It is the result of skin being damaged by the sun over many years. Actinic keratosis growths develop due to repeated sun exposure without proper protection and . Steeb T, et al. Cryotherapy is the most common treatment. Are tests needed to confirm the diagnosis? Estoy en riesgo de desarrollar melanoma? If you have an actinic keratosis, commonly called an age spot, your dermatologist may prescribe medication to treat this condition at home. In front of a full-length mirror, inspect the front of your body making sure to look at the front of your neck, chest (including under breasts), legs, and genitals. What are the symptoms of actinic keratosis? Once a month, you should perform a self-exam to look for signs of skin cancer. To be effective, treatment must destroy the AKs. The Skin Cancer Foundation recommends that you: Stephanie Thurrott is a writer who covers mental health, personal growth, wellness, family, food and personal finance, and dabbles in just about any other topic that grabs her attention. Flat to slightly raised patch or bump on the top layer of skin. This kills the affected skin cells. Those with a weak immune system due to chemotherapy, HIV, or an organ transplant are at higher risk. If it is truly just dry it should get better or go away when you put moisturizer on it. Thousands of new, high-quality pictures added every day. American Academy of Dermatology. AskMayoExpert. Although the epidermis appears thick, there is a loss of granular layer with wide gaps between the cells. An actinic keratosis can develop after ultraviolet light from the sun or from indoor tanning damages cells in the skin called keratinocytes, according to the AAD. Fitzpatricks Dermatology in General Medicine. Should you have an AK, an accurate diagnosis and treatment can: Reduce your risk of developing skin cancer, Get rid of an AK, replacing it with new, healthy-looking skin, Help ease symptoms, such as itch, pain, or tenderness. The growths may be gray, pink, red, or the same color as your skin. Similarly, the following conditions are also segregated from the pre-cancerous disorder: Further progression of thedisorder should be stopped, as the lesion is still in the premalignant stage. Topical pharmacotherapy for skin cancer: part I. Pharmacology. J Am Acad Dermatol. Actinic keratosis is usually found on the face, scalp, back of the hands, chest, or places that are often in the sun. Seborrheic keratosis is a type of harmless skin growth that can resemble melanoma. Actinic keratoses are rough , scaly spots that form on sun-damaged skin. However, this seldom occurs in the case of keratotic lesions unless the tumors occupy the deeper layers. It tends to lie flat against the skin of the head and neck, but appears as a bump on arms and hands. Actinic keratosis is a chronic dermatological disorder, which can easily progress to invasive carcinoma of the skin. The light activates the solution, which can destroy the AKs. Commercial tanning lamps as well as beds form the potential source for solar damage besides sunlight. They are essentially very thin skin cancers that have not yet penetrated into deeper tissues. Left untreated, this common skin condition could become cancerous. To be effective, you need to apply the medication as often as your dermatologist recommends. Under a microscope, the epidermal lesion is filled with atypical, pleomorphic keratinocytes in the basal layer, which extends to the upper granular and cornified layers. Affected individuals can use gels containing 0.05% or 0.015% of the substance on trunk, upper extremities, face and scalp. We avoid using tertiary references. These include keratosis pilaris, actinic keratosis, seborrheic keratosis . You can reduce your risk of actinic keratosis by avoiding indoor tanning and limiting your sun exposure. Its effect is milder than 5-FU and causes less inflammation. Further evaluation of the enlarged thick, scaly growths can be done with a normal skin biopsy. They have a rough, scaly texture. skin keratosis. This type of keratosis appears only in areas that are sun-exposed especially the face and neck. They may be oval spots a fraction of an inch across, or form long Christmas tree like . Browse 30 actinic keratosis stock photos and images available, or search for basal cell carcinoma or melanoma to find more great stock photos and pictures. They have a rough, scaly texture. Actinic keratosis is a disorder of epidermal keratinocytes that is induced by ultraviolet (UV) light exposure ().These growths are more common in fair-skinned people and those who are frequently in the sun. Estimates on the risk vary widely by source, but the Skin Cancer Foundation estimates that 5%10% of actinic keratosis lesions become cancerous. Post-application, the skin appears smooth and lesion-free. Laser surgery. Accessed Dec. 23, 2020. An actinic keratosis can develop after ultraviolet light from the sun or from indoor tanning damages cells in the skin called keratinocytes, according to the AAD. Actinic keratosis lesions can appear on any part of your body regularly exposed to sun, but they frequently appear on the face. The procedures that dermatologists use to treat AKs include: Cryosurgery: During cryosurgery, your dermatologist freezes the AK. Accessed Sept. 30, 2020. Your doctor may