Efficacy of microneedle radiofrequency therapy in the treatment of senile purpura: A prospective study

Abstract

Background

Radiofrequency (RF) devices have been used for skin rejuvenation and treating skin laxity. It may also be effective for senile purpura (SP) based on its action of promoting neocollagenesis with minimal epidermal damage. This study aimed to evaluate the efficacy and safety of microneedle RF for treating SP of the forearms in elderly.

Material and methods

In this prospective study, 23 patients who underwent a single session of microneedle RF device (GENIUS, Lutronic Co., Korea) therapy for SP were enrolled. Histopathological features were assessed 1 week before and 8 weeks after therapy. The total amount of collagen and elastic fibers were measured using the computer vision method, and epidermal thickness and the number of blood vessels were analyzed using ImageJ. The clinical improvements were evaluated by blinded evaluators and the patients using investigator global assessment (IGA) and patient global assessment (PGA), respectively. Data regarding the number of purpuric lesions and the size of the largest lesion were collected via a telephone survey.

Results

The total amount of collagen and elastic fibers, and mean epidermal thickness tended to improve after RF treatments, although they did not reach statistical significance. The locally estimated scatterplot smoothing curve showed decreasing tendency in both size and number of purpuras as weeks progressed. PGA showed very satisfied in 65% of patients and IGA showed 39% near‐total improvement and 43% marked improvement. There were no serious adverse events.

Conclusions

Microneedle RF therapy induces remodeling of dermal circumstances with minimal epidermal impairment. It may be a promising therapeutic option for SP.

1. INTRODUCTION

Senile purpura (SP) is characterized by purpuric macules and patches mainly on the extensor surfaces of the forearms and hands and typically affects elderly. It is not associated with coagulation disorders or nutritional deficiency, and providing reassurance to the patients is the mainstay of treatment. ¹ However, because of its appearance, SP leads to significant psychological burdens, hampering interpersonal interactions, and self‐esteem. ² Moreover, with the increasing elderly population, SP has a functional dimension beyond cosmetics and appearance. ³ SP is a key morphological feature of dermatoporosis, a progressive skin condition affecting the elderly, which results in complications, such as linear skin tears, lacerations, and delayed wound healing, and is susceptible to bleeding and cutaneous infection. ³ , ⁴ , ⁵ As a preceding sign of dermatoporosis, SP should be treated and prevented to avoid complications.

Limited treatment options exist for SP. Studies have investigated several topical and oral treatments for SP with variable efficacy, including topical hyaluronic acid fragments with retinaldehyde, topical heparin‐binding epidermal growth factors, topical tretinoin, subdermal injection of calcium hydroxyapatite, oral vitamin C supplementation, daily protein intake, and oral dehydroepiandrosterone. ⁵ , ⁶ , ⁷ , ⁸ Although laser surgery is effective for several dermatological conditions and is the treatment of choice to improve photodamaged skin, ² , ⁵ , ⁷ , ⁸ , ⁹ , ¹⁰ , ¹¹ , ¹² , ¹³ , ¹⁴ , ¹⁵ , ¹⁶ , ¹⁷ , ¹⁸ few studies have evaluated the efficacy of laser surgery in SP. Durso et al. demonstrated a significant reduction in the SP resolution time after treatment with long‐pulsed, frequency‐doubled neodymium‐doped yttrium–aluminum garnet (Nd:YAG) laser (532 nm), although its ability to prevent new lesions was not evaluated. ¹⁹ Siperstein et al. conducted a study on intense pulsed light (IPL) as a treatment for SP and concluded that it is safe and effective in improving the appearance and preventing further lesions. ²⁰ Nevertheless, the limitation of IPL in treating SP lies in its non‐ablative mechanism, which may require multiple series of treatment sessions to obtain the desired effects; however, comparative studies are lacking for exact comparisons.

