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Successful treatment of microneedle fractional radiofrequency for refractory depressed scars in buttocks: A case report

Dear Editors, The treatment for depressed scar is a challenge for clinicians. We report a 25yearold woman who had several scattered, erythematous and deep sunken in various sizes from 10 to 25 mm and 8 mm in depth on her bilateral buttocks after recovering from skin infection 10 years ago was diagnosed as depressed scars combined folliculitis (Figure 1). The scars had been treated via several methods which could not certainly be described by patient in other hospitals, but these were ineffective. Due to the unattractive appearance, the patient came to our hospital for help. Considering the complicated situation, microneedle fractional radiofrequency (MNFR, generated by Shenzhen Peninsula medical Inc,), a minimally invasive and effective technology, had been chosen as the treating method. Fusidic acid was also locally applied for folliculitis. The treatment was applied once every three months for three times in total and three passes per time. Mild erythema and swelling without petechiae were noted after the treatment but were relieved on the second day. After the first treatment, obviously improving volume was observed (Figure 2A), and faded hyperpigmentation was observed after the second time (Figure 2B). Following the final time of treatment, depressed scars almost completely disappeared (Figure 2C). None of complication and recrudescence was observed during the 2 years followup (Figure 2D). Depressed scars, often caused by injuries, result in defects of the dermal and subcutaneous tissues, which are depleted of collagen, elastin, and adipose in the subsequent healing process, forming a permanent depressed scar. This type of scar always shows depression and uneven texture on the skin surface which is always related to cosmetic impairment, emotional problems, and even functional limitations for patients.1 Although various therapeutic modalities such as excision, medium depth chemical peels, injection of various filler materials, hot plasma, carbon dioxide and ablative fractional laser treatment can improve depressed scars, the effects are limited and postprocedure wound care for lesions on the buttock is a challenge due to the special anatomic site. MNFR, which could deliver radiofrequency energy into the deep dermis or subcutaneous tissue via microneedles and leaving the surface unharmed, had been chosen as the method. This novel minimally invasive technique has been commonly recognized for improving photoaged skin, acne scars, thick pores, hyperpigmentation and so on.2 However, it is the first report of large area and deep hip depressed scars by this strategy. Several researches have studied the mechanisms of MNFR, mainly focusing on the dermal or subdermal tissue heated by the energy delivered by microneedles, thereby causing collagen contraction and denaturation which is induced by a woundhealing process, resulting in skin remodeling and the production of collagen, elastin in the treated skin.3 In this case, the depth of microneedles extended into 1– 3mm that it had affected both dermis and subcutaneous tissue layers which are composed of fascia and adipocytes. In rats’ vivo experiment, a precursor of adipocytes from superficial fascia which is composed of fascial fibroblasts and connective tissues with a widespread distribution has been found.4 In mouse’ vivo experiment, the dermis fibroblasts might originate from prefabricated matrix in the subcutaneous fascia fibroblasts in skin wound healing.5 Several researches have also revealed the possibility of adipose transdifferentiate into fibroblast during the woundhealing process.6 According to these studies, we suppose that the ability of MNFR to treat depressed scars might be also related to its ability to stimulate the fascial fibroblast or adiposes which might transdifferentiate into adipocytes and fibroblasts to synthesis collagens to fill the deficient volumes. However, further mechanical and clinical researches for the potential of MNFR to treat the refractory depressed scars are required.