Laser and Light-Based Treatments for Pigmented Lesions
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AESTHETIC FOCUS Laser and light-based treatments for pigmented lesions BY PAOLO BONAN AND NICOLA BRUSCINO The authors detail the types of lasers and light-based devices that can be used in the treatment of epidermal and dermal pigmentations. kin colour differences have, for coherence and collimation and these vessel wall rupture and haemorrhaging. The centuries, been associated with characteristics differentiate laser light photothermal effect occurs when the energy the economic, political and social from non-laser light, such as intense pulsed of the irradiated photons is turned into heat Sstatus of a person; therefore, light (IPL). The absorption of photons by a due to the absorption of the photons by the appearance of a new pigmentation specific target is the scope of every laser the chromophores. The consequences may may imply a negative, emotional and treatment in order to cause a biological vary depending on the degree of heating psychological state. Non-white racial / effect; during this process all the energy reached in the target chromophore, the ethnic groups (African-Americans, Hispanics delivered by the photons is transmitted to duration of the target at that temperature, and Asians) often seek medical procedures the target structures, the chromophores. and lastly, the capacity to spread the heat to for the removal of pigmentation disorders Dermatological laser treatment changed the surrounding tissues. The photochemical due to the greater incidence of congenital radically in 1983 thanks to the introduction effect occurs when the absorbed photons and acquired pigmentary disorders among of the selective photothermolysis theory affect the cellular metabolism or influence these groups. by Anderson and Parrish, defining how to the signaling cascade. The consequences of These epidermal pigmentations are localise thermal injury to the target tissue, the photochemical effect include increased characterised by the melanin content in the thus minimising the damage to surrounding cell proliferation and migration, modulation epidermis or dermo epidermal junction: areas by choosing the adequate wavelength of growth factors, cytokines and other • Ephelides of light that the chromophore inside the mediators, increased tissue oxygenation, • Solar lentigo target tissue absorbs. and increased healing of wounds. • Lentigo simplex The absorption depends mainly on the Several laser and light devices are • Seborrheic keratoses matching of the wavelength of the photons available on the market for treating pigment • Dermatosis papulosa nigra with the absorption peak of a particular alterations: Q-switched neodymium- • Cafè-au-lait macules chromophore. The absorption by melanin, doped:yttrium aluminium garnet laser • Naevus spilus. ranging between 400 and 750nm, is (Nd:YAG) (532-1064nm), pulsed dye laser maximal in the ultraviolet area, decreasing (PDL) (595nm), Q-switched ruby laser Dermo epidermal lesions show the melanin throughout the visible region. (694nm), Q-switched alexandrite laser pigment at the epidermal and dermal The light absorption can cause three (755nm), picosecond alexandrite laser position: different types of biological effects in the (755nm), intense pulsed light (IPL) (590- • Post inflammatory hyperpigmentation skin: photomechanical, photothermal and 1200nm), as well as nonselective lasers, • Melasma photochemical. The photomechanical erbium:YAG laser (2940nm) and carbon • Becker’s naevus effect occurs when very short laser pulses, dioxide laser (CO2) (10600nm) through its • Junctional and compound melanocytic nanoseconds for the Q-switched laser fractional modality too [1-8]. nevi or picoseconds for the picosecond laser, • Congenital melanocytic nevi. produce very strong energies; in this Lasers and lights way the tissue undergoes rapid thermal Q-switched 532 nm Nd-YAG laser is the Dermal pigmented lesions are due to a expansion, and an optical breakdown with shortest wavelength laser employed for deeper melanin in the dermis: intense shockwaves. This photomechanical pigmented disorders removal (Figures 1-2). - Blue naevi effect is crucial for Q-switched lasers It is effective for superficial epidermal - Naevus of Ota and picosecond lasers that are able to pigmentations like solar lentigines and - Naevus of Ito. disrupt the melanin and ink content freckles. The treated lesion is characterised of hyperpigmentation and tattoos by the appearance of a typical pinpoint Lasers and light-based pigment (fragmentation of intracellular pigment bleeding and a haemorrhagic crust which removal: how they work into extracellular granules subsequently lasts five to six days before falling off. The majority of lasers used in medicine, phagocytised by macrophages), as