Radiofrequency (RF) devices create electrical currents that convert to thermal energy when it encounters the resistance of tissue in its conduction pathway. It has been introduced in the field of cosmetics to induce dermal remodeling. It does not depend on the chromophore but on the electrical properties of the target tissue; therefore, it can be safely used in all Fitzpatrick's skin types. ² , ¹⁴ However, achieving an adequate temperature in the deeper dermis may lead to overheating of the epidermis, leading to scarring, blistering, and post‐inflammatory hyperpigmentation. ¹⁷ Microneedle RF devices were developed to enhance dermal heating without thermal injury to the epidermis. It uses an insulated needle to penetrate the epidermis with minimal heating while effectively delivering the desired energy to predetermined depths. It enables the dermal temperature to reach the optimal range of 65–70°C, which overcomes the heating deficiency seen with other lasers, including the transepidermal RF system. ¹⁷ This optimal dermal heating induces the production of elastin and collagen by creating a controlled volumetric coagulation zone. ²¹ Microneedle RF therapy is considered minimally invasive because epidermal injuries are limited to mechanical penetration, similar to simple microneedling. ²² Most SP patients have a thin epidermis and impaired dermal connective tissue, ²³ which can benefit from vigorous dermal remodeling with neocollagenesis and neoelastogenesis while minimizing damage to the epidermis.

This study aimed to investigate the long‐term efficacy and safety of a microneedle fractional RF system in the treatment of SP. We hypothesized that minimal ablative treatments, including RF therapy, will require fewer treatment sessions compared with non‐ablative treatments, including IPL therapy.

2. MATERIALS AND METHODS

2.1. Patients

Twenty‐three SP patients were enrolled in this prospective study. SP was diagnosed based on the clinical presentation of well‐demarcated violaceous purpuric macules and patches of various sizes, with or without atrophic scars, on forearms. These purpuric patches, induced by negligible trauma, easily recurred and resolved within 2 weeks. All patients were aged 71–78 years (mean, 74.43 ± 3.08 years) and had Fitzpatrick skin types III or IV. The lesions were restricted to forearms. Patients with concurrent active infection or recognizable cutaneous disorders in the forearm were excluded. Patients treated with systemic antiplatelets/anticoagulants or topical, intraarticular, or systemic corticosteroids were included, considering these agents’ role in the etiology of SP. However, topical steroids were discontinued during the study.

This study was approved and monitored by the Institutional Review Board (IRB) of the Veterans Health Service Medical Center, Republic of Korea (IRB no: 2020‐09‐007) and conducted per the Declaration of Helsinki. Written informed consent was obtained from all patients.

2.2. Devices and treatment protocol

A microneedle fractional RF device (GENIUS, Lutronic Co., Korea), which has a disposable single‐use tip consisting of 7 × 7 electrodes, was used in this study. GENIUS has an impedance power control system that can regulate the energy delivered through each microneedle automatically and create a precise coagulation zone. This real‐time tissue impedance monitoring prevents unpredicted electric energy from being delivered to the target tissue with varying impedance. Furthermore, the improved sharpness of the microneedle enables the required energy to be positioned at the desired depth. It directly delivers energy with power setting up to 50 W with 0.5–3.4 mm depth. ²⁴ The applicable lesions were locally anesthetized with topical 4% lidocaine cream for 1 h before the procedure. The initial penetration depth and energy per pin were 1.5 mm and 10 mJ/pin, respectively; these were adjusted according to the thickness of the dermis based on the histological evaluation of the baseline skin biopsy and the degree of subjective symptoms, including pain and the immediate surface response of each patient during treatment, and ranged from 0.6 to 2.2 mm and 4 to 10 mJ/pin, respectively. The treatment was delivered in a single pass, and saline wet dressings for 5–10 min and vaseline were applied. Each patient underwent two treatment sessions at 8‐week intervals.

2.3. Assessments of efficacy

Histological features were assessed 8 weeks after the first treatment, and clinical assessments were performed 24 weeks after the first treatment.

