Laser Tattoo Removal
Today tattoos are easy and relatively cheap to get, and for most people they are not regarded as an important cultural milestone like they were in early Polynesian culture. As a result, dermatologists often may encounter patients seeking to have these permanent designs removed from their skin. Previously, tattoo removal was attempted using destructive processes such as scarification and cryotherapy and generally resulted in poor cosmetics outcomes. Today, lasers are at the forefront of tattoo removal. Traditional lasers use pulse durations in the nanosecond range, with newer generation lasers in the picosecond range delivering much shorter pulse durations, effectively delivering the same level of energy over less time. It is important to select the correct laser for optimal destruction of various tattoo ink colors (Table).8,9
Controversy persists as to whether tattoo pigment destruction by lasers is caused by thermal or acoustic damage.10 It may be a combination of both, with rapid heating of the particles leading to a local shockwave as the energy collapses.11 The goal of tattoo removal is to create smaller granules of pigment that can be taken up by the patient’s lymphatic system. The largest granule that can be taken up by the lymphatic system is 0.4 μm.10
In laser treatment of any skin condition, the laser energy is delivered in a pulse duration that should be less than the thermal relaxation time of the chromophores (water, melanin, hemoglobin, or tattoo pigment are the main targets within the skin).12 Most tattoo chromophores are 30 nm to 300 nm, with a thermal relaxation time of less than 10 nanoseconds.10,12 As the number of treatments progresses, laser settings should be adjusted for smaller ink particles. Patients should be warned about pain, side effects, and the need for multiple treatments. Common side effects of laser tattoo removal include purpura, pinpoint bleeding, erythema, edema, crusting, and blistering.8
After laser treatment, cytoplasmic water in the cell is converted into steam leading to cavitation of the lysosome, which presents as whitening of the skin. The whitening causes optical scatter, thereby preventing immediate retreatment of the area.11 The R20 laser tattoo removal method discussed by Kossida et al,13 advises practitioners to wait 20 minutes between treatments to allow the air bubbles from the conversion of water to steam to disappear. Kossida et al13 demonstrated more effective removal in tattoos that were treated with this method compared to standard treatment. The recognition that trapped air bubbles delay multiple treatment cycles has led to the experimental use of perfluorodecalin, a fluorocarbon liquid capable of dissolving the air bubbles, for immediate retreatment.14 By dissolving the trapped air and eliminating the white color, multiple treatments can be completed during 1 session.
Risks of Laser Tattoo Removal
It is important to emphasize that there are potential risks associated with laser treatment for tattoo removal, many of which we are only just beginning to understand. Common side effects of laser treatment for tattoo removal include blisters, pain, bleeding, hyperpigmentation, or hypopigmentation; however, there also are rare potential risks. Tattoo ink can paradoxically darken when it contains metals such as titanium or zinc, as often is found in tan or white inks.15 The laser energy causes a shift of the metal from an oxidized to a reduced state, leading to a darker rather than lighter tattoo upon application of the laser. There also have been documented cases of intraprocedural anaphylaxis, delayed urticaria, as well as generalized eczematous reactions.16-18 In these cases, the patients had never experienced any allergic symptoms prior to the laser tattoo removal procedure.
Additionally, patients with active allergy to the pigments used in tattoo ink provide a therapeutic dilemma, as laser treatment may potentially systematize the tattoo ink, leading to a more widespread allergic reaction. A case of a generalized eczematous reaction after carbon dioxide laser therapy in a patient with documented tattoo allergy has been reported.19 More research is needed to fully understand the nature of immediate as well as delayed hypersensitivity reactions associated with laser tattoo removal.
Final Thoughts
With thousands of years of established traditions, it is unlikely that tattooing will go away anytime soon. Fortunately, lasers are providing us with an effective and safe method of removal.