Overview

Since the beginnings of modern civilization, tattoos have existed and have been used as a form of self expression. Their popularity has exploded in recent times, with 1 in 4 Americans having at least 1 tattoo; the corollary to this is an even greater interest in removal, with an estimated 17% of those with a tattoo considering removal. The latest techniques and methods for tattoo removal use Q-switched laser technology.

Complete tattoo removal requires lasers of differing wavelengths to remove all the available ink colors. Tattoo ink resides in the epidermal/dermal interface of the skin. Therefore, appropriate laser wavelength and fluence selection is critical, to allow targeting of ink particles without damaging surrounding skin. The concept of selective photothermolysis, or the preferential targeting of specific chromophores, makes this possible. There are 5 general types of tattoos: amateur, professional, cosmetic, medical, and traumatic. This article aims to reveal the latest techniques and advances in laser removal of both amateur and professional tattoos, as well as cosmetic tattoos and permanent makeup. Each of these pose different challenges to the removing physician, but the goal is always the same: removal without sequelae.

Perspective on tattooing

Tattooing dates back to as early as 12,000 bc, when ash was rubbed into skin incisions. As the techniques of tattooing evolved, puncturing the skin with ink needles became popular because it can create precise patterns and colors. Tattoo removal is probably as ancient as the invention of tattooing itself. The earliest documentation of tattoo removal was by Aetius, a Greek physician who described salabrasion in 543 ad .

Historically sulfuric acid, nitric acid, tannic acid, lye, turpentine, garlic, salt, pepper, vinegar, lemon juice, human milk, goat milk, cantharides, decomposed urine, and excrement of pigeon are just some of the many substances once used for tattoo removal. Traditional destructive methods such as dermabrasion or simple surgical excision with skin grafting have been used, but with the resultant unsightly scar. Argon or CO ₂ laser vaporization is still used today but it, too, has a high risk of scarring. The ideal technique should remove all the pigment deposited in the skin layers, leaving little or no scar.

In 1965 Leon Goldman reported the first laser tattoo removal. Then in 1967 he used a Q-switched ruby laser (QSRL) for successful laser tattoo removal with minimal scarring. Subsequent laser techniques were further improved based on the theory of selective photothermolysis introduced by Anderson and Parrish. Because modern tattoos contain a myriad of ink colors, a variety of laser wavelengths are necessary to match the absorption spectrum. Modern laser systems now use these 4 laser wavelengths for tattoo removal: frequency-doubled Nd:YAG (532 nm), high-energy Q-switched ruby (694 nm), alexandrite (755 nm), and Nd:YAG (1064 nm), which emits electromagnetic radiation pulses of 10- to 100-nanosecond duration.

Perspective on tattooing

Tattooing dates back to as early as 12,000 bc, when ash was rubbed into skin incisions. As the techniques of tattooing evolved, puncturing the skin with ink needles became popular because it can create precise patterns and colors. Tattoo removal is probably as ancient as the invention of tattooing itself. The earliest documentation of tattoo removal was by Aetius, a Greek physician who described salabrasion in 543 ad .

Historically sulfuric acid, nitric acid, tannic acid, lye, turpentine, garlic, salt, pepper, vinegar, lemon juice, human milk, goat milk, cantharides, decomposed urine, and excrement of pigeon are just some of the many substances once used for tattoo removal. Traditional destructive methods such as dermabrasion or simple surgical excision with skin grafting have been used, but with the resultant unsightly scar. Argon or CO ₂ laser vaporization is still used today but it, too, has a high risk of scarring. The ideal technique should remove all the pigment deposited in the skin layers, leaving little or no scar.

In 1965 Leon Goldman reported the first laser tattoo removal. Then in 1967 he used a Q-switched ruby laser (QSRL) for successful laser tattoo removal with minimal scarring. Subsequent laser techniques were further improved based on the theory of selective photothermolysis introduced by Anderson and Parrish. Because modern tattoos contain a myriad of ink colors, a variety of laser wavelengths are necessary to match the absorption spectrum. Modern laser systems now use these 4 laser wavelengths for tattoo removal: frequency-doubled Nd:YAG (532 nm), high-energy Q-switched ruby (694 nm), alexandrite (755 nm), and Nd:YAG (1064 nm), which emits electromagnetic radiation pulses of 10- to 100-nanosecond duration.

Principles of laser tattoo removal: selective photothermolysis

Laser tattoo/permanent makeup removal cannot be discussed effectively without understanding the principles of selective photothermolysis.

Chromophores

Tattoo ink particles absorb and reflect light of a certain wavelength, thus giving them a characteristic color. These particles are considered chromophores in the dermis, which compete with other native chromophores. In the skin, there are 3 main chromophores: (1) melanin, (2) hemoglobin, and (3) water ( Fig. 1 ). It is possible to target a specific chromophore by selecting a wavelength that is absorbed by it, with minimal absorption by other competing chromophores. When laser of a specific wavelength effectively matches the maximum absorption spectra of the chromophore, energy is absorbed and heat is produced within the tissue. The ink particles absorb specific laser wavelengths and are disintegrated in the tissue as a result of the same process. A sufficient heat-energy threshold must be obtained to produce the desired clinical effect.