2.4. Histological analysis

Two 4‐mm punch biopsy skin samples from purpuric patches on the dorsal surface of the forearm were collected at 9‐week intervals. The baseline and follow‐up biopsies were performed 1 week before and 8 weeks after the first session. The samples were fixed using formalin and embedded in paraffin. All samples were stained with Masson's trichrome (MT) to identify the collagen, Verhoeff–Van Gieson (VVG) stain for elastic fibers, and immunohistochemical staining with CD31 antibodies for vessel structures. Each slide was imaged using the Montage technique by Lionheart FX (BioTek, USA) at 200× magnification for analysis. The amounts of collagen and elastic fibers were measured using MT and VVG staining intensity, respectively. For quantitative analysis, we used threshold segmentation method to separate the target area from the background based on the red, green, and blue color models that were generated for collagen and elastic fibers. Next, the pixel units of the segmented area were counted. The epidermal thickness was measured using ImageJ (Rasbands, W.S., ImageJ, US National Institute of Health, Bethesda, Maryland, USA) by a physician. Four individual sites were selected for calculating the mean epidermal thickness. CD31‐stained vessels were counted using ImageJ. Dermal changes were evaluated in a 1000 × 500 μm² region of the upper‐to‐mid dermis in each sample.

2.5. Clinical assessment

Images of the affected area were obtained under the same light and background using a digital camera (Canon EOS 800D, Japan). Clinical improvements and complications were assessed by both patients and dermatologists. Two blinded physicians evaluated the efficacy of the treatment on the overall skin conditions in terms of texture, tightness, and smoothness using the investigator's global assessment (IGA) scale, which utilizes quartile grading (grade 0 = no improvement; grade 1, 1%–25% = minimal improvement; grade 2, 26%–50% = moderate improvement; grade 3, 51%–75% = marked improvement; and grade 4, 75%–100% = near‐total improvement). IGA scores were assessed 8 and 24 weeks after the first session. The efficacy assessment by patients was evaluated using questionnaires about purpuric patches and the patient global assessment (PGA), which uses a four‐point scale (0 = not satisfied, 1 = somewhat satisfied, 2 = satisfied, and 3 = very satisfied). Each week after the first treatment until 24 weeks of follow‐up, patients telephonically answered questionnaires regarding existing purpuric patches and their total number, the size of the largest patch, and any newly developed subjective symptoms. Patients completed the PGA at the end of the follow‐up. Pain during the treatment was evaluated using the numeric pain rating scale (NPRS), which uses a 0–10 scale, wherein “0” represents no pain and “10” represents extreme pain. Information regarding the duration of pain, edema, erythema, pruritus, hyperpigmentation/hypopigmentation, and the presence of secondary infection were collected.

2.6. Statistical analysis

Paired t‐test and Wilcoxon signed‐rank test were used to evaluate pre‐ and posttreatment differences. We used a locally estimated scatterplot smoothing (LOESS) model ²⁵ to describe the nonlinear trend of the numbers and sizes of purpura due to the imbalance in our data. Statistical significance was set at p < 0.05. All analyses were performed using R 4.1.2 (R Foundation for Statistical Computing, Vienna, Austria).

3. RESULTS

3.1. Patient demographics

Among the 23 patients (mean age, 74.43 years), 22 were men, and 4 were current smokers. Detailed medical histories are described in Table 1. During the study, five patients were on aspirin, nine were on antiplatelets, and four were on both agents. Two patients had a history of systemic steroid treatment, whereas 11 patients were on topical steroids. No patients were undergoing intraarticular corticosteroid injections.

TABLE 1.

Demographics and medical histories of patients

Patients	N
Sex	23
Male	22
Female	1
Mean age (years)	74.43 ± 3.08
Prescribed medication
Systemic steroid	2
Aspirin	5
Antiplatelet	9
Topical steroid	11
History of smoking
(+)	4
(−)	19

3.2. Assessment of efficacy

3.2.1. Histologic analysis

Eight weeks after the first session, the mean collagen density increased from 2257106.4 ± 1197611.6 to 3009894.6 ± 1541382.2 (Figure 1A,B) and the mean elastic fiber value increased from 831762.6 ± 476213.9 to 854829.3 ± 744392.8 (Figure 2A,B); however, the differences were not statistically significant (p > 0.5 for both) (Table 2). The mean epidermal thickness in the first and second biopsy samples were 0.044 and 0.049 mm, respectively. Although the epidermal thickness was higher in the second biopsy, it was not statistically significant (p > 0.05). The vessel count increased significantly from 35.06 ± 17.04 to 43.88 ± 16.09 posttreatment (p = 0.021) (Figure 3A,B). The use of prescribed medication or smoking did not influence the efficacy of the treatment.

