Nevus of Ota: Clinical Aspects and Management

Henry H.L. Chan, MB, FRCPG, FRCPE, Taro Kono, MD

Disclosures
In This Article

Clinical and Histologic Aspects of Nevus of Ota

Nevus of Ota typically presents as unilateral blue-black or slate gray macules that are located in the distribution of the first or second branches of the trigeminal nerve (Figure 1). Tympanic membrane, ocular, oral, and nasal mucosal involvement is common. As already stated, most patients tend to develop the nevus at birth or shortly thereafter, although some patients can develop it as late as 20 years of age. Therefore, diagnosis is mainly clinical and a biopsy is rarely needed. Tanino[3] classified nevus of Ota according to the extent of the cutaneous involvement as follows:

  • IA: Upper/lower eyelid; periorbital and temporal

  • IB: Infrapalpebral, nasolabial fold, and zygomatic region

  • IC: Forehead

  • ID: Nasal

  • II: Over upper and lower eyelids, periocular, zygomatic, cheek, and temple

  • III: Scalp, forehead, eyebrow, and nose

  • IV: Bilateral

Nevus of Ota

Histologically (Figure 2), elongated dendritic melanocytes are scattered widely in the papillary to mid reticular dermis. These melanocytes stain weakly with 3,4-dihydroxyphenylalanine, which indicates that they retain the ability to produce melanin. Hirayama and Suzuki[13] examined the histological findings of 450 cases of nevus of Ota and classified the condition according to the distribution of the dermal melanocytes as follows:

  • Superficial (S): Dermal melanocytes are located in the superficial layer of the dermis.

  • Deep (De): Dermal melanocytes are located in the deep layer of the dermis.

  • Diffuse (Di): Dermal melanocytes are evenly spread throughout the dermis.

  • Superficial dominant (SD): Diffuse distribution of dermal melanocytes, but with a greater concentration in the superficial layer.

  • Deep dominant (DD): Diffuse distribution of dermal melanocytes, but with a greater concentration in the deep layer.

Histologically elongated dendritic melanocytes

The ratio of S, SD, Di, DD, and De was 3:2:3:1:1, and they suggested that the histologic classification would be useful in predicting therapeutic outcomes, with the superficial type more likely to respond to treatment than the deep type. Indeed, their hypothesis was later confirmed by others,[14] who performed skin biopsies before and after Q-switched alexandrite laser surgery on 55 patients with nevus of Ota. Their findings indicated that the therapeutic outcome depends upon the depth rather than the color of the nevus. Under electron microscopy, the dermal melanocytes from nevus of Ota contain many single dispersed melanosomes that are usually fully melanized. Basal lamina and lamina lucida can be found around some of the melanocytes. Extracellular periodic acid-Schiff-stain negative sheaths, which consist of fine filaments, surround the melanocytes. One recent study[15] of the melanosomes of nevus of Ota melanocytes found that they might be related to the peculiar skin color of the nevus. Some of the abnormal types are similar to those that are found in dysplastic nevi and melanomas.

The purpose of disease classification is to define the extent or severity of the disease so that the clinical outcome can be predicted. An accurate disease classification also allows effective communication among researchers. In the past, when there was no effective treatment for nevus of Ota, Tanino's classification served the above purpose by describing the extent of the nevus. Hirayama and Suzuki's classification, while able to predict the outcome, is of limited value, as skin biopsy is usually not performed in these patients. With advances in laser surgery, satisfactory clinical outcome can now be considered as complete clearing without any residual cosmetic disfigurement. To better reflect the prognosis in terms of laser response, our group[16] examined 119 laser-treated patients for evidence of coexisting birthmarks and extracutaneous involvement. Two observers also assessed the pre- and post-treatment clinical photographs for evidence of periorbital under-response (Panda's sign), which is defined as the degree of periorbital laser clearing that is significantly less than clearing in the other area. The observers considered 47.8% of the patients with periorbital pigmentation to have significant periorbital under-response (Panda's sign); 10.1% had other birthmarks, and extracutaneous involvement was seen in 31.4% of the patients. Based on these observations, nevus of Ota has been reclassified into the following types according to laser response[6]:

  1. Nevus of Ota without periorbital involvement, another birthmark, and extracutaneous involvement.

  2. Nevus of Ota with periorbital involvement, but without another birthmark and extracutaneous involvement.

  3. Nevus of Ota with another birthmark but without extracutaneous involvement.

  4. Nevus of Ota with extracutaneous involvement.

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