Tattoos date back to Neolithic times, and have been used for identification, decoration, spiritual reasons, medical purposes, and cosmesis.

Interest in tattoos has surged in recent years, with more than 10 million people in the United States and over 20 million to 30 million in the Western world having at least one tattoo.1,2

Tattoos are exogenous pigments that are placed in the dermis. Multiple pigments are used for the coloring of tattoos (Table 1) and the quality of the inks can vary widely. Professional tattoo artists use refined inks that fade less over time and are more difficult to eliminate with laser therapy.

TABLE 1

Color

Pigments


Black

Carbon

Iron oxide

Logwood (extract from logwood tree)

Blue

Cobaltic aluminate (azure blue)

Green

Chrome oxide (Casalis green)

Hydrated chromium sesquioxide (Guignet’s green)

Malachite green

Lead chromate

Ferro-ferric cyanide

Curcumin green

Phthalocyamine dyes (copper salts with yellow coal tar dyes)

Red

Mercury sulfide (cinnabar)

Cadmium selenide (cadmium red)

Sienna (ochre-ferric hydrate and ferric sulfate)

Yellow

Cadmium sulfide (cadmium yellow)

Ochre

Violet

Manganese violet

White

Titanium dioxide

Zinc oxide

Flesh

Iron oxides (a variant of color)

In addition, each ink has unique absorption coefficients and, therefore, variable responses to different laser wavelengths. Certain pigments are more prone to have adverse reactions, either independently or secondary to laser therapy.

TATTOO TYPES

Tattoos may be categorized into several types: amateur, professional, medical, cosmetic, and traumatic. The distinct qualities of each type of tattoo dictate the behavior and varying responses to laser therapy.

Amateur tattoos are typically small and done in black or blue-black ink. They are composed of lower-quality inks, which tend to fade more rapidly than inks in other types of tattoos.

The pigment used is most commonly India ink or another carbon material, with ink particles that are large and found at various depths throughout the dermis. Amateur tattoos are easier to remove than professional tattoos, with 80% of amateur tattoos clearing after four to eight treatments.3

Professional tattoos use higher-quality inks that last longer, contain more vibrant colors, and respond less well to laser treatment. Greater quantities and densities of pigment are used, making complete clearing a bigger challenge.

The presence of multiple pigments in one tattoo is commonplace (Figure 1). There is a narrow depth and more uniform range of particles in the dermis, typically at 0.5 mm. Sixty-five percent of professional tattoos clear after six to eight treatments.3 Successful treatment depends on the color of the tattoo, the pigments that comprise that color, and the type of laser used.

Figure 1. Vibrantly colored professional tattoo.

Cosmetic tattoos are becoming in­creasingly popular as “permanent makeup.” These tattoos are most common on the lips, eyelids, and eyebrows, and on the breasts following surgical reconstruction. Due to the structure of some flesh-colored and pink pigments, cosmetic tattoos can be very difficult to eliminate and may require 15 to 20 treatments.

Trauma also may be a source of tattooing. Traumatic tattoos are acquired via innumerable ways from childhood through adulthood. The desire for removal is proportionally higher as these tattoos are typically on exposed areas and involuntarily acquired.

Multiple injuries or blast by-products can create traumatic tattoos, such as graphite, shrapnel, and gunpowder. The pigment, which is often carbon-based, is typically more superficial in the dermis and usually responds very well to treatment (Figure 2a and 2b, below.)

Radiation port tattoos, particularly in the breast area of women, respond quite well to treatment.

Figure 2a. Traumatic tattoo resulting from blast of improvised explosive device in Iraq. Figure 2b. Traumatic tattoo after two treatments with the Q-switched 1064 nm Nd:YAG.
(Courtesy of Nathan Uebelhoer, DO)

REMOVING TATTOOS

In a random survey analysis of 500 subjects between the ages of 18 and 50, 24% had at least one tattoo, and of those, 17% were considering removal.4

People seek tattoo removal in order to improve self-esteem; for a change of mind or perspective; as well as for domestic or familial reasons, social factors, and employment purposes.5

Many people acquire tattoos when they are young, may have obtained them impulsively and inexpensively, and then regretted it for decades. In other cases, tattoos may cause psychological, social, and financial strains.5 Cosmetic tattoos are often removed for misplacement or migration of pigment, allergic reactions, or other dissatisfactions.6

Multiple strategies can be used for the removal of tattoos. These procedures include dermabrasion, salt dermabrasion, excision, and tangential excision with a dermatome—all are associated with a considerable risk of scarring.7

Laser therapy is now the gold standard for tattoo removal, and revolves around the theory of selective photothermolysis. This theory states that by choosing the appropriate optical radiation, one can selectively target and damage the desired chromophore while minimizing any surrounding collateral damage.

