En coup de sabre is a rare subset of localized scleroderma (also known as morphea) which is characterized by a linear-shaped atrophic patch or plaque on the forehead or frontoparietal scalp. Due to its typical location, it can cause significant cosmetic disfigurement such as hyperpigmentation and fat atrophy, leading to serious psychosocial distress for patients. Various approaches for the treatment of en coup de sabre have been reported in the literature, including systemic immunosuppressants, phototherapy, topical tacrolimus, and topical corticosteroids [1]. Despite such treatments, additional treatment such as injectable fillers, autologous fat transplantation, or laser treatments is often required for aesthetic improvement of residual deformity and hyperpigmentation. Herein, we report a case of en coup de sabre successfully treated with a combination of 1,064-nm picosecond domain Nd:YAG laser and pneumatic needleless injector.

A written informed consent was obtained from the patient for the publication of this case report.

A 43-year-old female patient visited our department with an approximately 6-year history asymptomatic linear, depressed patch with hyperpigmentation on her mid-forehead (Fig. 1A). Before visiting our clinic, she was diagnosed with morphea with histopathological confirmation and treated with multiple sessions of ultraviolet A (UVA) treatment with topical pimecrolimus cream for 2 years. She also underwent multiple sessions of 1,064-nm Q-switched Nd:YAG laser for hyperpigmentation but the effect was minimal, and she was aesthetically unsatisfied. Since the lesion seems to be stable and inflammatory phase has subsided, no additional treatment with UVA or other systemic agents was done. For the hyperpigmentation, we treated with a 1,064-nm picosecond Nd:YAG laser (PicoPlus^®; Lutronic) with a spot size of 8-mm, fluence of 0.7 J/cm² with a pulse rate of 10 Hz. Then, we delivered an injection fluid composed of 20% hypertrophic glucose solution (JW Pharmaceutical) using a pneumatic needleless air-powered microjet injector device (AIRJET II^®; Union Medical) at 5 mm intervals without overlapping (50% pressure power, filling level 10, total 20 shots) (Fig. 1B). After 4 treatment sessions at 4-week intervals, improvement in hyperpigmentation and skin texture was observed. Thus, we continued treatment up to the 10th sessions, and the patient exhibited remarkable improvement of the lesion and satisfied with the cosmetic results (Fig. 1C). No serious adverse events including flare-up of en coup de sabre were observed until the 6-month follow-up. The patient reported mild discomfort and erythema after the pneumatic needleless injector session, which subsided within 3 days after the treatment.

Figure 1. Clinical photographs of a 43-year-old female patient with en coup de sabre. (A) Initial presentation at our clinic with a hyperpigmented patch on the mid-forehead. (B) Immediately after performing pneumatic needleless injector treatment. Well-circumscribed, blanching papules are seen at the injection points with mild pinpoint bleeding. (C) Marked improvement of hyperpigmentation and skin texture after ten sessions of 1,064-nm picosecond Nd:YAG laser and pneumatic needleless injector combination therapy.

Localized scleroderma is an uncommon connective tissue disorder which is characterized by excessive collagen deposition in the skin, resulting in sclerotic changes of the dermis and underlying subcutaneous tissue. Although it is often associated with cosmetic impairment, there were few clinical data on laser treatment or invasive procedures for cosmetic improvement due to concerns about disease reactivation or aggravation following postprocedural inflammatory reactions [2]. Recently, various energy-based devices including intense pulsed light, pulsed dye laser, Q-switched alexandrite laser, long-pulsed Nd:YAG laser, and CO₂ fractional laser have been reported to show promising results in the correction of telangiectasia, microstomia, skin texture, and joint contracture in a stable localized scleroderma [3].

To our knowledge, this is the first report regarding the use of combination treatment with 1,064-nm picosecond Nd:YAG laser and a pneumatic needleless injector for managing the cosmetic appearance of en coup de sabre. A pneumatic needleless injector device has been shown to induce dermal micro-trauma which stimulates fibroblasts and induce wound healing process, resulting in neocollagenesis and scar remodeling [4]. In addition, Cho et al. [5] and Kim et al. [6] have demonstrated that pneumatic injection of 20% hypertonic glucose solution induces proliferation of fibroblasts, neocollagenesis by stimulating the latent form of transforming growth factor (TGF)-β and exerts greater tissue regeneration effect compared to a 5% isotonic solution. Therefore, possible mechanisms of pneumatic needleless injecting 20% hypertonic solution for en coup de sabre might be related to 1) immediate mechanical loosening of sclerotic tissue and releasing skin tightness, similar to subcision and 2) degradation of improperly homogenized collagen bundles via modulation of TGF-β signaling during the wound repair process. Additionally, picosecond domain laser exerts photomechanical effects that selectively destroy melanosomes and minimize nonspecific photothermal damage in contrast to Q-switched Nd:YAG laser [7]. Therefore, picosecond laser may provide a safe and effective treatment for hyperpigmentation in en coup de sabre. In this case, we only used an unfractionated beam to selectively target melanin pigments. The concomitant use of a fractionated beam may be also beneficial in the treatment of en coup de sabre by promoting dermal remodeling through the formation of laser-induced optical breakdown [8]. However, further studies are needed to confirm this hypothesis. Although there are no reported cases of disease reactivation of localized scleroderma after picosecond Nd:YAG laser or pneumatic needleless injector treatment so far, clinicians should always be aware of the risk of disease reactivation.

In conclusion, our report suggests that this noninvasive combination treatment may serve as safe and effective treatment option for managing cosmetic appearance of en coup de sabre patients. It is necessary to prove its effectiveness and safety through well-designed controlled clinical studies involving more patients.

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Conceptualization: KHY. Data curation: SHS. Methodology: HSH, SYC. Visualization: HSH, SYC. Writing–original draft: SHS, KHY. Writing–review & editing: all authors.

Kwang Ho Yoo is the Editor-in-Chief of the journal but was not involved in the review process of this manuscript. Hye Sung Han is an editorial board member of the journal but was not involved in the review process of this manuscript. Otherwise, there is no conflict of interest to declare.

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