Melanocytic nevus is a common skin phenomenon and does not require medical intervention in most cases. However, for the purpose of beautifying the appearance, the treatment of moles in exposed areas has become the choice of many people. Although traditional treatments such as surgical excision, CO₂ laser or erbium laser are effective, there is a risk of scar formation and pigment abnormalities, especially for moles with larger diameters. Q-switched Nd:YAG laser (1064nm) was previously mainly used for deep pigmented diseases such as Ota nevus and tattoos. There has long been a lack of sufficient clinical data on its safety and effectiveness in the treatment of melanocytic nevus. Based on this, Kim et al. (2012) conducted relevant research, and the results showed that this laser therapy showed good results in the treatment of melanocytic nevus, and significantly reduced the incidence of scars compared with traditional CO₂ laser.

DESIGN AND IMPLEMENTATION

Research Design and Implementation

This study included 2064 patients with benign melanocytic nevus (28 males, 2036 females, aged 15-59 years old), all of whom were Fitzpatrick III-V skin types, including congenital, acquired melanocytic nevus and blue nevus. The characteristics of the nevus body are uniform color (light brown to dark brown), flat or slightly convex, diameter ≤10mm, and the patients have no scar physique. 40 minutes before treatment, the mole area was anesthetized on the surface, followed by Nd:YAG laser (wavelength 1064nm, spot size 2mm, frequency 10Hz, energy 10-12J/cm²) treatment. A single mole treatment took about 2-4 seconds. During the operation, the local skin was pulled and pressed to assist hemostasis. After the operation, the skin dressing was applied twice a day and changed every two days until the epithelial tissue was completely repaired (Figure 1).

Figure 1 Source: Youmai Aesthetics

The whole process of Q-switched Nd:YAG laser (1064nm) treatment of melanocytic nevus. (A) Before treatment; (B) Treatment was given after topical anesthesia, and the skin was tightened during the treatment to inhibit bleeding; (C) Immediately after treatment, the skin was covered with a sterile paper towel and pressed vertically to stop bleeding; (D) Afterwards, an external skin dressing was applied; (E) Epithelialization was completed 7 days after laser treatment; (F) The nevus basically disappeared 14 days after laser treatment.

CRITICAL ISSUES

Key research questions

Data showed that nearly 70% of patients' nevus bodies could be completely removed by a single laser treatment, and 30% of patients required 3 treatments to achieve the removal effect. Compared with CO₂ laser, this treatment significantly reduced the scar formation rate (Figure 2). The average recovery period of treatment was 7-10 days, and there was no infection, significant scarring, or pigment abnormality throughout the process. Only mild stinging, bleeding during treatment, and slight redness and swelling after surgery occurred.

Figure 2 Source: Youmai Aesthetics

RECURITY ANALYSIS

Efficacy and safety analysis

As the largest sample size study of its kind, the results show that about 70% of nevus can be removed with a single treatment, and the remaining 30% require 2-3 treatments (repeated treatment after epithelial repair), and the efficacy is comparable to that of CO₂ laser. For multiple nevus, this therapy can achieve centralized treatment in a short period of time, reflecting the advantages of high efficiency and patient tolerance, and postoperative care is simple.

The study confirmed that the safety of this laser therapy is comparable to that of pigment-specific lasers such as Q-switched ruby laser and alexandrite laser. Its longer wavelength (1064nm) gives a deeper depth of action, which can more thoroughly remove nevus cells, and no obvious scars were observed in all treatment cases. In view of the fact that this laser treatment is more prone to bleeding than traditional lasers, the study effectively controlled intraoperative bleeding through a hemostasis scheme of local skin traction combined with pressing with sterilized paper towels. In addition, reducing thermal damage to the skin and appendages has been shown to be a key factor in promoting epithelial regeneration, which can shorten the recovery period and reduce the risk of scarring.

It should be noted that this therapy may only be applicable to nevi with a diameter of ≤10mm. For nevi of larger size or special parts such as the nose, some studies have shown that the effect of Q-switched Nd:YAG laser is limited, while CO₂ laser may have more advantages (Figure 3); other studies have pointed out that this laser can only dilute some melanocytic nevi and it is difficult to completely remove them (Figure 4).

CONCLUSIONS AND PROSPECTS

Conclusion and Prospect

In summary, Q-switched Nd:YAG laser (1064nm) provides a safe, efficient and convenient treatment option for melanocytic nevus with a diameter of ≤10mm, with excellent cosmetic effects and low scar risk, and is expected to become a new preferred choice for clinical treatment. In the future, the research scope needs to be further expanded to explore its application potential in special parts and larger nevus.

References

[1] Kim YJ, Whang KU, Choi WB, et al. Efficacy and Safety of 1,064 nm Q-switched Nd:YAG Laser Treatment for Removing Melanocytic Nevi. Ann Dermatol. 2012, 24(2):162-7.
[2] Parasramani S, Oberai C, Amonkar K, et al. Q-switched Nd:YAG Laser to Treat Nevomelanocytic Nevi. J Cutan Aesthet Surg. 2009, 2(2):88-91.
[3] Rosenbach A, Williams CM, Alster TS. Comparison of the Q-switched alexandrite (755 nm) and Q-switched Nd:YAG (1064 nm) lasers in the treatment of benign melanocytic nevi. Dermatol Surg 1997,23: 239-44.
[4] Reda AM, Taha IR, Riad HA. Clinical and histological effect of a single treatment of normal mode alexandrite (755 nm) laser on small melanocytic nevi. J Cutan Laser Ther .1999, 1(4):209-15.
[5] Minakawa S, Takeda H, Korekawa A, et al. Q-switched ruby laser therapy and long-term follow-up evaluation of small to medium-sized congenital melanocytic naevi. Clin Exp Dermatol. 2012, 37(4):438-40.
[6] Zhao Bian. Chinese Journal of Clinical Dermatology [M]. Nanjing: Jiangsu Phoenix Science and Technology Press, 2017:1418-9.

The core founding team of Suzhou Foremed Legend Medical Technology Co., Ltd. comes from Peking University and other well-known universities at home and abroad. Foremed Legend focuses on the design, development and application of high-end medical beauty optoelectronic equipment based on compliance and product strength., is committed to becoming a leading company in the field of high-end medical aesthetic optoelectronic equipment, a provider of integrated intelligent solutions for diagnosis and treatment, and a pioneer of medical aesthetic data integration platform.

Through tackling a series of underlying key technologies, Foremed Legend has now independently developed a number of high-end medical equipment such as picosecond laser therapy devices, long pulse laser therapy devices, intense pulsed light therapy devices, photoacoustic imaging skin detection devices and cold air therapy devices, and continues to deepen the research and development of core product technologies, using better technical solutions to benefit the vast number of beauty seekers.

Adhering to the principle of technology for good, Foremed Legend will work with industry and ecological partners to bring more safe and effective medical aesthetic optoelectronic equipment and integrated diagnosis and treatment solutions to the global medical aesthetic market.