FIGURE 1.

Dermal remodeling associated with collagen production after microneedle radiofrequency therapy. Senile purpura lesions were biopsied at baseline (A) and 8 weeks after the first session (B). Dermal collagen is increased after therapy (blue). All images are Masson–Trichome stained at 200× magnification.

FIGURE 2.

Dermal remodeling associated with neoelastogenesis after microneedle radiofrequency therapy. Senile purpura lesions were biopsied at baseline (A) and 8 weeks after the first session (B). Dermal elastin is increased after therapy (black). All images are Verhoeff Van Gieson stained at 200× magnification.

TABLE 2.

The difference in mean collagen and elastic fiber amounts between pre‐ and post‐therapy

Subject	Amount (pixel)	p‐value*
Collagen (pre)	2257106.4 ± 1197611.6	0.062
Collagen (post)	3009894.6 ± 1541382.2
Elastic fibers (pre)	831762.6 ± 476213.9	0.9078
Elastic fibers (post)	854829.3 ± 744392.8

^* p‐values <0.05 are considered statistically significant.

FIGURE 3.

Vessel counts increased 8 weeks after microneedle radiofrequency therapy (B) compared with the baseline (A). Vessels are stained with CD31 antibodies and shown at 200× magnification.

3.2.2. Clinical assessment

All 23 patients completed two sessions of the treatment without major complications. Compared with the baseline, all patients showed clinical improvements regarding purpura, epidermal atrophy, and skin texture (Figure 4A–D). Regarding the first IGA, average 2% of the patients showed near‐total improvement, 19.5% showed marked improvement, 30.5% showed moderate improvement, and 48% showed minimal improvement. The second IGA demonstrated higher grades with 19.5% showing near‐total improvement and 19.5% showing marked improvement (Table 3). The patient satisfaction score was very satisfied in 65% of patients, whereas 30% and 4% of patients answered satisfied and somewhat satisfied, respectively (Table 4). Patient‐answered self‐assessments describing the sizes and numbers of purpuric patches are presented in Figures 5A,B. The LOESS curve showed decreasing trends in both the sizes and numbers of purpuric patches over time. Continuing prescribed medication or smoking status did not influence IGA and PGA. The average NPRS was 5 (4–6), and all patients opted for the second session.

FIGURE 4.

(A) Before and (B) 6 months after the microneedle radiofrequency (RF) therapy for senile purpura (SP) on the left forearm of a 77‐year‐old man. (C) Before and (D) 6 months after the microneedle RF therapy for SP on the right forearm of a 74‐year‐old man

TABLE 3.

Clinical assessment by the investigator

IGA score	First IGA a	First IGA	Second IGA	Second IGA
1	57% (13/23)	39% (9/23)	44% (10/23)	26% (6/23)
2	17% (4/23)	44% (10/23)	17% (4/23)	35% (8/23)
3	22% (5/23)	17% (4/23)	17% (4/23)	22% (5/23)
4	4% (1/23)	0% (0/23)	22% (5/23)	17% (4/23)

Note: The first IGA was conducted at 8 weeks after the first session, and the second IGA was conducted at 24 weeks after the first session. The IGA uses a quartile grading system: grade 0 = no improvement; grade 1, 1%–25% = minimal improvement; grade 2, 26%–50% = moderate improvement; grade 3, 51%–75% = marked improvement; grade 4, 75%–100% = near‐total improvement.

^a IGA: investigator's global assessment.

TABLE 4.

Clinical assessment by patients

Score	PGA a
0	0% (0/23)
1	4% (1/23)
2	30% (7/23)
3	65% (15/23)

Note: PGA scores were assessed at 24 weeks after the first session. PGA uses a of four‐point scale: 0 = not satisfied, 1 = somewhat satisfied, 2 = satisfied, 3 = very satisfied.

^a PGA: patient global assessment.

FIGURE 5.

(A) The number of purpuras based on telephone surveys answered by each patient. The black circular dot represents the number of patients who had the equivalent number of purpuras on the Y‐axis. The black linear line represents the mean number of purpuras, and the blue linear line shows their change in tendency. (B) The size of the largest purpura, as reported by each patient through telephone surveys. The black circle dot represents the number of patients who had the equivalent size (mm) of purpuras on the Y‐axis. The black linear line represents the mean size of purpuras, and the blue linear line shows their change in tendency.

