Successful treatment of hyperpigmentation from fixed drug eruption with a low‐dose and large‐spot Q‐switched 1064 nm Nd:YAG Laser

Dear Editor, Hyperpigmentation is defined as the darkening of skin's natural color due to melanin deposition in the epidermis or dermis. The incidence of medical visits for druginduced pigmentation is 1.31%.1 Fixed drug eruption(FDE) accounts for 1544.7% of all types; typical asymptomatic congestive erythema was absorbed and subsided with residual purplebrown pigmentation patches. Lesions may recur and tend to be fixed on the same site and the more frequent the recurrence, the more obvious the pigmentation. In treatment, patients especially those with FDE occurring on the face and other exposed sites, more attention is paid to refractory pigmentation left after acute lesions. Chemical peels and topical medicine (hydroquinone, arbutin, and vitamin A derivatives), etc., programs have certain effects on decreasing epidermal pigments.2 However, the treatment effect on FDEinduced dermal pigment is poor, especially in patients with type IV colored skin in China. This may be related to the histopathological manifestation of FDE, which shows vacuolar degeneration of basal layer cells and melanophagy cells in the upper dermis, with function changes and unable to effectively engulf melanin granules, namely pigment incontinence.3 In addition, natural observation and conventional sunscreen may gradually lighten some patients' pigment with time, but the above schemes cannot achieve effective satisfaction due to the long remission period or unsatisfactory efficacy. Therefore, it is particularly necessary to explore therapeutic strategies to accelerate the metabolic process of FDEinduced pigmentation, improve efficacy, and reduce adverse reactions. Pigmenttargeted laser treatment may be an option, only one case of picosecond laser treatment for druginduced pigmentation was reported abroad,4 but the availability in some institutions limits its application. Herein, we summarize and report two cases of FDEinduced pigmentation successfully treated with Qswitched laser, to provide new ideas and motivation for clinicians to deal with hyperpigmentation from FDEs. Case 1 A 24yearold female patient, FDEinduced hyperpigmentation for 4 months around the lip mucosa, and pigment was significantly deepened after recurrent (Figure 1A). Topical hydroquinone for 3 months without significant improvement, which seriously affected her social interaction and caused her extreme distress. Case 2 A 37yearold female patient, Fitzpatrick IV, FDE appeared around


Successful treatment of hyperpigmentation from fixed drug eruption with a low-dose and large-spot Q-switched 1064 nm Nd:YAG Laser
Dear Editor, Hyperpigmentation is defined as the darkening of skin's natural color due to melanin deposition in the epidermis or dermis. The incidence of medical visits for drug-induced pigmentation is 1.31%. 1 Fixed drug eruption(FDE) accounts for 15-44.7% of all types; typical asymptomatic congestive erythema was absorbed and subsided with residual purple-brown pigmentation patches. Lesions may recur and tend to be fixed on the same site and the more frequent the recurrence, the more obvious the pigmentation. In treatment, patients especially those with FDE occurring on the face and other exposed sites, more attention is paid to refractory pigmentation left after acute lesions.
Chemical peels and topical medicine (hydroquinone, arbutin, and vitamin A derivatives), etc., programs have certain effects on decreasing epidermal pigments. 2 However, the treatment effect on FDE-induced dermal pigment is poor, especially in patients with type IV colored skin in China. This may be related to the histopathological manifestation of FDE, which shows vacuolar degeneration of basal layer cells and melanophagy cells in the upper dermis, with function changes and unable to effectively engulf melanin granules, namely pigment incontinence. 3 In addition, natural observation and conventional sunscreen may gradually lighten some patients' pigment with time, but the above schemes cannot achieve effective satisfaction due to the long remission period or unsatisfactory efficacy. Therefore, it is particularly necessary to explore therapeutic strategies to accelerate the metabolic process of FDE-induced pigmentation, improve efficacy, and reduce adverse reactions. Pigment-targeted laser treatment may be an option, only one case of picosecond laser treatment for druginduced pigmentation was reported abroad, 4 but the availability in some institutions limits its application. Herein, we summarize and report two cases of FDE-induced pigmentation successfully treated with Q-switched laser, to provide new ideas and motivation for clinicians to deal with hyperpigmentation from FDEs.   Figure 1B) and three treatments ( Figure 2B), respectively, the local pigmentation obviously subsided.
Fitzpatrick in Chinese population is mostly type iv colored skin, after the occurrence of FDE, especially recurrent patients are prone to persistent dermal hyperpigmentation. Q-switched 1064/532 nm laser is regarded as gold standard for the treatment of benign pigmentation. 5 1064 nm laser ensures proper penetration depth to target dermal melanin and accelerate its metabolism, reducing epidermal melanin absorption is beneficial to reduce epidermal damage. 3 By setting the parameters to above low-dose and larger-spot can minimize mottled hypopigmentation or color deepening phenomenon after 1064 nm laser overtuning. 6  Therefore, for patients with colored skin with high epidermal melanin content, when targeting FDE-induced dermal pigmentation, we can consider this scheme to achieve better cosmetic results.

ACK N OWLED G M ENT
None.

FU N D I N G I N FO R M ATI O N
None.

CO N FLI C T O F I NTER E S T S TATEM ENT
None.

E TH I C A L A PPROVA L
None.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are openly available in 12 at https://kdocs.cn/l/chIUw P11RZaI.

CO N S ENT S TATEM ENT
The patient in this manuscript has given written informed consent to publication of their case details.