Key points
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Overview of tattooing history, technique and inks.
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Overview of lasers used for tattoo removal.
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Patient selection for laser tattoo removal.
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Laser technique for tattoo removal.
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Complications and side-effects of laser tattoo removal.
Tattoo history
Tattoos have been a part of popular culture for thousands of years. Early tattoos have been identified in Egyptian mummies over 2000 years ago. The tattoos were commonly linear and dot patterns, found mainly on women, and thought to be related to religious rituals. The earliest human tattoos were identified on the corpse of Otzi the Iceman, a 5000 year-old natural mummy found in the Otzal Alps in Northern Italy. He had 57 tattoos that were placed for what seems to be medicinal reasons.
Starting as early as 300 bc some men in Japanese and Chinese society tattooed their faces to protect themselves from evil forces. By 300 ad , prisoners and thieves were identified by tattoos, relegating tattoos to common criminals within Asian society. Western Europeans popularized tattooing in the 18th century with many of elite society placing discreet tattoos on their body. It was thought that tattooing was popularized in Europe by British sailors returning home with tattoos placed while sailing in Southeast Asia and interacting with heavily tattooed locals.
In modern Western society, tattoos were re-popularized during World War II with many veterans proudly displaying their service commitment. In the 1950s tattoos became popular with bikers and criminals. Tattoos were thought to be a strong anti-establishment statement. In the 1960s and 1970s, tattoos continued to be popular symbols of rebellion and non-conformity and were commonly seen on musicians and hippies. Gang members often tattoo themselves to assert membership with a specific gang organization. These tattoos are often prominently placed on the hands and face to flagrantly state their anti-establishment culture. More so, gang members may tattoo themselves with symbols that have specific meaning such as having served time in prison or murdered someone.
Recently, tattoos have become far more accepted within mainstream culture. It is estimated that approximately one out of 20 individuals in Western society has a tattoo. This number is closer to one out of nine in the United States. Several recent studies reflect that between 10 and 35% of young Americans ages 12–35 have been tattooed. Individuals within mainstream society elect to be tattooed for reasons including social acceptance with friends and acquaintances who are being tattooed. Some will be tattooed as a form of self-identity, decoration, or organization membership (sports teams, fraternities, sororities). Tattoos have become so mainstream in popular culture that some would say that to be unique, different and special in today’s tattoo culture would be not to follow current fashion trends and instead keep your body tattoo free.
Unfortunately, the social rationales for getting tattooed often become irrelevant with time and ultimately many tattooed individuals desire to remove their body-art. Non-laser alternatives for tattoo removal include dermabrasion, salabrasion, and surgical removal. Each of these procedures is likely to leave scarred remnant skin and unacceptable cosmetic results. Historically, laser alternatives for tattoo removal have included laser resurfacing with a CO 2 or erbium-yag laser. Unfortunately, ablative lasers are also likely to leave unreasonable scarring and hypopigmention and are not routinely used for tattoo removal. Fortunately, high energy Q-switched lasers have high efficacy with lower risk of scarring and hypopigmentation, and have become the ‘gold standard’ for laser tattoo removal.
Modern tattooing methods
Tattoo placement at its most basic level consists of introducing ink into the dermal level of the skin. This is most commonly accomplished by dipping or coating a solid needle in ink and then piercing the skin to deposit the ink. Amateur tattoos are often administered by depositing India ink, charcoal ink, or other more unconventional inks into the skin using sewing needles or other sharp objects. Generally, the sharp needle is wrapped in ink soaked thread and repeatedly punctured through the skin to produce the pattern of interest. This is a simple and common way to perform tattoos in prisons and in casual social settings. This poorly hygienic method of tattoo application places the recipient at a high risk of infection including blood-borne pathogens such as hepatitis, tetanus and HIV, as well as local infection with Staphylococcus aureus , herpes simplex and deep fungal pathogens.
Professional tattoos are performed in tattoo parlors which are required to follow specific regulations within their jurisdiction. Universal precautions for bloodborne pathogens, including biohazard containers for sharps, single use disposable gloves, a clean field for tattoo placement, and sterile needle packages should be expected at any reputable tattoo parlor. The tattoo is stenciled onto the skin and the tattoo ink is ultimately applied using an electric tattoo gun with sterile disposable needles and fresh ink. Modern professional tattoo systems consist of electric powered tattoo guns that hold between 1–14 disposable needles that oscillate between the skin and a disposable ink dispenser. These needles can penetrate the skin 1–30 times per second, depositing ink particles at a dermal depth of 1–2 mm in depth.
The ink particles are 140–180 nm in diameter, rendering them too large for clearance by the reticulo-endothelial system. The particles are ultimately encapsulated by macrophages and remain within the dermal collagen matrix until fractured by high energy laser therapy.