Tattoo inks are exogenous chromophores in the skin. Light energy from lasers is rapidly absorbed into the chromophores with an abrupt deposition of energy, creating photoacoustic fragmentation of the tattoo particles.8 The fragmented tattoo particles are phagocytosed for removal by lymphatic drainage.1

The various colors in tattoos absorb different wavelengths of light; therefore, they need to be treated with lasers that deliver at these different wavelengths. The absorption coefficient of a chromophore is the extent to which it absorbs a specific wavelength of light, or energy. Selecting the wavelength with the greatest absorption coefficient allows the greatest absorption of this optimal energy.

The use of quality-switched (“Q-switched”) lasers optimizes the selective photothermolysis of tattoo inks. Q-switched lasers deliver energy in a matter of nanoseconds, whereas non-Q-switched lasers deliver the energy at a much slower rate.

By delivering the energy over an abbreviated time with Q-switched lasers, the heat does not have time to diffuse to the surrounding tissue and cause unnecessary collateral damage. The ink particles are heated so abruptly that focal thermal and photoacoustic damage is confined solely to the tattoo.

There are four primary Q-switched lasers, each with advantages. The first developed Q-switched laser, the Q-switched Ruby, has a wavelength of 694 nm. The Q-switched Neodymium: Yttrium-Aluminum-Garnet (Nd:YAG), 1064 nm, and the Q-switched Frequency-Doubled Nd:YAG, 532 nm, came later, followed by the Q-switched Alexandrite, 755 nm.1 Some tattoos require a combination of lasers to achieve optimal results.

The laser selection for tattoo removal correlates with the peak absorption for the ink color in the tattoo. Black is good at absorbing all wavelengths of light (Figure 3a and 3b).

Figure 3a. Black professional tattoo pre-treatment. Figure 3b. Black professional tattoo following six treatments with the Q-switched Ruby.

The other colors have more specific ranges of absorption, and optimal treatment is associated with certain wavelengths. For example, green has maximal light absorption of 630 nm to 740 nm, making ruby the best countermeasure.9,10 Red has maximal absorption from 505 nm to 560 nm, making the 532 nm Q-switched Frequency-Doubled Nd:YAG optimal (Table 2).

Table 2


Color of Ink

532nm

694nm

755nm

1064nm


Black-amateur

very good

excellent

excellent

excellent

Black-professional

very good

excellent

very good

excellent

Blue/Black

very good

excellent

excellent

excellent

Blue

good

very good

excellent

good

Green

good

excellent

very good

fair

Brown

fair

good

good

fair

Red

excellent

poor

poor

poor

Purple

good

fair

fair

good

Orange

good

fair

fair

good

Yellow

poor

poor

poor

poor

Tan

good

poor

poor

poor

No single laser system is capable of treating all tattoos, and each system comes with unique advantages.

For example, the 1064-nm Nd:YAG features relatively low absorption by melanin, making it the safest laser to use with darkly pigmented patients, minimizing the risk of hypo- or hyper-pigmentation or scarring.10

TATTOO REMOVAL CHECKLIST

  • No laser system can adequately manage all tattoos.
  • Knowledge of tattoo types, pigments, and laser-tissue interaction is imperative for successful treatment.
  • Establishing realistic goals given available technology is of the utmost importance.
  • As most tattoos cannot be completely removed, a goal of 75% clearing is realistic with professional tattoos.

The longer the wavelength the greater the depth of penetration, which also makes the 1064-nm Nd:YAG laser a better choice for treating deep-seated dermal pigmentation.

The age and location of tattoos also can affect the patient’s response to laser therapy. Older tattoos tend to respond more favorably, likely due to the decreased density of pigment from its natural migration.11 Tattoos on the distal extremities are more difficult to treat, presumably due to decreased lymphatic drainage of phagocytosed pigment.11

The strategy for tattoo removal is three-pronged:

  1. Identify the chromophores;
  2. Select the appropriate Q-switched laser, or lasers, to optimally target the chromophores; and,
  3. Deliver the minimal energy necessary to cause thermal damage confined specifically to the tattoo, with no collateral damage.

The clinical end point to treatment is immediate, superficial whitening corresponding to tissue water vaporization from thermal damage.1 There may be mild pinpoint bleeding.

Local anesthesia is often needed to make the procedure tolerable—intratattoo lidocaine is most commonly used. Other anesthetic options include topical anesthesia, cryogen air cooling (eg, Zimmer, MedizinSystems), and cooling with the Palomar CoolRoller.

Following laser therapy, a hydro-occlusive dressing or ointment with nonadhesive dressing should be used until re-epithelialization occurs.

