According to a 2016 Harris Poll, 29% of Americans have at least one tattoo, up from 21% in 2012. At the same time, 23% of Americans polled in 2016 regret having their tattoo, which means big business for dermatologists who practice laser tattoo removal.
Dr. Omar A. Ibrahimi
Prior to the theory of selective photothermolysis, tattoo removal mostly consisted of chemical or mechanical abrasion, surgical removal, or using some sort of caustic chemical or thermal destruction of the tattoo, Omar A. Ibrahimi, MD, PhD, said during a virtual course on laser and aesthetic skin therapy. “The earliest lasers prior to refinement by the theory of selective photothermolysis also fell into these categories: just basically crudely removing the skin and trying to get under to where the tattoo is,” said Dr. Ibrahimi, a dermatologist with the Connecticut Skin Institute in Stamford. “These would often heal with horrible scarring.”
Today, clinicians use Q-switched nanosecond and picosecond lasers for tattoo removal, though appropriate wavelengths need to be selected based on the tattoo ink color. Tattoo ink particles average about 0.1 mcm in size, and the thermal relaxation size works out to be about 10 nanoseconds. Black is the most common color dermatologists will treat. “For that, you can typically use a 1064, which has the highest absorption, but you can also use many of the other wavelengths,” he said. “The other colors are less common, followed by red, for which you would use a 532-nm wavelength.”
The clinical endpoint to strive for during tattoo removal is a whitening of the ink. That typically fades after about 20 minutes. “This whitening corresponds to cavitation [the production of gas vacuoles in the cells that were holding the ink],” Dr. Ibrahimi explained during the meeting, which was sponsored by Harvard Medical School, Massachusetts General Hospital, and the Wellman Center for Photomedicine. “These vacuoles are what lead to the whitening when using a high-gigawatt laser in a very short pulse. This causes highly localized heating, cavitation, and cell rupture. We don’t fully understand how tattoos are removed today, but the working models include some of the residual ink coming out through transepidermal elimination, some of it being removed via lymphatics, and some of it being removed by rephagocytosis.”
Alice Pien, MD/Wikimedia/CC BY-SA 4.0
Laser tattoo removal on female using Q-switch laser.
For optimal results, determine if the tattoo is professional, amateur, traumatic, or cosmetic. “That’s going to give you some insight as to what kind of expectations to set for the patient,” he said. “Black ink is often the easiest to remove, while certain colors like white are more challenging. Certain colors are more prone to paradoxical ink darkening, like red or orange, or pink. These can undergo a chemical reaction where they darken. This is something important to discuss with patients in advance.”
Older tattoos “tend to be less hearty” and usually respond better to laser, he continued. Location of the tattoo also plays a role. “I find that tattoos below the knee are very slow to respond. Smaller tattoos will respond faster.”
During the focused medical exam, ask patients about any history of keloid scarring, vitiligo or any dermatologic conditions with a Koebner phenomenon, and rule out a history of parental gold salt administration for arthritis. “During your informed consent you want to make sure you address the expected healing time and the risks such as hyper- and hypopigmentation, blistering, and scarring,” Dr. Ibrahimi said. “You also want to set the expectation that this is not going to be a one and done procedure. Laser tattoo removal takes a series of treatments, often more than what we think – sometimes in the range of 15-20. And you may not get complete clearance. I liken it to breaking it up enough so that if somebody sees it, they won’t be able to recognize what the tattoo is. But you won’t be able to erase it 100%.”
Black, dark blue, and red tattoo colors respond best to laser light. Light blue, green, and purple colors are slower to respond, while yellow and orange colors respond poorly. “Now that we have picosecond lasers, we’re a little better at treating these tougher colors, but I think we still have a lot of room for improvement,” Dr. Ibrahimi said.
Melanin is a competing chromophore, which complicates treatment of tanned individuals and those with darker skin types. “The Q-switched 1064-nm laser is the safest device to use for these patients but it’s not effective for many ink colors,” he said.
Options to keep patients comfortable during the procedure include application of ice or forced chilled air. “You can also use topical anesthetics such as EMLA or liposomal lidocaine cream under occlusion,” he said. “You can also use injectable lidocaine. If you go that route, I recommend a ring block. If you inject right into the tattoo sometimes the ink can get leeched out after treatment. As for spot size, a larger spot size will penetrate deeper, so I try to treat tattoos with the biggest spot size. It also results in less bleeding, less splatter, less side effects, and you get better results.”
Common adverse events from tattoo removal include prolonged erythema, blistering, hyperpigmentation, hypopigmentation, and scarring. Less frequent complications include ink darkening, chrysiasis, and transient immunoreactivity. “We don’t really know what’s in a lot of these ink residues,” Dr. Ibrahimi said. “We know they’re getting mobilized and some of it’s going into the lymphatics. What’s happening with these ink particles? We don’t fully know.”
He also warned against using hair-removal devices to treat a tattoo. “It is the wrong pulse duration,” he said. “You need a picosecond or nanosecond device. You cannot use any other pulse durations, or you will horribly scar your patient.”
In 2012, R. Rox Anderson, MD, director of the Wellman Center for Photomedicine at Massachusetts General Hospital, and colleagues published results of a study that compared a single Q-switched laser treatment pass with four treatment passes separated by 20 minutes. After treating 18 tattoos in 12 adults, they found that the technique, known as the R20 method, was more effective than a single-pass treatment (P < .01). “Subsequent papers have shown that this result isn’t as impressive as initially reported, but I think it’s a method that persists,” Dr. Ibrahimi said.
Another recent advance is use of a topical square silicone patch infused with perfluorodecalin patch during tattoo removal, which has been shown to reduce epidermal whitening. “So, instead of waiting 20 minutes you wait 0 minutes,” he said. “This is called the R0 method,” he added, noting that there are also some secondary benefits to using this patch, including possibly helping as an optical clearing agent for deeper penetration of the laser. “Often after treatment you can see ink on the underside of the patch, which speaks to the transdermal elimination mechanism of action for removal of tattoos.”
As for future directions, Dr. Ibrahimi predicted that there will be better picosecond lasers coming down the pike. He also anticipates that Soliton’s Rapid Acoustic Pulse (RAP) device will make a significant impact in the field. The device was cleared for tattoo removal in 2019 and is being investigated as an option to improve the appearance of cellulite. The manufacturer anticipates that an upgraded RAP device will be cleared for use by the end of the first quarter of 2021.
Dr. Ibrahimi disclosed that he has received research funding and speaker honorarium from Cutera, Lumenis, Lutronic, and Syneron-Candela. He also holds stock in Soliton.