3.3. Adverse events

During the follow‐up, there were no serious adverse events, including infection, persistent pain, and hyper/hypopigmentation. Mild‐to‐moderate pain and temporary erythema were observed during the treatment; multiple small petechiae were observed during and shortly after the needle insertion. Nevertheless, these side effects were short‐lived and well‐tolerated.

4. DISCUSSION

The histological features of SP include epidermal and dermal atrophy, erythrocyte extravasation, marked solar elastosis, and progressive loss of collagen that is replaced by abnormal elastic fibers. ¹ , ⁴ , ²³ Although the typical clinical presentation of SP is ecchymosis, ruptured vessels are not observed, and the density of dermal microvasculature is decreased. ¹ The contribution of increased microvascular permeability and the loss of adequate mechanical protection supported by connective tissue, such as collagen, have been proposed to cause erythrocyte extravasation that can induce ecchymosis from negligible trauma. ¹ , ⁶

Herein, microneedle RF therapy led to improvements in dermal histology and clinical features. The average estimated pain during the procedure was NPRS score 5 and significant side effects, including infection, post‐inflammatory hyper/hypopigmentation, and scarring, were not observed.

The mean total collagen and elastic fibers were increased after 8 weeks of the first laser in patients with SP, although it was without statistical significance. The use of transepidermal or microneedle RF devices in patients with SP is yet to be reported. However, the effect of transepidermal or microneedle RF in the treatment of skin laxity or rejuvenation has been evaluated. ¹⁰ , ¹¹ , ¹² , ¹⁴ , ²¹ Previous studies that quantitatively evaluated the efficacy of transepidermal or microneedle RF treatment consistently showed increased collagen. ¹⁰ , ¹¹ Suh et al. demonstrated increased collagen density in the papillary dermis and reticular dermis. ¹⁰ El‐Domyati et al. revealed an increase in the thickness of the collagen band at the dermo‐epidermal junction and type I and III collagen levels. ¹¹ In other studies using a qualitative method, increased collagen density and neocollagenesis were observed in the dermis. ¹⁴ , ²¹ Herein, the quantity of collagen increased by ∼1.3 folds after the treatment.

The literature regarding elastin content is discordant. In a previous study, elastin content significantly increased after using a microneedle RF device. ²¹ Other studies using transepidermal RF therapy for skin laxity reported increased elastic fibers. ¹⁰ , ¹² One study regarding facial rejuvenation reported decreased total elastin content in six patients. ¹¹ Similar conflicting results were seen in our study. Although total elastic fiber content increased by ∼1.02 folds after therapy, approximately half of the patients showed reduced elastin content. Elastic fibers in the dermis have a highly organized architecture composed of perpendicularly placed microfibrils with large‐diameter elastic fibers. ¹⁰ In photodamaged skin, including SP, irregular elastotic material accumulates under the epidermis. The decline of elastic content after RF treatment can be explained by the downward displacement of irregular solar elastotic material in the papillary dermis with the restoration of perpendicular elastic fibers. ¹¹ In patients with severe solar elastosis, simple quantitative evaluation is inadequate because the treatment improves the quality of elastic fibers.

The epidermis of SP patients is atrophic. ¹³ Herein, the mean epidermal thickness increased from 0.044 to 0.049 mm, although it was not statistically significant (p = 0.21). El‐Domyati et al. reported a significant increase in epidermal thickness caused by epidermal hyperplasia after multiple sessions of transepidermal RF therapy, whereas other study reported decreased epidermal thickness. ¹⁰ , ¹¹ These findings were attributed to the difference in the number of treatment sessions and overall skin tightening induced by dermal collagen remodeling. ¹⁰ Furthermore, the number of blood vessels is reduced in SP and photodamaged skin than in the skin of younger subjects and the photo‐protected skin of the elderly. ¹ , ²⁶ Chronic sun exposure induces a less amicable environment for the maintenance of normal vasculature and function, leading to deficient nutritional support for the dermal matrix. ²⁶ Our study showed a significant increase in the number of blood vessels in the dermis posttreatment, which may contribute to the recovery of dermal blood flow and improve the extracellular matrix in SP.