choose to remove extra tissue around or under the lesion if there are concerns about skin cancer. Actinic keratoses (solar keratoses) Actinic keratoses (also called solar keratoses) are dry scaly patches of skin that have been damaged by the sun. Actinic keratosis is a rough, scaly patch or bump on the skin. Watch TODAY All Day! Actinic keratosis treatment can reduce your risk of cancer and smooth out your facial complexion. A topical medication called 5-fluorouracil may also be used to treat actinic keratoses. Such individuals often complain of sunburns and tans. Have you noticed more changes in the affected skin? The American Academy of Dermatology (AAD) estimates that 40 million people in the U.S. develop actinic keratoses each year. Cryotherapy, also called cryosurgery, is a type of treatment in which the lesion is sprayed with a cryosurgery solution, such as liquid nitrogen. Treatment for AKs can get rid of AKs as well as reduce signs of aging on U.S. Food and Drug Administration. Find out what may be causing the itch and what can bring relief. When you treat at home, you apply medication to your skin as directed. But sometimes an actinic keratosis can be hard to tell apart from skin cancer. You can learn more about how we ensure our content is accurate and current by reading our. Heres what you need to know. These lesions most commonly appear on the:. Eventually, it will cause visible changes to your skin. (2012). skincancer.org/skin-cancer-information/actinic-keratosis/, aad.org/public/diseases/skin-cancer/actinic-keratosis-overview, medicaljournalssweden.se/actadv/article/view/1946, jamanetwork.com/journals/jamadermatology/article-abstract/2782523, jaad.org/article/S0190-9622(19)33290-6/fulltext, 5 Prescription Treatments for Removing Actinic Keratosis at Home, Everything You Need to Know About Nonmelanoma Skin Cancer, Mohs Surgery for Basal Cell Carcinoma: Before and After Treatment. Learn more: Vaccines, Boosters & Additional Doses | Testing | Patient Care | Visitor Guidelines | Coronavirus. When it heals in 1 or 2 weeks, you see new, healthier skin. Neugebauer R, Levandoski KA, et al. The image depicts actinic keratosis, which is the most common precursor of cutaneous invasive squamous cell carcinoma. Seborrheic Keratosis. However, you should have your spots examined by a doctor promptly if you notice any of the following changes: Dont panic if there are cancerous changes. Some manufacturers make specialty clothing with a high sun protection factor (SPF) rating, or you can purchase a special ingredient to be added to your washer that can wash SPF into your clothing. Kang S, et al., eds. We avoid using tertiary references. Sunscreen: How to protect your skin from the sun. A 2020 Swedish study examined the risk of developing certain cancers in the 10-year period after an actinic keratosis first appears. Use a full-length mirror with the added assistance of a hand mirror, when necessary. Actinic keratoses are often painless, and you usually wont notice them unless youre looking in a mirror. Image 1: J Am Acad Dermatol. Aasi SZ, et al. Dermatology, pp.1676-1693. (2021). Jill Biden and Skin Cancer: What to Know About Risks, Screenings, and Surgery, Basal Cell Carcinoma of the Nose: Types, Identification, and Treatment, Skin Cancer: New Moderna Vaccine Shows Promise for Melanoma Treatment, Glycemic Index: What It Is and How to Use It. Actinic keratosis is a common skin condition that frequently appears on the face. Thus, it must be used only in severe cases. Martin G, Swanson N. Clinical findings using ingenol mebutate gel to treat actinic keratoses. J Am Acad Dermatol 2013;68:S39-48. According to the Skin Cancer Foundation, sun exposure is a major factor in the development of actinic keratosis. Learn how to identify skin cancer types and how to prevent and treat them. RF 2CBAP9F . Individuals who are at an increased risk of developing the conditionmust strictly adhere to the following remedial measures: Actinic keratosis has a high rate of malignant transformationand must be immediately diagnosed if the skin spots undergo a sudden change. AK is primarily caused by long-term exposure to sunlight. Chemical peel: This is a medical-grade chemical peel used to destroy the top layers of skin. A dermatologist or other doctor can help diagnose these spots and recommend the best treatment plan for your needs. Your body can heal some of the damage from the suns rays, but the effects of radiation accumulate with every exposure. This is medicine applied to the skin. Avoid applying this ointment to other areas, especially around your eyes or on your lips. Actinic keratosis is a precancerous skin condition that causes patches of rough, patchy lesions. This cream is laden with a non-steroidal anti-inflammatory drug, analogous to ibuprofen. Your dermatologist can do this during an office visit while you remain awake. Our website services, content, and products are for informational purposes only. It is also known by other names like: The condition accounts for 50% of the global population, and is usually common in fair-skinned individuals between the ages of 30 and 60 years. If your clothing tears off the top layer of skin, the lesion may bleed. It should block both ultraviolet A (UVA) and ultraviolet B (UVB) light. Actinic