessary. But they may be performed if there is an area of concern, or to rule out other conditions presenting similar signs and symptoms, or to exclude melanoma (a cancerous skin condition).

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Nevus of Ota?

The complications from Nevus of Ota may include:

  • If the skin lesion is present in the eye(s), there is a higher risk of glaucoma (an eye disorder causing vision loss)
  • Rarely, malignant melanoma is known to develop from the site of the lesion, and hence, close follow-up is important and necessary
  • In some individuals, it may give rise to cosmetic concerns and stress
  • Recurrence of the tumor on its incomplete removal and removal

How is Nevus of Ota Treated?

The treatment measures for Nevus of Ota include:

  • In mild cases, the healthcare provider may choose to regularly observe the benign condition; a “wait and watch” approach may be followed. In such cases, no treatment is generally required
  • In case of cosmetic reasons, a laser surgery is found to be beneficial
  • Nevus of Ota can also be excised through electrocautery surgical procedure too
  • Follow-up care with regular screening and check-ups are important and encouraged

How can Nevus of Ota be Prevented?

Current medical research has not established a way of preventing the occurrence of Nevus of Ota.

What is the Prognosis of Nevus of Ota? (Outcomes/Resolutions)

The prognosis of Nevus of Ota is excellent even if no treatment is provided and only periodic observation maintained, since typically it is a benign skin condition.

Additional and Relevant Useful Information for Nevus of Ota:

  • This condition was first described by Dr. Ota, a Japanese physician, in 1939, and hence the term ‘Nevus of Ota’
  • Nevus of Ota should not be confused with Mongolian spots. Besides, unlike Mongolian spots, Nevus of Ota does not disappear with time
  • There is no evidence to prove that the tumor formation is influenced by one’s dietary choices
  • Cleaning the skin too hard with strong chemicals or soaps may aggravate the skin condition. Care must be taken avoid strong soaps and chemicals that could potentially worsen the condition
  • The presence of dirt on the body is not a causative factor for the condition. However, it helps to be clean and hygienic, which may help the condition from getting worse

What are some Useful Resources for Additional Information?


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Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Jan. 7, 2016
Last updated: Dec. 9, 2018