Dermatoporosis is known to result from the use of topical or systemic corticosteroids. ⁵ More severe symptoms may develop in patients who are treated with corticosteroids. ²⁷ SP is also influenced by the administration of aspirin and anticoagulants, which can trigger or exacerbate preexisting lesions. ²⁷ , ²⁸ Aspirin use is associated with delayed purpura after laser therapy and is avoided during the recovery period. ²⁹ However, antiplatelet agents and corticosteroids are used by the elderly for various critical medical conditions, including cardiovascular disease, ischemic stroke, and rheumatic diseases. ³⁰ , ³¹ , ³² Caution should be taken when considering the discontinuation of these medications to avoid flaring up of underlying conditions. We conducted a real‐world study on the elderly population while continuing the previously mentioned drugs and evaluated the effects of the treatment. Herein, the improvement in collagen and elastic fibers were not significantly different in patients with continued medications or smoking than in those without. Moreover, medications and smoking did not affect changes in the number of vessels, IGA, PGA, and epidermal thickness.

Some studies reported improvements in overall skin condition, including texture, smoothness, and tightness in patients treated for skin rejuvenation. ¹⁵ , ¹⁶ Our study also showed clinical improvements in the following aspects: Overall, 21.5% of patients demonstrated >50% improvement at 8 weeks in the first IGA, whereas 39% of patients demonstrated >50% clinical improvement at 24 weeks in the second IGA. Regarding the PGA score at 24 weeks, patients showed considerably high satisfaction scores: Overall, 30% of patients were satisfied and 65% of them reported very satisfied. Regarding patients’ self‐assessment questionnaires, the LOESS curve showed decreasing tendency in both sizes and numbers of purpuras. The purpura was induced by RF treatment within 2 weeks of the first session; however, after week 8 when the second treatment session was completed, there were no increasing tendencies regarding sizes and numbers of purpuric lesions. This reflects a decreasing pattern of the lesions. Therefore, the histopathological improvement in the dermis corresponded to the decreased numbers and sizes of purpuras.

There is a higher risk of complications in the forearm than in the face after laser treatment. However, no severe side effects, including scarring and hyper‐/hypopigmentation and excluding immediate pain during treatment and purpura induced by RF treatment in those with marked severe atrophic skin, were seen. Moderate pain and inducement of purpura by RF treatment itself may be a potential downside of therapy. However, all patients wished to proceed to the second session, and treatment‐induced purpura decreased thereafter, compared with that after the first session. To our knowledge, this is the first study to report the efficacy of an RF device for treating SP. Nevertheless, there are a few limitations. First, the weekly telephone survey had an inconsistent response rate. Despite thorough patient education regarding follow‐up, many calls were unanswered. Second, we included numbers and sizes of purpura, which were estimated by patients answered questionnaries during the first 2 weeks after treatment, which may affect the total amount of number and size of purpuric lesions. Third, the representative square sections of the biopsy samples, which were examined through the computer vision method, contained appendages in variable amounts. This could have affected the results of the total amount of collagen and elastin fibers. Lastly, although SP affects both sexes, our study included mostly men because the subject pool was limited due to the characteristic of the Veterans hospital.

5. CONCLUSION

Microneedle RF treatment induces remodeling of dermal circumstances followed by clinical improvements lasting following 6 months after treatment, without any serious side effects. Although microneedle RF treatment did not reach significant changes in parameters concerning collagen and elastic fiber, more studies with larger subjects or the one with multiple treatment session may better analyze its effect more fluently. This minimally invasive therapy may be considered a promising therapeutic modality for SP.

CONFLICTS OF INTEREST

The authors have stated explicitly that there are no conflicts of interest in connection with this article. Written informed consent was obtained from all patients for these images.

Baek G, Kim MH, Jue M‐S. Efficacy of microneedle radiofrequency therapy in the treatment of senile purpura: A prospective study. Skin Res Technol. 2022;28:856‐864. 10.1111/srt.13225

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.