ADVERSE EVENTS

Although the implementation of Q-switched lasers has greatly enhanced the safety and efficacy of tattoo removal, associated adverse reactions still exist.

The biggest risk is scarring. To minimize this risk, it is crucial to use the appropriate Q-switched laser for the patient’s skin type and tattoo colors, combined with the lowest fluence to achieve the clinical endpoint.

Non-Q-switched lasers will likely cause scarring due to excessive thermal diffusion of the energy, leading to damage of surrounding collagen.

A cobblestone texture of the skin may be seen within the first 2 weeks following laser therapy. This may be a predictor of incipient scarring. Class 1 topical corticosteroids applied twice daily may counter the risk and resolve the problem.1

Figure 4. Oxidation of an aesthetic lip liner tattoo.

Tattoo pigment blackening is a common adverse response seen with white, pink, flesh-colored, and some red and yellow tattoos (Figure 4).2

Blackening of the pigments results when inks containing ferric oxide are heated and reduced to ferrous oxide, which is black.6 Titanium dioxide in some tattoos also may be reduced to black pigmentation,1 as is also the case with gold. In addition to blackening, the presence of titanium dioxide in tattoos has been associated with a poor response to laser therapy.12

Patients should be counseled on the risk of potential darkening of the tattoo. Ideally, the exact pigments used by the tattoo artist should be ascertained. If darkening of the tattoo occurs, multiple additional Q-switched laser treatments may successfully eliminate the pigment.13 Alternatively, laser ablation or excision may be used in select cases.1

Allergic reactions can be stimulated or exacerbated by laser therapy.14,15 Allergic reactions to tattoos have increased correspondingly with the overall increase in tattoos.16 Use of intralesional corticosteroids often mitigates the problem.16

Delayed hypersensitivity reactions to tattoos days to weeks after laser therapy can occur, as antigenic pigment is fragmented and released from the immunologic confinement of the tattoo granuloma, and exposed to the immune system14.

Immediate hypersensitivity reactions with intense urticaria within 30 minutes of treatment have been reported.14 Pre­medicating the patient with systemic corticosteroids and antihistamines may prevent subsequent episodes,14 but treating such patients is still risky. In this in­stance, use of an ablative laser or other surgical approach is often the best option.

Extreme caution should be employed when managing a patient with a systemic allergic response to laser therapy.1

Dispigmentation can occur after any laser therapy if the normal endogenous pig­mentation is damaged. Temporary hypo- or hyper-pigmentation—or even per­manent hypopigmentation—can occur.

Great caution should be used when lasering individuals with darker skin types. The 1064-nm Nd:YAG is the safest laser for treating tattoos in dark skin, as it has low melanin absorption.

THE FUTURE OF TATTOO REMOVAL

Tattoos continue to gain in popularity, as does the demand for high-quality tattoos that do not fade and will maintain vibrant colors—all of which means the tattoo of the future may be more difficult to remove.

New research is focused on developing lasers with picosecond pulse durations for clearing more vibrant pigments.15 The optimal pulse duration for fragmenting tattoo particles is 10 picoseconds to 100 pico­seconds.8 Given equal energy, a shorter pulse duration can offer a more efficient treatment, minimizing fluence and collateral damage.8

See also “Lasers to the Rescue” by Michelle Ehrlich, MD, in the March 2006 issue of PSP.

Currently, only prototypes of picosecond lasers are available. Trials have been promising, with higher success rates for clearing tattoos using fewer treatments.17,18

New tattoos are being developed that may be easier to remove. For example, to remove magnetite (Fe3O4) tattoos, begin with Q-switched laser therapy and then use external magnets to extract fragmented pigments via the disrupted epithelium.19

New microencapsulated biodegradable and bioabsorbable inks are being developed to facilitate tattoo removal. The biodegradable pigment is encapsulated in a microsphere. The spheres are injected into the upper dermis. The laser heats the biodegradable pigments, which lyses the capsule with a single treatment. After that, the body resorbs the pigments.20


Eric C. Parlette, MD, practices dermatology in San Diego. Parlette graduated from the University of Virginia School of Medicine. He can be reached at [email protected]

Michael S. Kaminer, MD, is a former assistant professor of dermatology at Harvard Medical School, and is currently assistant clinical professor of dermatology, Section of Dermatologic Surgery and Oncology, Yale Medical School, and adjunct assistant professor of medicine (dermatology) at Dartmouth Medical School. He can be reached at [email protected]

Kenneth A. Arndt, MD, is clinical pro­fessor, Section of Dermatologic Surgery and Cutaneous Oncology, Yale University School of Medicine; adjunct professor of medicine (dermatology) at Dartmouth Medical School; and clinical professor of derma­tology, Harvard Medical School. He can be reached at [email protected]