The three main chromophores in the skin.

( From Nelson AA, Lask GP. Principles and practice of cutaneous laser and light therapy. Clin Plast Surg 2011;38:428; with permission.)

In vivo mechanisms, consequences, and appearance of tattoo particle clearance

Tattoo ink is usually located within the epidermal/dermal junction and/or deeper into the dermis. Extracellular tattoo ink particles absorb the laser energy and disintegrate in the tissue matrix. Intracellular tattoo ink particles are found within dermal fibroblasts and mast cells, predominantly in a perivascular location. Modern Q-switched lasers cause :

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  Selective rupture of these cells

  
  
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  Breakdown of tattoo ink particles

  
  
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  Ink removal by phagocytosis, transepidermal elimination, and/or lymphatic transport.

The tattoo ink may still remain inside the body, either permanently taken up in regional lymph nodes or as a lightened, residual tattoo in the skin with resultant textural changes.

Once in the lymph node, the tattoo particles usually reside without pathologic sequelae; however, this particulate matter may represent an immunogenic or antigenic stimulus in an already inflammatory milieu, leading to immune activation or resultant lymphadenopathy. The exact mechanism of such immunoreactivity most likely involves the migration of laser-induced pigment microparticles to regional lymph nodes or an acute inflammatory process following the trauma of laser-skin and laser-pigment interaction. These liberated tattoo inks travel out of the skin, a process facilitated by the influx of antigen-presenting cells and phagocytes, and by the increased vascular permeability of the inflamed tissue.

A recent case report documented the potential for laser tattoo removal to cause a systemic infectious disease reaction in an untreated tattoo of the same individual via immunologic sensitization caused by the exposure to the ink compound ( Fig. 2 ), a hitherto unknown complication of laser tattoo removal therapy.

( A ) A right ventral wrist tattoo that was treated with laser. ( B ) The patient’s right dorsal foot. The patient developed a distant reaction at this untreated tattoo site.

([ A ] From Harper J, Losch AE, Otto SG, et al. New insight into the pathophysiology of tattoo reactions following laser tattoo removal. Plast Reconstr Surg 2010;126(6):314e; with permission.)

The appearance of lightened tattoo may be the result of the intrinsic optical properties of smaller tattoo particles. The tattoo particles are still present but are too small (with diameters smaller than 10 nm) to be visibly appreciable by the human eye, evident from computer simulation of laser-tattoo interactions, which demonstrate that breakup of tattoo particles is photoacoustic. Simulation studies using clinical parameters demonstrate that the tensile stress generated inside tattoo/graphite particles is strong enough to cause material fracture. The smallest tattoo particles are more difficult to break up because the strength of the tensile stress decreases with particle size; fortunately, smaller particles are less visible.

Immediately after laser treatment the targeted pigment turns white, likely corresponding to dispersion and destruction of the pigment particles as the result of the heat. Adjacent tissue can be damaged as the heat causes expansion and creation of a cavitation bubble that surrounds the tattoo particle; the bubbles are likely the cause of the empty vacuoles in the ash-white lesions seen throughout the dermis after treatment. The resultant heat also generates steam, which permeates into cracked particles and induces steam-carbon reactions causing the tattoo particles to become grossly transparent.

Clinical algorithm of laser tattoo removal

In their clinical practice the authors use a Q-switched laser with 3 laser frequencies:

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  Frequency-doubled Nd:YAG (532 nm)

  
  
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  Alexandrite (755 nm)

  
  
• 3.
  

  Nd:YAG (1064 nm) (Versapulse Select, Coherent, Palo Alto, CA, USA).

In addition, a Zimmer Cryo5 Chiller (Zimmer Elektromedizin, Irvine, CA, USA) is used for skin comfort during the laser operation. The number of laser treatments required for tattoo removal depends on the:

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  Color and type of tattoo ink

  
  
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  Depth of pigment location

  
  
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  Skin location

  
  
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  Skin type

  
  
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  Age of tattoo

  
  
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  Type of laser.

Amateur tattoo ink, usually made with carbon (ash, graphite, India ink), responds best and clears in most patients after 6 to 8 treatments. The laser beam tends to reach and fragment a large quantity of pigment particles with the highest amount located in the epidermis and dermis; only a small amount may be found in deeper structures. Professional multicolored tattoos on the extremities tend to respond slower, requiring more sessions. Older tattoos clear sooner because of the anatomically higher location in the skin layer compared with younger tattoos. Most tattoos treated by the authors clear in 8 to 15 treatments, regardless of the Q-switched lasers used.