Overview of Laser Treatment of Pigmented Lesions
LASER is an acronym that means Light Amplification by Stimulated Emission of Radiation. In simpler terms, lasers work by using a form of energy called electromagnetic radiation to stimulate particles called electrons. When these electrons return to their normal state from an excited state, they release light energy, which creates a beam that we call a laser. This laser energy travels along a certain path, which we call a wavelength. Wavelengths that we can see with our naked eyes are between 400 and 700 nanometers. However, some lasers operate on wavelengths that are outside this range and are not visible to the human eye.
Lasers have been used in medicine since the 1960s and their uses have expanded over time. One of the ways lasers are used is to target specific colors in the body. Because different lasers operate at different wavelengths, they can be used to treat colored areas of the body like unwanted tattoos, certain skin and mucous membrane conditions, and pigmented skin growths.
When using lasers to treat colored or pigmented areas, it’s important to understand how lasers work, the terms used in laser therapy, and safety procedures. It’s also necessary to understand the pigmented area being treated so that the right kind of laser can be chosen. This article provides information to help understand these concepts.
Anatomy and Physiology of Laser Treatment of Pigmented Lesions
In order for a laser to make changes in our body’s tissues, it must be absorbed by a specific part of a cell known as a chromophore. Important to note is that the depth to which a laser can reach within the body is related to its wavelength – shorter wavelengths can travel farther. Ideally, a laser will only make changes to its target tissue (the chromophore), and will not affect any other tissues in its path.
So what’s a chromophore? This is a component of a cell that can soak up a specific type of laser light. Back in the 1980s, scientists explained this as part of the “selective photothermolysis” principle. Basically, when a chromophore absorbs laser energy, it generates heat, which leads to the destruction of the specific tissue targeted, without damaging the surrounding tissues. Specific types of chromophores include water, hemoglobin, melanin, and deoxyhemoglobin, all of which absorb different wavelengths of light. Hemoglobin, melanin, and deoxyhemoglobin are all visible pigments, but their colors are different.
When lasers produce heat effects, the chromophore within the targeted tissue heats up. Depending on the temperature and how long the tissue is exposed to this heat, it can lead to changes in the tissue such as proteins breaking down, bonds breaking, or internal water boiling. The time it takes for the tissue to cool down to half of its peak temperature is considered when treating lesions, as different tissues cool at different rates. For instance, capillaries (small blood vessels) will take longer to cool than melanosomes (structures within cells that create and store pigment).
In addition to heat effects, lasers can also create what are known as ‘photomechanical’ effects. These occur when tissues experience rapid heating and then rapidly cool down, leading to a shockwave through the tissues which can break down the target tissue. This effect is enhanced when using lasers that pulse rapidly.
One of the key ideas in selective photothermolysis is that an effective laser should largely affect the targeted tissues and not the surrounding ones. A proper understanding of how to measure and describe laser energy is important. Terms to note are ‘joules’, which measure energy; ‘power’, which is energy per second; and ‘watts’, another measure of power. These terms describe the energy coming out of a laser, but don’t account for the intensity of the laser energy’s effects. To measure these effects, we use ‘fluence’, to describe energy density, and ‘irradiance’, which measures the energy delivered to skin or mucosa by continuous laser beams.
Why do People Need Laser Treatment of Pigmented Lesions
When we talk about skin or mouth sores that have a highly dense collection of color-producing elements like hemoglobin, melanin, and deoxyhemoglobin, they usually stand out against the surrounding tissues due to their color. These types of sores are often suitable for treatment with medical lasers. This is because their color contrast allows for precise heat treatment using lasers. If you have an understanding of usual colored lesions, it could help you in identifying when medical laser treatment may be appropriate.
Blood vessel anomalies are a wide group of sores and lumps that often require the attention of several medical specialists. They are divided into vascular tumors and vascular malformations. Several of these anomalies are colored, and they are generally the ones we will discuss here, particularly those related to laser treatment. It’s crucial for the healthcare provider to be able to tell apart the different colored vascular anomalies. They should also be aware of several syndromes which may be discovered during the examination of a vascular lesion.
