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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 content in the thus minimising the damage to surrounding cell proliferation and migration, modulation 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 target tissue absorbs. and increased healing of wounds. • 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 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 skin: photomechanical, photothermal and 1200nm), as well as nonselective lasers, • 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 . The treated lesion is characterised of hyperpigmentation and by the appearance of a typical pinpoint Lasers and light-based pigment (fragmentation of intracellular pigment bleeding and a haemorrhagic 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 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 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, ). 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 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 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 (photothermal effect). As it targets the limited inflammatory response is conducive pigment through shorter picosecond pulses to better healing. The extreme precision of this kind of laser has the ability to achieve the application means that the epidermis the same results as a Q-switched laser but alone can be vaporised, or the thermal through less sessions. The reduction of the effect can be extended even deeper into number of laser sessions implies a shorter the papillary or reticular derma. The use of post-treatment downtime for the patients, ‘colour indicators’ allows for step-by-step who are able to better tolerate all the visual assessment of the level reached and procedures. an accurate calculation of the clinical ‘end- Q-switched 1064nm Nd-YAG laser point’ phase. Ablative resurfacing with CO2 produces light in the infrared part of the laser has been considered the -standard spectrum at a wavelength of 1064nm. for many years in the treatment of wrinkles, Melanin does not absorb this wavelength and skin damage from photoageing. These skin resurfacing lasers (Er:YAG and CO2) Figure 2: well, and for this reason the 1064nm Nd:YAG A) The typical brownish of the hands in a 63-year-old laser is not considered optimal for the can be employed for removing superficial patient. removal of pigmented lesions. Its advantage pigmented lesions like lentigo simplex, B) The post-procedure erythema on the areas treated by results from the capability to penetrate solar lentigo, seborrheic keratoses, and Q-switched 532nm Nd:YAG laser (SYNCHRO QS4, DEKA M.E.L.A., Calenzano, Italy). deeper into the skin, up to 5-7mm; therefore dermatosis papulosa nigra. C) The results achieved after one session. its indications are deep pigmented disorders Fractional CO2 laser is equipped

The PMFA Journal | DECEMBER/JANUARY 2018 | VOL 5 NO 2 | www.thepmfajournal.com AESTHETIC FOCUS