Tattoo inks
The overall effectiveness of laser tattoo removal is dependent on the wavelength of the laser light used and the color of the ink with which the light wavelength is interacting. The most common color ink used in tattooing is black followed by red, blue, green, and yellow. Table 9.1 presents an overview of primary ink colors and composition. Many different dyes are used in modern tattoo placement: carbon black, titanium dioxide, iron oxide, azo dyes, as well as acridine phthalocyanine, naphthol, and quinolone substrates. Newer tattoo inks include plastic based inks such as acrylonitrile butadiene styrene (ABS plastic) inks. Historically, the chemical dyes and pigments could be removed effectively with the appropriate wavelength of laser light. With the advent of so many different ink types, complete removal of tattoo ink can be a difficult task.
| Pigment color | Composition |
|---|---|
| Black | Carbon black Iron oxide |
| Red | Cinnabar Mercury Cadmium Iron oxide Napthol-AS |
| Blue | Phthalocyanine blue Cobalt Azurite |
| Green | Phthalocyanine green Chromium oxide Lead chromate Ferrocyanides |
| Yellow | Chrome yellow Cadmium |
| Flesh | Iron oxide |
| White | Titanium White lead Zinc |
Many reputable tattoo parlors procure their ink from established manufacturers that are required by the FDA to produce an id number and a MSDS sheet for each ink that their facility produces. Many of these companies produce 50–60 different ink colors. The ability to successfully remove these inks is often dependent on the composition of these inks.
Titanium is used for white inks and to lighten and brighten numerous different colors. In a personal review of 59 inks produced by one manufacturer, 43 of ink colors (72.8%) contained titanium, an element known to make the ink resistant to tattoo removal. Titanium will undergo oxidative–reduction changes when treated with Q-switched laser causing a grayish discoloration that may fade slowly with subsequent treatments or may persist after numerous laser sessions. Flesh tone inks present a similar challenge in that these inks contain iron oxide which darkens into a greenish hue upon interaction with laser light. Laser providers must be aware of these risks when assessing the removal of cosmetic tattoos including permanent eyeliner, lip liner, and areola tattooing following breast surgery.
In addition to standard commercial tattoo inks, many tattoo artists custom mix inks making it impossible to identify the ink’s true composition. A survey by the FDA has shown that over 50 different compounds are currently used in tattoo inks. Of these inks, several are not indicated for placement on human skin much less injected into human skin. There are reports of unconventional inks such as industrial printer inks and car paint use in the tattoo industry. Additionally, heavy metals such as mercury, lead, and arsenic have been identified in tattoo ink. The latest advancements in tattoo inks involve the production of microencapsulated, biodegradable and bioabsorbable dyes within colorless polymer beads. These ink beads are injected into the dermis using similar techniques as are used for injecting conventional tattoo ink. The ink particles will persist until the spherules are ruptured by a single laser treatment.
Lasers used in tattoo removal
The goal of laser tattoo removal is to destroy unwanted tattoo ink while leaving the surrounding skin undamaged. Historically, argon, CO 2 , and erbium-Yag lasers have been used for tattoo removal. These lasers successfully removed tattoo ink through epidermal ablation and ink destruction followed by eventual re-epithelialization; however, a significant proportion of treated patients were left with residual scarring. These side-effects proved these systems inadequate for routine tattoo removal. As early as the 1960s, the Q-switched ruby laser successfully destroyed melanocytic pigment and exogenous tattoos without scarring. Modern Q-switched lasers are able to produce high energy output in short bursts within the nanosecond range. A Q-switched laser is generally a solid state laser that can produce high energy pulses by modulating intracavity losses – this is measured by the strength of the damping of the oscillations of emitted light wave (Q-factor). The energy produced is accumulating but is not released, the resonator losses are suddenly reduced creating a rapid buildup of power which is ultimately released as a short burst high energy laser pulse.
These bursts of light energy thermally and photoacoustically destroy the target chromophore (tattoo ink), but do not heat the surrounding tissue enough to damage it. This light/tissue interaction is based on the theory of selective photothermolysis. The wavelength of laser energy matches the absorption spectrum of the target and the burst of energy destroys the intended target without heating the surrounding tissue to the point of damage. It is postulated that the tattoo ink is fractured into particles that are small enough for macrophage phagocytosis and clearing through lymphatic channels as well as trans-epidermal elimination. Current Q-switched lasers include Q-switched ruby, alexandrite and Nd:YAG. Each laser has unique wavelengths and properties that will determine which ink colors it can treat ( Table 9.2 ). Q-switched ruby laser 694 nm is indicated for black, blue, and green ink. The Q-switched Nd:Yag 532 is ideal for resolving red ink and 1064 (infrared) is indicated for black ink. Q-switched alexandrite 755 nm is indicated for light blue and green ink.
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