well PDL uses a rhodamine dye dissolved in a and mainly in dermatology, generate light as being a determining factor for high- solvent and pumped by a flash lamp, emits in the ultraviolet (200-400nm), visible fluence, short-pulse, pulsed dye laser a 585-600nm wavelength yellow light, near (400-760nm), near-infrared (760-1400nm), treatment of vascular disorders. In fact, the haemoglobin absorption peak, and mid-infrared (1400-3000nm) and infrared (> photomechanical damage, which clinically therefore it is considered the most specific 3000nm) wavelengths. The typical features appears with purpura, is induced by short laser currently available for the treatment of laser light are its monochromaticity, pulses and causes intravascular cavitation, of superficial vascular lesions. It is also The PMFA Journal | DECEMBER/JANUARY 2018 | VOL 5 NO 2 | www.thepmfajournal.com AESTHETIC FOCUS commonly used for treating Poikiloderma like naevus of Ota and tattoos. Patients of Civatte and really superficial pigmented usually complain of more discomfort and a lesions like solar lentigines and ephelides, prolonged downtime. since its wavelengths are absorbed by IPL technology uses a xenon broadband melanin too (Figure 3). Despite its excellent flash lamp to generate non-coherent light efficacy and safety profile, the onset of in a spectrum between visible and near purpura would limit patients’ acceptance infrared (500-1300nm). To reach the desired as it may persist for 7 to 14 days after the chromophore, filters cut the light emission laser session due to micro vaporisation of according to the wavelengths required erythrocytes, vessel rupture and subsequent by the physician; consequently, this type haemorrhage; a pressure diascopy during of light source can excite more than one the PDL session removes the blood from the chromophore (haemoglobin, melanin, vessels by closing the vessel lumen, and the water). Its versatility entails a reduced removal of vascular component of the lesion selectivity. Handpieces have a large surface avoids the purpura after the PDL session for area, generally cooled, and application of treating lentigines. gel on the skin surface is required during the Q-switched ruby laser emits a 694nm procedure. For the treatment of pigmented beam of photons, being well absorbed by lesions IPL is not comparable with melanin and minimally by haemoglobin. Q-switched lasers since its pulse duration Figure 1: It is effective for the removal of superficial in the milliseconds range make it a second A) A 49-year-old female patient with solar lentigo on the left pigmentations, lentigines, ephelides and choice. IPL employment can give excellent cheek. results when the pigmentations are matched B) The disappearance of the most part of the solar lentigo pigmented actinic keratosis as well as after only one session of Q-switched 532nm Nd:YAG laser deeper pigmented lesions, melanocytic with vascular lesions (teleangiectasias, (SYNCHRO QS4, DEKA M.E.L.A., Calenzano, Italy). naevi, naevus of Ota, naevus of Ito. erythrosis, rosacea). Q-switched alexandrite emits at 755-nm, Er:YAG laser is a solid-state laser, belonging to the near-infrared category of characterised by the presence of erbium ions lasers. At this particular wavelength the inside ytrrium-aluminum-garnet or other main chromophore is melanin, hence it is crystals; it emits photons at wavelengths mainly used for hair removal and pigmented of 2940nm, which are mainly absorbed by lesions. Since alexandrite has a similar water in the superficial layers of the skin. wavelength with ruby laser, it shares the This laser system is generally used for same pigmented indications; the longer ablating the soft and hard tissues. Its main wavelength allows a deeper effect on drawback compared to other ablative lasers dermal melanin in fact its employment gives like CO2 is its inability to coagulate. Er:YAG excellent results for nevus of Ota. laser can be used for skin resurfacing with a Picosecond alexandrite laser is a safe fractional handpiece in a minimally ablative and effective modality for the removal manner too. of pigmentary disorders. Due to its great CO2 is a gas-state laser that emits success in tattoo removal, several physicians photons at wavelengths of 10600nm. It have started to employ it for treating offers a type of ‘no-contact surgery’. In different pigmentations with promising fact, this laser system enables precise, results. Its effectiveness results from a efficacious and targeted thermal action on greater pigment fragmentation induced the lesions treated while protecting the by deep shockwaves (photomechanical surrounding tissues, thus guaranteeing effect), while its safety originates from a optimal re-epithelisation. This makes it reduced and selective thermal damage suitable for surgical procedures since the