A) Therapeutic steps unit area, and it is inversely proportional to the fraction of light absorbed by the target 1. Clinical features chromophore. Increased fluence must be The main features to be evaluated are the used with chromophore-poor targets, deep skin phototypes. Racial genetics play a skin targets and targets which barely absorb significant role in determining a patient’s the wavelength. At the beginning of the response to any skin laser treatment. first treatment session the dermatologist Contrary to traditional skin classifications should choose the fluence according to the (the six Fitzpatrick types), the new genetic- patient’s pain threshold and in view of the racial classification takes into consideration clinical endpoint of that particular laser in the racial origins of patients rather than use. The last parameter to be selected is the their skin colour alone. Indo-Pakistani, pulse duration, which is determined by the B) African and Asian, Aboriginal and Mixed thermal relaxation time (TRT) of the target, race patients have a higher tendency that is, the time the tissue takes to lose half to develop hypo and above all post- the acquired heat which is proportional inflammatory hyperpigmentation (PIH) to the square of the target’s diameter; the than European, Nordic and Mediterranean. TRT of a larger structure will be longer than The treatment of these high-risk candidates the TRT of a smaller structure. The pulse requires management by expert hands, the duration must be shorter than or equal to correct instruments and within the proper the TRT in order to limit the damage to the parameters (Table 1) [9-13]. Nowadays, the target tissue. If the duration is too short knowledge of the patient’s racial origin, and it could imply a loss of efficacy, whereas if that of parents and grandparents, should the pulse is longer than the TRT the heat Figure 3: always be matched with a detailed ‘skin will spread to the surrounding structures, A) a 44-years-old female patient with a diffuse B) remarkable improvement after two sessions of Fractional imaging report’ to determine appropriate with the risk of possible scarring and other CO2 laser (SmartXide2 DOT/RF, DEKA M.E.L.A., Calenzano, laser treatment modalities. High texture changes. Italy) performance 3D imaging systems provide life-like high quality 3D reconstruction 3. Performing the procedure images (such as 3D LifeViz®, Quantificare, Before beginning with the laser session, Valbonne, France). These systems include it is very important to document a with a scanning system which makes an image management software with complete medical history of the patient, it possible to obtain vertical micro- superior photo documentation capabilities to identify any possible contraindications. columns of damage, micro-ablative to visualise, analyse and archive 3D images. There may be a reason that the patient and micro-thermal zones (MAZs and With the 3D analysis module, users can cannot be treated (Table 2). A detailed MTZs), surrounded by areas of healthy detect and precisely quantify subtle photo documentation prior to each laser tissue. Depending on the pulse used, features quickly and easily. procedure is necessary for showing the the controlled release of heat in the results achieved and for potential legal treated micro-areas has an immediate 2. Selection of the parameters medical issues. The patients should tissue-shrinking effect and generates the Once the correct laser has been selected, always be informed about the practical stimulation of growth factors, wound the physician must decide on the aspects of the session, giving them realistic repair, and the reorganisation of new most appropriate parameters, such as expectations about the results. Moreover, collagen (Figure 4). Another feature which wavelength, spot size, fluence and pulse they should receive written information increases the versatility of this application duration. The wavelength has to be chosen about possible side- effects and post- is the possibility of selecting the distance by considering the main chromophore procedure woundcare. The physician must (DOT spacing) between surrounding inside the lesion, as well as its light always begin with a test on a small part of MAZs and MTZs, providing a resurfacing absorption peak and depth. A Q-switched the pigmented lesion, and continue the full effect similar to the ablative technique laser at 532nm is able to remove the treatment only if it is safe and effective. with reduced spacing, or the more typical superficial pigment of a brownish lentigo, In our opinion melanocytic lesions should fractional effect, with greater spacing whereas only if used at 1064nm can it not be treated, since these treatments between DOTs. Each treatment session remove black tattoo ink. The spot size could impede or delay the correct diagnosis consists of numerous successive and should match the diameter of the target of malignancy; also the histological consecutive pulses [1-5] in the same point structure as closely as possible to minimise examination through a biopsy may not without moving the scanner (‘scalpel damage to the surrounding tissues. The be enough to exclude an early malignant effect’). fluence can be considered as the energy per pigmented lesion. During the treatment,

Table 1: Suggestions for darker skin types. Wavelength Longer wavelength (less epidermal absorption) Sessions Higher number of sessions Parameters Lower fluence Longer pulse time Cooling During and after the session for reducing the thermal injury Post-treatment topical care Topical corticosteroids for reducing temporary side-effects Complete sun protection (SPF≥50)

The PMFA Journal | DECEMBER/JANUARY 2018 | VOL 5 NO 2 | www.thepmfajournal.com AESTHETIC FOCUS

Table 2: Contraindications to laser / light pigment removal.

Extreme tan Laser sessions should be delayed until the loss of the tanning

Endocrine abnormalities May make laser / light based treatments less effective

Pregnancy No evidence of possible risks, but the treatment is not recommended due to potential legal issues

Autoimmune connective diseases High photosensitivity

Dermatological disorders with Koebner phenomenon , and may be triggered by a laser / light employment

History of hypertrophic scars and Laser / light sessions can cause impaired tissue repair and subsequently scars and keloids

Gold intake Can cause with cutaneous diffuse hyperpigmentations

Isotretinoin 6-12 months of washout time after oral isotretinoin, otherwise there are risks of skin fragility, delay in reepithelisation, hyperpigmentations and scars

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The PMFA Journal | DECEMBER/JANUARY 2018 | VOL 5 NO 2 | www.thepmfajournal.com