Dermatology Online Journal

Acquired bilateral nevus of Ota-like macules
Alexandria V Booth MD
Dermatology Online Journal 11 (4): 1

Department of Dermatology, New York University School of Medicine

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Abstract

A 41-year-old woman presented with a 10-year history of grey-brown macules bilaterally on lateral forehead, temples, and malar aspects. Histopathologic examination showed dermal melanocytosis. Acquired bilateral nevus of Ota-like macules (Hori's nevus) is a condition usually found in middle-aged women of Asian descent. Pathogenesis is unknown, and effective treatment has been achieved with pigment-specific lasers.

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A 41-year-old woman was referred to the Bellevue Hospital Center Dermatology Clinic for evaluation and treatment of large, dark spots below her eyes; the lesions started as small brown spots and increased in size over 10 years. Chemical peels were used in the past without success. There was no other medical or medication history. Physical examination revealed multiple, discrete, coalescing, gray-brown macules distributed over the temples, malar areas, and lateral aspects of forehead.

Figure 1	Figure 2

Histopathology shows within the papillary and upper reticular dermis, there are bipolar dendritic melanocytes that are arranged predominantly as single units between collagen bundles. Numerous pigment-laden macrophages also are identified.

Comment

Acquired bilateral nevus of Ota-like macules were first described in 1984 as blue-brown or slate-gray, small patches that occurred on the lateral sites of the forehead, temples, upper eyelids, malar areas, root of the nose, and ala nasi, without ocular or mucosal pigmentation [1]. The macules are most often seen in women of Asian descent and usually appear in the fourth or fifth decade [2].

On histopathologic examination, there are irregularly-shaped, bipolar melanocytes in the middle and upper dermis without disturbance of the normal skin architecture [1, 2]. On electron microscopic examination, there are dermal melanocytes that contain many singly dispersed melanosomes in stages II, III, and IV of melanization [2].

Acquired bilateral nevus of Ota-like macules are differentiated from bilateral nevus of Ota by the later age of onset and the lack of conjunctival, mucosal, and tympanic membrane involvement [1]. It is also distinguished from facial melanosis, Riehl's melanosis, and dermal melasma histopathologically by the presence of dermal melanocytes [2].

The pathogenesis is unknown, but proposed mechanisms include the dropping off of epidermal melanocytes, the migration of hair bulb melanocytes, the reactivation of preexisting dermal melanocytes, and the manifestation of latent dermal melanocytosis, which is triggered by dermal inflammation, atrophy, or aging-related degeneration of the epidermis and dermis [1].

Lasers are the most common treatment for this condition. Twenty-six percent of patients treated with the Q-switched Nd:Yag laser for one to two treatments, and 50 percent of patients who underwent more than two treatments had good-to-excellent clearing [5]. Over 80 percent of patients treated with the Q-switched alexandrite laser had at least a 50 percent clearing, with hypopigmentation, erythema, and hyperpigmentation as complications [3]. Prior epidermal ablation with a carbon dioxide laser has been found to increase the therapeutic efficacy of pigment-specific lasers [4].

References

1. Hori Y, et al. Acquired nevus of Ota-like macules. J Am Acad Dermatol 1984; 10:962

2. Hori Y, et al. Circumscribed dermal melanoses: classification and histologic features. Dermatol Clin 1988;6:315

3. Lam AY, et al. A retrospective study on the efficacy and complications of Q- switched alexandrite laser in the treatment of acquired bilateral nevus of Ota-like macules. Derm Surg 2001;27:937

4. Manuskiatti W, et al. Treatment of acquired bilateral nevus of Ota-like macules (Hori's nevus) using a combination of scanned carbon dioxide laser followed by Q- switched ruby laser. J Am Acad Dermatol 2003;48:584

5. Polnikorn N, et al. Treatment of Hori's nevus with the Q-switchd Nd:Yag laser. Derm Surg 2000;26:477

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