Infantile hemangiomas, also referred to as strawberry or cherry angiomas, are vascular tumors. These are the most common harmless blood vessel tumors found in children, affecting 4.5% of infants. These sores look like red or reddish-purple raised marks on the skin, and they display rapid cell turnover. While most of these sores are superficial, some are deep or a combination of both. Hemangiomas can be located anywhere, but some particular types are more difficult to treat, depending on their extent and location.
Unlike vascular malformations, infantile hemangiomas do not grow over time. They start as small, flat, light-colored, or red spots at birth. Soon after, they quickly grow. They reach their maximum size around six months of age and then stop growing by one year of age. After this period, they start to shrink and reduce in size over years. While observation is generally appropriate, intervention should happen if a growing hemangioma begins to cause aesthetic or functional issues. In such cases, hemangiomas may bleed and ulcerate, block important structures like the eye or airway, or cause skin and cartilage deformation.
If a patient with a facial segmental hemangioma is encountered, a potential syndrome to consider is the PHACE syndrome. The PHACE syndrome needs to be ruled out by checking a patient for heart abnormalities, posterior brain, and other vascular anomalies, as well as eye irregularities.
Capillary malformations, also known as port-wine stains, are congenital lesions present at birth and they equally affect both boys and girls. They appear as red and lacy sores on the skin and are a result of abnormal connections of skin capillaries. They are usually flat upon appearance but eventually become raised and nodular if untreated. As they darken to purple over time, they are evident in the face and neck. Capillary malformations, when located on the upper face, could be associated with Sturge-Weber syndrome – a disease that impacts the eye and brain blood vessels. Patients with significant capillary malformations should be evaluated for eye and brain findings.
Venous malformations are the most common vascular malformation. They arise from improperly connected, slow-flowing blood vessels, which can easily expand and tend to grow into the surrounding tissues. They typically present at birth, but they are often small and not noticeable in infancy. They often grow and become harder to treat with surgery without significant cosmetic and functional loss. Lasers could be a potential treatment option. Venous malformations are often associated with the Klippel-Trenaunay syndrome, particularly if a patient also has capillary and lymphatic malformations, and limb overgrowth.
Arteriovenous malformations are aggressive vascular malformations that can infiltrate and affect multiple tissues and organs. These lesions are characterized by directly connected arteries and veins, leading to locally destructive shunting. These lesions are soft, warm to the touch, and red or purple. Without early treatment, they can become severely disfiguring or life-threatening. Parkes Weber syndrome is another syndrome associated with arteriovenous malformations
Finally, there’s pyogenic granuloma, also known as a lobular capillary hemangioma. This is a benign fibrovascular lesion associated with the rapid growth of blood vessels. These often appear on the mouth surfaces of the head and neck. They are often aggravated by hormones during pregnancy.
When a Person Should Avoid Laser Treatment of Pigmented Lesions
Pregnancy – Being pregnant does not automatically rule out the possibility of using lasers to treat skin conditions. In the past, doctors used to delay skin laser treatments until after childbirth because they worried it might harm the mother or baby. However, recent research has shown that using lasers to treat skin conditions in pregnant people does not significantly harm the fetus at any stage of pregnancy.
Dark Complexions – Having dark skin does not completely prevent people from having laser treatments. However, there is a risk of more scarring. This is because people with darker skin tones are more likely to have changes in their skin color and scars after such treatments. Specific points for people with dark skin are discussed in the “Complications” section.
Suspicion of Malignancy in Cases of Pigmented Moles – There is a debate about using lasers to treat moles, mainly because the loss of pigment can make it harder to monitor the mole, particularly in situations where there is uncertainty about whether the mole could develop into cancer. Lasers should not be used to treat any suspicious moles that could potentially turn into cancer, and anyone with pigmented moles should have regular long-term check-ups.
