Novel treatment of Hori's nevus: A combination of fractional nonablative 2,940-nm Er:YAG and low-fluence 1,064-nm Q-switched Nd:YAG laser

INTRODUCTION

Acquired bilateral nevus of Ota-like macules (Hori's nevus) is common among Asian women.[12] Clinically, it resembles the nevus of Ota characterized by bilateral blue-brown macules on the forehead, malar, and nasal areas.[3] However, the nevus of Ota is a congenital lesion, whereas Hori's nevus appears in the third to fifth decades of life. Hori's nevus also does not involve the conjunctivae and mucous membranes. Histologically, melanocytes are distributed evenly throughout the dermis in the nevus of Ota while melanocytes are in the papillary and middle portions of the dermis in Hori's nevus.[45]

Lasers have been effective in treating nevus of Ota.[6789] These include QS Nd:YAG, ruby laser, and alexandrite laser.[101112] Dermabrasion has been found to be effective as well.[13] However, treatment responses have been noted to be less effective for Hori's nevus.[12] For Hori's nevus, multiple expensive laser treatments have to be used. This takes a long time and complete resolution is not always possible.

Two reports have described combination laser therapy for Hori's nevus. Manuskiatti et al. used a scanned CO₂ laser and QS Nd:YAG laser[14] while Hock et al. used a 532-nm potassium titanyl phosphate (KTP) laser and QS Nd:YAG laser.[15] Both showed better results with combination therapy than with Nd:YAG alone.[1415]

In this paper, we present a novel technique of using a fractional 2,940-nm Er:YAG and a 1,064-nm QS Nd:YAG laser to successfully treat a series of Hori's nevus.

MATERIALS AND METHODS

Five Chinese women were enrolled in the study. Exclusion criteria included chemical peel, laser, intense pulsed light treatment in the last year, and pregnancy. The age of the patients ranged 30-46 years. Only those subjects with bilateral malar lesions were included. Four patients had Fitzpatrick skin type III and one had skin type IV. Informed consent was obtained.

The patients had their faces cleansed before the treatment. There was no anesthesia involved. We used the fractional nonablative 2,940-nm Er:YAG laser (SP Spectro, Fotona, Ljubljana, Slovenia) with a fluence of 0.7 J/cm², spot size 12 mm, and frequency 15 Hz. We carried out a full-face single-pass treatment. Subsequently, we performed a second pass and third pass over Hori's nevi bilaterally till the clinical endpoint of skin whitening was observed. No wiping was performed between the passes. We then used the 1,064-nm Q-switched (QS) Nd:YAG laser. (RevLite, Cynosure Co., Fremont, CA, USA) at a fluence of 2.0 J/cm², frequency 2 Hz, and spot size 4 mm. We used multiple passes over Hori's nevus till erythema with mild petechiae appeared. The Er:YAG laser was performed as a singular session. The QS Nd:YAG laser treatment was repeated weekly for 3 more consecutive weeks.

The skin was kept cool during treatment with cryogen spray. After laser treatment, the patients applied topical fusidic acid for 3 days and sunscreens during daytime (for the entire study duration).

Photographs were taken before treatment and 1 month after the last laser treatment. These were evaluated by three independent physicians. The degree of improvement was graded into the following five levels of response: no change (0%), noticeable lightening (<25% improvement), mild lightening (25-50% improvement), moderate lightening (50-75%), and marked lightening to complete clearance (75-100%).[14] The patients also graded their treatment responses subjectively. They were followed up clinically for a total of 3 months after the laser treatment for monitoring of postinflammatory hyperpigmentation (PIH) and recurrence.

RESULTS

All the patients experienced 5-7 days of erythema and skin scaling following the first treatment session. This downtime was attributed to the Er:YAG. When the scaling resolved within the week, the patients reported noticing a lightening of the Hori's nevus. At the end of 1 month after the laser treatment started, three independent physicians scored them.

All the physicians reported that all the patients had >80% improvement in their pigmentation, with two patients (skin type III) achieving complete 100% clearance [Figures 1 and 2]. Based on the patients’ subjective assessment, all the five patients expressed satisfaction and felt that their pigmentation had improved. The patients were to be followed up for another 2 months (without further treatment). No PIH, hypopigmentation, or recurrence was seen.

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Figure 1

Pretreatment photo

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Figure 2

After 1 month of laser treatment

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DISCUSSION

There are reports on the use of lasers to clear Hori's nevus.[101112] However, obtaining a satisfactory response takes multiple treatments and complete clearance is not always possible. Research on methods to improve the therapeutic effectiveness of lasers on Hori's nevus have shown that response rates have improved with combination lasers.[1415161718] However, there are no reports on the Er:YAG and Nd:YAG laser combination.

In this study, we demonstrated that the Er:YAG and Nd:YAG combination is safe with minimal downtime and no complication. The results were also very good (>80% improvement) and the condition did not recur after 3 months of follow-up. Such clearance rates with minimal treatment session are unprecedented.

Combination laser therapy is synergistic and effective. The following are postulated mechanisms: First, when the Er:YAG laser is used prior to the Nd:YAG laser, it partially ablates the epidermis that removes epidermal melanin. This allows less competition and less scattering of the Nd:YAG laser, leading to more effective penetration.[14151819] Second, the occurrence of an increased collagen fiber density due to the effects of the Er:YAG may mask the residual underlying dermal melanocytes, making the nevus appear lighter.[672021]

The other benefit of combination therapy is that with two lasers working on different targets synergistically, we can adopt a lower fluence for each laser type. This reduces the chance of complications such as PIH.

Research has demonstrated that the Nd:YAG laser and CO₂ laser combination also work well.[14] However, we believe that our Er:YAG and Nd:YAG combination is more ideal. This is because CO₂ is an ablative laser and can cause erythema that takes about 3 months postoperatively to resolve.[14] CO₂ laser can also cause bleeding and scarring. Comparatively, the use of the nonablative Er:YAG has a downtime of only 5-7 days that includes erythema on the first 2 days followed by generalized peeling over the next 3-5 days. Therefore, our combination therapy is ideal because it provides a solution that has a balance of effectiveness and yet minimal downtime and complications.

It is imperative for research to be conducted to elucidate the exact mechanism by which combination therapy works. It is also important to conduct larger prospective trials to elucidate the exact settings for the lasers. It may also be worthwhile to study a comparison between CO₂ laser or Er:YAG laser as a combination laser and Nd:YAG laser. It is also important to follow up for even longer durations to monitor recurrence.[1011]