Expanding endications of the excimer laser for disorders of hypopigmentation: Equivocally seeing the light
Aug. 31, 2016
The excimer laser is a reasonably effective modality for treating vitiligo. Other disorders of hypopigmentation, such as a nevus depigmentosus (ND), or post-inflammatory hypopigmentation (PIH) secondary to lichen striatus (LS) may be distressing to patients (or their parents). Is the excimer laser a viable option for these patients?
Bae et al have published two studies addressing each condition, respectively. Fourteen patients with ND were treated with the 308-nm excimer laser at an initial dose of 125 mJ/cm2, which was increased by 50 mJ/cm2 in each subsequent session until posttreatment erythema occurred. The patients’ median age was 7.7 years (range 1.4 to 24.6). The median number of treatment sessions and duration of treatment were 41 (range, 24 to 97) and 5.6 months (range, 3.7 to 13.6), respectively. Ten patients (71.4%) showed complete pigmentation after a median treatment duration of 5.2 months. The remaining 4 patients showed excellent (n = 1), moderate (n = 1), or poor (n = 2) pigmentation levels. A diffuse pigmentation pattern was predominant. Of 6 patients followed up at approximately 2-month intervals after completion of treatment, 4 (66.7%) showed loss of pigmentation at the treatment site 3 to 6 months later, and 1 (16.7%) showed no recurrence of ND 1 year after treatment. The authors (appropriately) concluded that controlled trials are warranted to determine the efficacy of this treatment (1).
In the study of PIH due to LS, the authors used a similar protocol on 12 patients. If the erythema persisted for more than 48 hours, the treatment was suspended until the erythema resolved and was resumed with a dose reduction of 50 mJ/cm2. Eleven patients (91.7%) demonstrated complete response to the excimer laser treatment after a median treatment duration of 3.3 (range 1.9 to 6.2) months and a median of 17 (range 9 to 35) treatment sessions, while the remaining 1 achieved 85% repigmentation following 202 treatments delivered over 41.9 months. The duration of follow-up of this study was not stated. The authors again recommended that this modality be studied with controlled trials (2).
The results of these studies are not surprising — I would expect a high recurrence rate for a nevoid process and a reasonably good response for a self-limited disease such as LS. According to Paller and Mancini in the latest (5th edition) of Hurwitz, “Lichen striatus usually resolves spontaneously within 3 to 24 months (mean duration, 6 months), but occasionally lasts longer (up to 3.5 years) and often leaves an area of hypopigmentation that subsequently disappears.”
Insurance issues (i.e. approval for treatment) aside, I am reluctant to use the excimer laser for either condition; for ND recurrence is likely and because LS will spontaneously resolve anyway (regardless of treatment with topical steroids or calcineurin inhibitors). Even though I am confident that this is a safe therapy, we still have patients (or their parents) sign a consent form stating that “it is possible that with any form of UV light that an increased incidence of skin cancer may occur later in some patients, usually only after many UV light treatments”. According to Park et al, the excimer laser has not been utilized long enough for the true risk of skin cancer to be defined (3). Unless there were extenuating circumstances for treating either condition with the laser, for now I will continue my current practices of reassurance for ND and topical therapy for LS.
1. Bae JM, et al. Treatment of nevus depigmentosus using the 308-nm excimer laser: A retrospective study of 14 patients. J Am Acad Dermatol 2016; 75: 626-7.
2. Bae JM, et al. Effectiveness of the 308-nm excimer laser on hypopigmentation after lichen striatus: A retrospective study of 12 patients. J Am Acad Dermatol 2016; 75: 637-9.
3. Park KK, et al. A review of monochromatic excimer light in vitiligo. Br J Dermatol 2012; 167: 468-78.
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