Equipment used for Laser Treatment of Pigmented Lesions
The usefulness of lasers comes from their ability to control and organize excited electrons with a constant and powerful energy source. This energy source is placed outside a chamber. Inside this chamber, energy particles, or photons, bounce off mirrors causing more emissions to occur in a uniform pattern along a certain direction. The mirrors are designed in such a way that one of them is partially reflective, letting out an organized, single-color energy beam, or laser beam. A laser beam is collimated, which means it doesn’t spread out much, even over long distances. This helps in pointing and focusing the laser beam towards a specific target. The laser’s energy can not only be aimed with precision but can also be delivered as a continuous beam or a beam with multiple, repeated bursts, called pulses.
Several tools have been designed to help with the delivery of the laser energy. Lasers that aren’t visible are called aiming beams. When these beams are shone on tissues, they guide the laser operator to the laser’s location. The beam could also be manipulated by passing it through a fiber optic cable. These cables help deliver localized laser therapy in hard-to-reach areas.
Cooling devices have proven useful in protecting the outer layer of skin during laser treatments by lessening pain and redness, and helping to prevent blisters, scarring, and changes in skin color. Cooling can happen before, during, and after the laser beam makes contact and can be in contact or non-contact form. Contact cooling involves taking heat away from the skin to the cooling device. This can be active, such as when cooled copper laser tips are used, or passive, like when ice or gels are used. Active contact cooling involves removing heat transferred to the device by thermoelectric components or liquid cooling agents. Passive contact cooling involves removing heat from the skin by transferring it to a cold cooling agent that has heated up. If heat is removed from the skin by evaporation or blowing, like when a coolant is sprayed or cold air is blown on the skin, it is called non-contact cooling.
Who is needed to perform Laser Treatment of Pigmented Lesions?
The team using the laser for treatment is made up of different individuals, including the person doing the actual laser work. Everyone on this team should understand how lasers work and how to use them safely.
The person who uses the laser for treatment should complete a special training course to know how to use the laser safely.
The laser safety officer (LSO) is another important part of the team. This role started in the late 1990s and involves managing and registering the lasers. The LSO is an expert on how to use lasers safely and is in close contact with others in the hospital who will be using the laser.
Preparing for Laser Treatment of Pigmented Lesions
Safety goggles are important for patients and all members of the treatment team when using lasers for medical procedures. Because your eyes can be very sensitive to lasers, it’s important to protect them by wearing these goggles, which should be made specifically for the type of laser being used and fit properly to be effective.
In addition to safety goggles, patients who receive laser treatment near their face or eyes should also use eye shields, which can be made of metal or plastic. These corneal shields, as they’re called, protect the front surface of your eye and should be lubricated before being put in. It’s crucial to wear the shields during treatment as it helps protect your eyes from possible injuries.
During laser therapy, the laser’s heat and destruction of tissue may cause discomfort. One of the benefits of laser therapy for skin conditions is that it’s not as invasive as other procedures. This means the treatment can often be done right in the doctor’s office and doesn’t usually require you to be put to sleep (general anesthesia). Instead, anesthesia is applied topically, or directly to the skin, to numb the area where the laser is used. Certain creams, such as EMLA cream and LMX, can be used for this. Also, local nerve blocks, which are medications that numb a specific area of your body, may be administered.
There are times when a stronger form of anesthesia is needed for pain management during skin laser therapy. This is commonly seen in kids, who may find it difficult to stay still during a painful procedure that takes time. In such situations, the option of general anesthesia, which puts you to sleep, should be discussed with patients, their parents, and anesthesiologists.
Lastly, the treated skin area may need to be cooled, either through a device connected to the laser or by applying ice or ice packs after the procedure. This helps soothe the treated area.
How is Laser Treatment of Pigmented Lesions performed
When it comes to treating red skin lesions such as infantile hemangiomas, blood vessel malformations, and pyogenic granulomas, the flash-pulsed dye laser (FPDL) is often the go-to treatment. Works by targeting a molecule in our blood, oxyhemoglobin – which gives it the red color. This laser is best for surface-level skin lesions as it can reach up to 1.2mm under the skin. The size of the laser beam area and the power can be adjusted based on the patient’s needs. However, it is possible that multiple sessions may be required to fade the redness completely. To avoid damaging the skin cells and prevent blisters or scarring, cooling mechanisms like sprays are commonly used during treatment.
