Journal review 아름다운예의원 오영상 M.D. A Retrospective Study of Q-Switched Alexandrite Laser in Treating Nevus of Ota Journal review 아름다운예의원 오영상 M.D.

BACKGROUND The Q-switched alexandrite laser (QSAL) has been clinically proven to be effective in treating nevus of Ota, but a large-scale retrospective study with long-term follow-up has never been performed. OBJECTIVE To evaluate the efficacy of the QSAL in treating nevus of Ota, the laser’s long-term side effects, complications associated with the treatments, and the recurrence rate. MATERIALS AND METHODS Eight hundred six patients (651 female, 155 male) with a diagnosis of nevusof Ota who had received a series of QSAL (wavelength 755 nm) treatments were recruited. The typical settings were fluences of 3.8 to 4.8 J/cm2 and a spot size of 3mm. Follow-ups were conducted via questionnaire with 590 patients who had completed the treatment at least 3 years earlier. RESULTS Overall, 93.9% of patients achieved complete clearance after an average of 5.2 sessions. All recurrences (0.8%) appeared beyond the previously treated sites. No long-term adverse effects, including hypopigmentation, hyperpigmentation, textural changes, and malignant transformation, were observed. CONCLUSION The QSAL is a safe and effective modality for treating nevus of Ota. Recurrence was rare and appeared beyond the previously treated sites. The authors have indicated no significant interest with commercial supporters.

Nevus of Ota is a benign dermal melanocytic nevus Nevus of Ota is a benign dermal melanocytic nevus. It usually manifests as a unilateral, mottled, blue or brownish black macule involving the sclera and the surrounding skin, innervated by the first and second branches of the trigeminal nerve. This dermatosis is more common in Asians. Previous therapies such as cryotherapy,1 dermabrasion, and skin grafting2 may be somewhat effective in certain cases, but these treatments are invasive and carry a risk of scarring or atrophy. Based on the principles of selective photothermolysis, nevus of Ota can be treated successfully using the Q-switched (QS) ruby laser, QS alexandrite laser (QSAL), and QS neodymium-doped yttrium aluminium garnet (QSNY) laser

All patients were treated with the QSAL at 755nm with a pulse duration of 60 ns (VersaPulse, COHERENT, Palo Alto, CA) using a 3-mm spot size and a 10-Hz repeat rate The fluences ranged from 3.8 to 4.8 J/cm2 and were adjusted according to clinical response. The interval between treatment sessions was 3 to 6 months. A topical anesthetic cream (eutectic mixture of 2.5% lidocaine hydrochloric acid and 2.5% prilocaine, EMLA, Astra, Sweden) was used with occlusion 1 hour before the treatment. After each session, a topical antibiotic ointment (Mupirocin, Bactroban, SmithKline & French) was applied twice a day for 7 days. Patients were advised to wear a broad-spectrum sunblock with sun protection factor (SPF)30 and protection of UVA (PA)11 during the whole treatment cycle.

Patients continued to receive serial treatments until the lesions cleared completely or there was no further improvement with ongoing treatments (Figure 1 & 2). Patients who had adhered to the whole therapeutic schedule and been followed up for more than 3 years were recruited for this study. They were interviewed using a structured telephone interview (telephone group) or an in-person appointment (appointment group) about recurrences and side effects related to their treatment. This study was performed after its protocols received approval from the Institutional Medical Ethics and Human Research Committee of China Medical University.

Figure 1. A 30-year-old male patient with nevus of Ota (type II) Figure 1. A 30-year-old male patient with nevus of Ota (type II). (A) Before treatment. (B) One year after the sixth treatment session.

Figure 2. A 24-year-old female patient with nevus of Ota (type IV) Figure 2. A 24-year-old female patient with nevus of Ota (type IV). (A) Before treatment. (B) One year after the sixth treatment session.

Figure 3. A 5-year-old female patient with nevus of Ota Figure 3. A 5-year-old female patient with nevus of Ota. (A) Before treatment. (B) One year after the fourth treatment session. (C) Five years after the final treatment, a newly developed lesion had appeared on the middle of forehead (arrow).

Adverse Effects Five hundred ninety patients were followed up for a mean of 70.8 + - 23.8 months (range 36–126 months). No persistent erythema, textural change, scarring, or sensitivity was reported in patients of the telephone or appointment group. No hypo - hyperpigmentation was observed in any of the patients in the appointment group. No malignant transformation was reported in either group. Five patients thought that their treated skin was rejuvenated.

Recurrence Only five of 590 patients (0.8%; 2 male, 3 female; mean age 17.0 years, range 5–24 years) had a recurrence after achieving complete clearance. All the recurrences appeared beyond the previously treated site (Figure 3). The mean time of recurrence was 56 months (range 32–70 months).

Hypopigmentation was the most common complication after QS laser therapy in previous studies. Kono and colleagues noted that hypopigmentation occurred in as many as 16% of patients who received QS ruby laser therapy. Chen and colleagues compared the complication rates of the QS alexandrite and QS Nd:YAG lasers in the treatment of nevus of Ota; hypopigmentation occurred in 10.5% of patients who received QSAL therapy, in 7.6% of patients who received QS Nd:YAG laser therapy, and in 38% of patients who received both (not simultaneously).

These two studies indicated that the number of treatment sessions and fluences applied were important contributing factors to this complication. In our follow-up visits, no hypopigmentation was observed in any patient This may be partly because of the fewer treatment sessions and lower fluences applied in our study, as well as the much longer follow-up period. In some cases, hypopigmented macules would repigment after a long period of time. Hyperpigmentation was less common than hypopigmentation, varying from 2% to 6% in previous studies.6,12 No case of hyperpigmentation was seen in our follow-up visits, possibly because of the differences in study designs

Conclusion QSAL is safe and effective in the treatment of nevus of Ota. Longer treatment intervals may reduce the total number of treatment sessions needed, as well as adverse effects such as hypo- and hyperpigmentation. Recurrence was rare and might be reduced by complete clearance Although no malignant transformation was reported in our study, a longer follow- up period is needed.