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

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 drug-induced 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. Case 1 A 24-year-old female patient, FDE-induced 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 37-year-old female patient, Fitzpatrick IV, FDE appeared around the lips 1 week after oral antibiotic for gingivitis. The acute lesions subsided after timely treatment and left brown hyperpigmentation patches (Figure 2A). The above two patients with FDE around lips both had obvious persistent hyperpigmentation after recovery. This facial pigmentation affects image; patients sought for a non-trace state as soon as possible. Patients are firstly advised to avoid taking or exposure to suspected sensitizing agents and drugs with similar structures, daily sun protection. Considering the long remission period of topical decolorizing agent and some patients' non-responsiveness, Q-switched laser (SPECTRATM, Lutronic) targeted treatment scheme for removing pigment was finally adopted. The specific parameters were as follows: wavelength 1064 nm, spot diameter 8 mm, energy 170 J/cm2, and repetition rate 5 Hz. The number of pulses per treatment varies from 700 to 1500 according to pigmentation area. A slight heat or prick could be felt at the starving point, and a light erythema may be observed and disappear completely spontaneously within a few hours. Treatment once a month and no obvious adverse reactions occurred after multiple treatments. After five (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 By 3-5 treatments, local pigmentation fade evenly to almost complete elimination. At the same time, it overcomes the adverse reactions such as stimulation and drug resistance of traditional long-term maintenance treatment with topical drugs, significantly shortened the recovery interval, improved efficacy and satisfaction. 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. None. None. None. None. The patient in this manuscript has given written informed consent to publication of their case details.