For the treatment of blue skin lesions such as blood vessel malformations, the Neodymium: yttrium aluminum garnet (Nd: YAG) laser is a popular choice. This laser targets deoxyhemoglobin, a molecule in our blood that gives it the blue color. The laser can penetrate deeper into the skin, up to 5-6 mm, and it also has the ability to clot or coagulate the blood. In treatments involving the skin, the Gentle YAG laser is often used. It has a built-in cooling mechanism to protect the skin. The power and treatment time can vary but typically the energy delivered ranges from 130–200 joules per square centimeter. Treatments on mucosal areas i.e., moist areas in the body like the mouth, vary slightly as it doesn’t use a cooling mechanism, and the laser power varies along with the area being treated. Often, you may notice an immediate shrinking of the malformation upon treatment.
Tattoo removal is another area where lasers come into use, with a variety of lasers available such as the fast-pulsed ruby laser and several types of Nd: YAG laser. These lasers work by targeting different colors in the tattoo ink. Despite not knowing the exact way lasers fade tattoos, it’s thought that they break down the pigments via a process involving light, heat, or sound, thereby altering the appearance of the tattoo.
Lasers can also be used for the removal of pigmented nevi, which is a type of mole. Specific lasers target the pigmented parts of the mole to break them down. There are nonspecific lasers available as well, but they work on the water content in skin. Parameters can be adjusted, as with the treatment of blood vessel-related skin disorders. Larger and more power-packed laser beams are used for deeper-lying moles.
Possible Complications of Laser Treatment of Pigmented Lesions
A treatment using the Nd: YAG laser can cause issues with one’s vision, such as bleeding inside the eye and scarring. This is because the laser is absorbed by the dark-coloured part of the eye (the retina). Other lasers can harm the lens and the cornea, which are at the front of your eye, especially when the laser light cannot be seen or it is barely visible. This explains why the use of eye shields and goggles is important when undergoing laser therapy.
Laser treatment on the skin might cause some changes. Redness and bruises are usually temporary after many kinds of laser treatments, but blisters, scar forming, and changes in skin pigmentation are not the normal outcomes. These complications can happen due to heat damage from the laser. So, the doctor should always test a small patch of skin first before proceeding to treat a larger area. It is also important that patients are informed about what kind of changes they can expect with their skin after the surgery. For a specific type of laser treatment (QSRL), the skin may initially turn white and then go back to normal within a few minutes. Swelling and redness should be expected, followed by a crusting and peeling effect on the skin after roughly a week.
Patients having darker skin may react differently to laser treatments. The dark pigment melanin in their skin is widely absorbent of the laser. Thus, people with darker skin can experience heat damage due to the laser. This not only leads to a higher rate of unwanted outcomes but can also reduce the effectiveness of laser treatments aiming to target skin pigmentation. However, people with very dark skin can still have laser treatment, with some special considerations. The key lies in the fact that melanin absorbs less laser energy as the wavelength of the light increases. So, lasers emitting longer wavelengths can penetrate deeper into the skin without being greatly absorbed by the melanin particles in the skin. With this understanding, medics should use lasers with longer wavelengths, when possible, on patients with darker skin tone.
What Else Should I Know About Laser Treatment of Pigmented Lesions?
Laser therapy is a treatment option that’s not very invasive and can be used to address discolored spots or blemishes on the skin or inside the mouth. For certain blood vessel-related growths, lasers have been effectively utilized to manage their growth and prevent potential scarring or limiting of function. Lasers also provide a solution for other colored skin blemishes, which, although potentially not growing or advancing, may be causing you cosmetic distress. For any medical professional treating patients with these types of skin blemishes, lasers are an essential part of the treatment options.
