Laser choices grow increasingly complex
Aspen, Colo. — Successful laser treatment of pigmented lesions and tattoos requires choosing the right tool for the job, an expert says.
Virtually any laser can target melanin, says George Hruza, M.D., a dermatologist in private practice in Chesterfield, Mo. “But some lasers work better than others.”
In particular, he says that targeting melanosomes requires pulse widths under one µs, the thermal relaxation time of the dermis.
“On the other hand, targeting epidermal lesions requires pulse widths under 1 ms,” because such pulses cause epidermal necrosis, he says.
Q-switched gets results
The standard of care for pigmented lesions and tattoos generally involves Q-switched lasers, whether ruby, alexandrite or Nd:YAG, Dr. Hruza adds. “They all work quite well.” Long-pulsed lasers also work for these indications, he says, but with a smaller safety margin. Somewhat similarly, he says that intense pulsed light (IPL) devices can lighten pigmented lesions. “However, I don’t believe these are the best way to treat individual lesions,” he says.
Ablative lasers remove pigment by removing the epidermis, Dr. Hruza says. Regarding fractional ablative lasers, he says, “I use them primarily for area treatments,” to remove hundreds of lesions at once. But for individual lesions, he prefers Q-switched lasers. “They allow for very specific targeting — one or two treatments and you’re done.”
Regarding specific clinical entities, Dr. Hruza says he would not treat a benign melanocytic hyperplasia with a laser without first confirming via biopsy that it is not lentigo maligna (LM). For café au lait macules, Dr. Hruza says, several treatments with a laser such as the Q-switched Nd:YAG or Q-switched ruby laser can lighten them quite effectively.
“But at least 50 percent of the time, they return,” Dr. Hruza says.
For dermal pigmented lesions such as nevi of Ota, he primarily uses Q-switched lasers with nanosecond pulsing, such as the 1,064 nm and occasionally the 532 nm Q-switched laser. For melanocytic dermal lesions, Dr. Hruza advises waiting four months between treatments to see the full results of the preceding session.
Additionally, “One can use a long-pulsed laser for compound nevi, provided one confirms that they are benign. Be somewhat careful,” he says, because these treatments may leave patients with depressed scars created by bulk heating of the treatment area.
Minocycline pigmentation also responds to treatment with any Q-switched laser, Dr. Hruza says. However, “The treatment hurts quite a bit because there’s so much chromophore” to absorb the laser energy. Imipramine pigmentation also responds well to virtually any Q-switched laser (Atkin DH, Fitzpatrick RE. J Am Acad Dermatol. 2000;43(1 Pt 1):77-80).
Conversely, Dr. Hruza says he has never achieved long-term success in treating Becker’s nevus with Q-switched or any other lasers. Even if one adds a nonablative fractionated laser, he says, “There’s a dermal component that activates the pigmentation. So you don’t really get rid of the whole problem.”
As for melasma, “I still don’t believe anything works very well.” For this indication, Dr. Hruza says he prefers the Q-switched Nd:YAG laser operating at low fluences, rather than fractionated lasers. Even with the former, however, results are only temporary, he says. For freckles, Dr. Hruza generally treats the entire area with a fractional thulium laser, then has patients return for retreatment every year or so.
For tattoo treatments, Dr. Hruza says, many studies delineate which lasers work for which ink colors. He suggests, however, that simply choosing the opposite color (on a color wheel) of the one being treated usually suffices. For example, green lasers work for red tattoos, and vice versa, he says. Moreover, most tattoos require multiple lasers, or at least multiple wavelengths.
In his practice, tattoo treatments begin conservatively and increase fluence levels with each treatment. Conversely, “When treating very dense, dark pigment, we must be more careful because patients can get bulk heating, which can lead to scarring.” Dr. Hruza generally spaces tattoo treatments at least six to eight weeks apart — and at least three months apart on the legs.
“It’s important to give the body time to remove the particles of (treated) ink, and patients get more bang for the buck,” he says.
On a practical note, Dr. Hruza says he never predicts how many tattoo or pigment treatments a patient will need. And he prices all laser treatments individually because selling packages would create the impression that the number of treatments in the recommended package would provide complete clearance.
In his experience, Dr. Hruza says, facial tattoos may require two to four treatments, versus up to 20 or more for tattoos on the legs. “For multicolored tattoos,” he adds, “I generally try to talk patients out of treatment because treating every single color is very difficult.”
Disclosures: Dr. Hruza reports no relevant financial interests.
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