Treatment of Laser-Responsive Dermal Pigmentary Conditions in Type III-IV Asian Skin With a 755-nm Picosecond Pulse Duration Laser: A Retrospective Review of Its Efficacy and Safety

Abstract

BACKGROUND Picosecond lasers have become very popular in the treatment of hyperpigmentation. OBJECTIVE Evaluating the efficacy and safety of picosecond 755-nm laser in treatment of nevi of Ota (NO) and Hori's nevi (HN) in Asians with Fitzpatrick skin Types III/IV. METHODS A retrospective review of patient records at the National Skin Center, Singapore, from 2015 to 2017. Three independent blinded dermatologists assessed pre-and-post treatment photographs using the physician's global assessment (PGA) score (0-clear, 1-almost clear, 2-mild, 3-moderate, and 4-severe). RESULTS There were 18 cases of NO and 11 cases of HN. Mean treatment sessions were 2.22 (NO; range 1–6) and 3.82 (HN; range 1–6). In the NO group, mean pre-and-post treatment PGA scores were 3.1 and 1.3, respectively (1.8 point change, p -value 0.0002), and average fluence used was 2.02 J/cm 2 (range: 1.02–2.38). In the HN group, mean pre-and-post treatment PGA scores were 2.6 and 1.1, respectively (1.5 point change, p -value 0.004), and average fluence was 2.08 J/cm 2 (range: 1.98–3.40). Eleven patients (37.9%) experienced postlaser erythema, and 1 (3.4%) patient developed transient postlaser hypopigmentation. No permanent hyper/hypopigmentation was seen. CONCLUSION The picosecond 755-nm laser is effective in the treatment of dermal pigmentary conditions in Asians with Fitzpatrick skin Types III/IV, with minimal risk of postlaser complications, and compared with the center's past experience with the Q-switched nanosecond 1064-nm laser, results in faster and more effective pigment clearance.

Advancements in Laser Therapies for Dermal Hyperpigmentation in Skin of Color: A Comprehensive Literature Review and Experience of Sequential Laser Treatments in a Cohort of 122 Indian Patients

“…The study also suggested a trend toward greater clearance with QS ruby in type-IV patients [23]. The ps-QS 755 nm Alexandrite laser has shown superiority over its ns-QS counterpart in terms of fewer treatment sessions required, though PIH was noted in a few cases with darker skin tones [20] (Table 2). Finally, while not formally classified as a dermal nevus, certain subtypes of epidermal nevi may have dermal components (e.g., hair follicles in Becker's nevus) that need to be addressed in order to reduce the overall appearance of pigmentation in such cases; (refer to authors' study in Section 3.2 of discussion).…”

“…The condition can be cosmetically disfiguring [23]. Prior to the introduction of the QS lasers, treatment approaches like dermabrasion and cryotherapy often resulted in dyspigmentation or scarring [20]. For nevus of Ota, the 1064 nm QS Nd:YAG laser stands out as the most extensively used treatment modality, offering effective results, especially in higher Fitzpatrick skin types.…”

“…Hori's nevus and blue nevi also respond well to QS laser treatment [13]. Ps-or ns-ranged QS pigment (Nd:YAG, Ruby, Alexandrite) and vascular (KTP or Potassium titanyl phosphate) lasers have all demonstrated effective clinical outcomes and gained broad acceptance as the established standard of care in terms of studies as well as formal recommendations [20]. However, millisecond lasers and IPL have not been found to be effective [16].…”

“…Within the dermal layer, melanosomes absorb brief bursts emitted by the device, providing sufficient energy to break down tissue while minimizing collateral thermal damage. Despite advancements, ns-QS lasers still pose challenges with multiple treatments and instances of dyspigmentation and scarring, attributed to the main mechanism of photothermal damage, an excess of which may trigger inflammation and alteration of melanocytes in the basal epidermis, especially in darker skin tones [20,21]. This prompted the development of a technology with optimal photoacoustic effects for this patient population, viz., the ps-lasers, operating in the sub-nanosecond range (10 −12 s).…”

“…Approved by the FDA for skin applications in 2012, ps-lasers, characterized by extremely brief PDs and substantial peak power density, rely on photoacoustic destruction rather than photo-thermolysis. The heightened photomechanical/photoacoustic effect and reduced heat diffusion into nearby structures potentially offer improved clinical outcomes and decreased thermal injury compared to ns-domain devices [20]. In terms of wavelength, these include the ps-Alexandrite (755 nm) and ps-Nd:YAG (1064 nm) lasers.…”