Lesion selection

Just as important as patient selection is evaluation of the lesion itself. Tattoos can be divided into amateur, professional, cosmetic, medical, and traumatic categories. In amateur tattoos, a steel needle is used to deposit ink, which may be at various depths of the skin, whereas in professional tattoos, a hollow needle is used to inject ink into the dermal layer of skin. Amateur tattoos typically contain pigment of unknown sources such as ash, coal, or India ink (Fig. 3.1). On the other hand, professional tattoo artists often combine ink pigments to achieve novel colors and shading. Cosmetic tattoos using skin-colored tones are important to distinguish, as are medical tattoos such as those used as radiation markers. For traumatic tattoos, it is important to understand the nature of the injury that caused it so as to be aware of the type of material implanted in the skin prior to treatment.

Figure 3.1 Amateur tattoo placed on the hand in a person with Fitzpatrick skin phototype IV.

It is critical when treating pigmented lesions other than tattoos that the lesion itself be evaluated for malignancy. Lasers should not be used for any kind of melanoma, as even with in situ melanoma recurrence rates are very high. Similarly, we recommend against the removal of dysplastic nevi with lasers even though studies have shown no significant increase in carcinogenic markers after laser stimulation of melanocytes.

Patient selection in general

At initial consultation for removal of a pigmented lesion, it is important to take a thorough medical history including a history of allergy to anesthetics (both topical and injectable), current medical conditions, and medications. If a patient is currently taking isotretinoin, laser treatment should be delayed until medication completion as, theoretically, there is a potential for increased scarring and delayed healing. In addition, it is important to note if the patient was ever treated with systemic gold therapy (e.g. rheumatoid arthritis therapy) as this is an absolute contraindication to QS laser treatment since darkening of gold-containing skin is immediate and irreversible. Prophylaxis is appropriate in patients with a history of herpes simplex virus if treating near the trigger point. A history of keloidal scarring and a tendency toward postinflammatory hypo- or hyperpigmentation should also be documented.

Patient selection for tattoo removal

Though tattoos are increasingly popular, they often become a source of personal regret as up to 50% of adults older than 40 with tattoos seek their removal. It is critical that a thorough history of the tattoo be taken prior to deciding upon a treatment plan to establish appropriate patient expectations (Box 3.1). Kirby et al recently published a scale to help practitioners estimate the number of treatment sessions needed for tattoo removal to appropriately guide patients who often enter the laser removal process of their tattoos with uncertainty and misconceptions (Table 3.1). In the scale, numerical values are assigned to six parameters: (1) Fitzpatrick skin phototype, (2) location, (3) color, (4) amount of ink used in the tattoo, (5) scarring or tissue change, and (6) ink layering. The points for each parameter are combined, which results in the approximate number of treatment sessions needed to successfully remove the tattoo, plus or minus 2.5.

In addition to setting a realistic number of treatment sessions for the patient, it is important to alert the patient that some tattoo pigment may still remain and that hypopigmentation may occur in the area, which will leave the outline of the tattoo sans ink. This is especially true in patients with Fitzpatrick skin phototypes IV–VI or in patients with a tan.

The ideal patient for tattoo removal is an untanned patient with type I or II skin and a dark-blue or black tattoo that has been present for at least a year. The older the tattoo, the better is the response to laser treatment as macrophages are already present in the skin and have been at work trying to actively phagocytose the foreign pigment particles. This natural attempt by the body to remove the foreign tattoo ink pigment is the reason why older tattoos are often illegible and have blurry or indistinct margins. Multicolored tattoos, regardless of background skin color, can be very difficult to remove completely with traditional laser systems and treatment should be performed only after the patient fully understands the potential for incomplete fading, pigmentary alterations or scarring. Treatment sessions should be spaced at least 6–8 weeks apart.

Patient selection for benign pigmented lesion removal

As with tattoo removal, it is important to assess the patient presenting for benign lesion removal (Box 3.2). The greater the contrast between background skin and pigmented lesion, the more likely the laser surgeon is to achieve success. At preliminary evaluation, a Wood’s lamp examination may be helpful to assess depth of pigment. Understanding whether the lesion is epidermal, present at the dermoepidermal junction, or dermal will guide laser selection and also allow the physician to set realistic expectations for removal.

Patients should not be tanned when treated and it is important to stress that regular sunscreen use will aid in a durable result (especially in the case of solar lentigines). In patients with darker skin types, we recommend pre-treating pigmented areas with hydroquinone 4% and ceasing treatment 1 week prior to laser therapy. Post-therapy we recommend the use of low potency-topical corticosteroids for 3–4 days to prevent any pigment alteration due to inflammation from the treatment itself. Compared with patients with Fitzpatrick skin phototypes I–III, those with skin photoypes IV–VI have a higher risk of pigmentary alteration and scarring.

Lentigines can be treated most reliably, whereas postinflammatory hyperpigmentation (PIH) and nevi of Ota and Ito present more of a challenge.

Patient preparation

The area to be treated should always be free of any topicals. Removal of pigmented lesions and tattoos can be quite painful for the patient, especially if a large area is to be treated. On the face, we recommend topical anesthetic mixtures that can be compounded at the pharmacy consisting of betacaine, lidocaine, and tetracaine (a typical concentration is 7% of each), or the patient can use a commercial preparation such as LMX-4 or EMLA. A thick layer of this mixture is spread evenly over the treatment area with anesthesia taking place usually within 45 minutes. Penetration of the topical anesthetic can be enhanced by putting the medication under occlusion or applying warm towels over the area. Caution should be exercised if the area is large as topical anesthetics can produce toxicity. Anesthetic should always be completely removed prior to treatment.

Ice is another option, though we recommend ice cubes wrapped in frozen gauze rather than ice packs as the latter tend to not maintain an even temperature. The ice should precede the laser treatment with caution to ensure that no water is left behind. For dermal pigmented lesions on the face, such as nevus of Ota, we sometimes will anesthetize the area with 1% lidocaine.

After informed consent is obtained, pre-treatment photographs are taken. As with any medical procedure, universal precautions should be followed. All QS lasers employ a cone or cylinder placed between the handpiece and the skin to catch any skin debris ejected during laser treatment. Because the cones contain fragments of skin, it is important to use gloves when removing them from the laser after treatment.

Eye safety is also paramount when using lasers. Wavelength-specific protective glasses or goggles must be worn by the patient, provider, and staff at all times during a laser procedure. If the area to be treated is on the eyelid or near the orbit, in the case of the deeply penetrating Nd : YAG 1064 nm laser, internal metal eye shields should be placed for the patient.