Tuesday, March 31

Nevus of Ota

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What is nevus of Ota?
Nevus of Ota is a hamartoma of dermal melanocytes. Ota lesion was first described by Dr. Masao.T. Ota, from the University of Tokyo, Japan in 1939 as "nevus fuscoceruleus opthalmomaxillaris".
Ota lesion is also known as "congenital melanosis bulbi" or "oculodermal melanocytosis". Ota lesion presents as a blue/grey patch on the facial skin, ocular area and/or oral/nasal mucosal surfaces. The lesions occur in the areas covered by the first and second (ophthalmic and maxillary) branches of the trigeminal nerve. The hyperpigmentation is usually unilateral and in several cases it involves the sclera.

Nevus of Ota is caused by entrapment of melanocytes in the dermal layer. Ito lesion, Hori's macule and Mongolian spot also occur due to the entrapment and hamartomatous growth of melanocytes. In Ito lesions, only shoulder and upper arm are involved. Mongolian spots appear on lumbosacral region. Hori's macule is not present at birth and often affects both sides of the face. Though Ota lesions are mostly congenital, there are reports of a few cases acquired during puberty, indicating the possible role of hormones.
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Amiya Kumar Mukhopadhyay described a very rare presentation of simultaneous presence of unilateral Ota lesion, bilateral Ito lesion and palatal lesions in a male patient.

The incidence of these lesions in women is nearly five times more than men. It is more prevalent in Asian, African and East Indian populations and very rare among caucasian people. After onset, nevus of Ota may keep pace with the child's growth and may slowly and progressively enlarge and darken in color. The lesion usually become stable in appearance once adulthood is reached. Patients had reported of fluctuations in color of these lesions with environmental and health factors. Tanino had classified Ota lesions into type I (mild), type II (moderate), type III (intensive) and type IV (bilateral).

Nevus of Ota pathogenesis

The exact etiology of Ota lesion is still unknown. These lesions are caused by the presence of melanocytes in the dermis and the bluish/greyish coloration of the lesion is due to Tyndall effect of the dermal melanocytes. The failure of the melanocytes/melanoblasts from the neural crest to migrate to the epidermis during the embryonic stage is postulated as a cause. Another view is that the lesions are formed due to active production by intradermal melanocytes or due reactivation of pre-existing latent dermal melanocytes. Though specific genetic cause is not identified, a familial case has been reported. Exogenous and endogenous factors such as warm or cold weather, emotional stress, fatigue and insomnia may alter the intensity of color. Hormonal fluctuations as in menstrual cycle and menopause may increase the intensity of pigmentation.

Nevus of Ota treatment

Small disfiguring lesions can be covered up by cosmetic camouflage. Topical therapy appears to be ineffective. Other treatment modalities such as dermabrasion, micro surgery and cryotherapy may produce scars.
Ota lesion in the sclera
Nevus of Ota
Laser treatment and intense pulsed light are used to destroy these melanocytes. Multiple treatments with a combination of devices may be required. There is always the likelihood of these lesions recurring.

Sanjeev Aurangabadkar reported his study to evaluate long-term safety and efficacy of QYAG5 Q-switched Nd:YAG Laser Treatment of Ota lesion. Fifty patients with Ota lesions underwent multiple treatments over a period of one year with a Q-switched Nd:YAG laser (QYAG5, Palomar, USA). He reported excellent improvement in a majority of the patients and there were no significant adverse effects. Transient post-inflammatory hyperpigmentation was observed in some patients with resolution in two months. There was no recurrence of Ota lesion in one year of follow up.

Nevus of Ota complications

In rare cases melanoma has been reported to arise from the Ota lesions. Most of cases of malignant melanoma developing from the lesions are mainly found in skin. Ocular melanoma has been reported in the choroid, orbit and iris, in association with a Ota lesion. Some patients may develop intracranial neoplasia. Cherungottil V Radhadevi et al. reported a rare case with malignant transformation in oculodermal melanosis.

Ota lesion may give rise to ocular complications such as increased intraocular pressure and glaucoma. Lidija Magarasevic et al. reported a case of an appearance of unilateral glaucoma in a Caucasian female patient with the acquired, ipsilateral nevus of Ota.
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Reference:
1.Lidija Magarasevic, Zihret Abazi. “Unilateral Open-Angle Glaucoma Associated with the Ipsilateral Nevus of Ota,” Case Reports in Ophthalmological Medicine, vol. 2013, Article ID 924937, 3 pages, 2013.
2.Ravi Prakash Sasankoti Mohan, Sankalp Verma, Amit Kumar Singh, Udita Singh. ‘Nevi of Ota: the unusual birthmarks’: a case review. BMJ Case Rep. 2013; 2013: bcr2013008648.
3.Jitender Solanki, Sarika Gupta, Nisha Sharma, Meenakshi Singh, Sumit Bhateja. Nevus of Ota”- A Rare Pigmentation Disorder with Intraoral Findings. J Clin Diagn Res. 2014 Aug; 8(8): ZD49–ZD50.
4.Cherungottil V Radhadevi, Kakkuzhiyil S Charles, Vasu K Lathika. Orbital malignant melanoma associated with nevus of Ota. Indian J Ophthalmol. 2013 Jun; 61(6): 306–309.
5.Gaurav Sharma, Archna Nagpal. Nevus of Ota with Rare Palatal Involvement: A Case Report with Emphasis on Differential Diagnosis. Case Rep Dent. 2011; 2011: 670679.
6.Amiya Kumar Mukhopadhyay. Unilateral Nevus of Ota with Bilateral Nevus of Ito and Palatal Lesion: A Case Report with a Proposed Clinical Modification of Tanino's Classification. Indian J Dermatol. 2013 Jul-Aug; 58(4): 286–289.
7.Sanjeev Aurangabadkar. QYAG5 Q-switched Nd:YAG Laser Treatment of Nevus of Ota: An Indian Study of 50 Patients. J Cutan Aesthet Surg. 2008 Jul-Dec; 1(2): 80–84.
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Image source: http://en.wikipedia.org/wiki/File:Nevus_013.jpg
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