keratoses that develop on the lip are called actinic cheilitis. Normally, it takes 2 days for the 0.05% gel to show positive results, whereas the 0.015% gel requires minimum 3 days for complete treatment of the condition. Even when the medication causes a skin reaction, which indicates that its working, youll need to keep applying the medication. Actinic keratosis lesions are "extremely common," said Dr. Allison Arthur. When she's not writing, look for her out walking her dog or riding her bike in Pennsylvania's Lehigh Valley. An actinic keratosis is a rough and often bumpy patch or lesion that forms on the skin. Burn or sting. This image displays a rather large, inflamed actinic keratosis. It is marked by persistence of the nuclei of keratinocytes as they rise into the stratum corneum of the epidermis. Accessed Sept. 30, 2020. These patches are usually about the size of a small pencil eraser. I see them multiple times a day in my office, said Dr. Allison Arthur, a dermatologist and dermatopathologist at Sand Lake Dermatology Center in Orlando, Florida, and a member of the American Academy of Dermatology. Actinic keratosis usually appears as a patch of dry, scaly skin. Actinic keratosis treatment depends on a few factors, according to the AAD: You can have actinic keratosis treated in a dermatologists office, or you can treat them at home. Many dermatologists recommend seeking treatment for each lesion you develop since theres no surefire way to predict which will become cancerous. Patients first notice actinic keratosis as a scaly, gritty sensation on the face. It feels thick and flaky, almost like a scab that never quite heals. They form when you have actinic keratosis (AK), which is a very common skin condition. After a medical-grade chemical peel, the treated skin will be red, swollen, and sore. What are my treatment options and the pros and cons of each? In other cases, they come and go in the same spot. Over 58 million Americans have actinic keratosis, a skin condition caused by damage from the suns ultraviolet (UV) rays. During a skin biopsy, a small sample of skin is taken for analysis in a lab. High-risk body sites for actinic keratosis in outdoor and indoor workers: A retrospective review. Get the best news, information and inspiration from TODAY, all day long. The deeper region of the epidermis comprises of melanocytes, producing melanin for pigmentation of the skin. Best sunscreens for every age and sensitivity level, American Osteopathic College of Dermatology, How to avoid squamous cell carcinoma this summer, Whats on my skin? the tops and undersides of your arms and hands. People with fair skin are more likely to develop actinic keratoses on sun-exposed areas like the face, arms, hands, back of the neck, and upper chest. The 2020 study mentioned listed how frequently AKs appear on each area of the face: Meanwhile, facial acne will most often erupt in your T-zone, which includes your chin, nose, and forehead. Actinic keratosis is an irregular, skin coloured, red or pigmented papule or plaque and is most often found on a bald scalp, ear, face or back of the hand. They are not life-threatening. They may want to take a skin biopsy of any lesions that look suspicious. Most actinic keratoses can be treated and cured. A few basic tips to prevent actinic keratosis include: Buy quality sunscreen: Look for sunscreen with broad-spectrum UV protection and an SPF of 30 or higher. Diclofenac sodium gel: This medication tends to cause less of a skin reaction than 5-FU, but it can still be very effective. Theres some risk of them progressing to skin cancer, so when we see them, we treat them, Ferris said. Sometimes a biopsy may be done to look for skin cancer. Your dermatologist will explain how to protect your skin so that you can get home. It is atopical medication that functions as an immune stimulator and fights against the viral agents. References One type of skin growth that can look exactly like a seborrheic keratosis is known as actinic keratosis. Erythroderma is not a clinical feature . Mohs surgery is a highly successful outpatient procedure used to treat and cure various forms of skin cancers, including basal cell carcinoma. Healthline Media does not provide medical advice, diagnosis, or treatment. The vast majority of actinic keratosis cases occur when people have long-term exposure to sunlight, especially if they have a light skin tone that is prone to freckling. McGraw Hill Medical, New York, 2008: 1007-15. American Academy of Dermatology. Micali G, Lacarrubba F, et al. Treatment for an actinic keratosis may include: Cryotherapy. This disease is most common in infants and children, but adults may be, Genital human papillomavirus (HPV) infection is a common sexually transmitted infection (STI) caused by human papillomavirus. The skin becomes tender when multiple lesions develop within a single area, causing more discomfort and agony. Removing actinic keratoses helps reduce the risk of skin cancer. We see [actinic keratoses] more frequently on chronically sun-exposed areas like the face, forearms and the backs of the hands, said Dr. Laura Ferris. Actinic keratosis is an erythematous scaly papule or plaque that develops on sun-damaged skin as a result of chronic exposure to ultraviolet radiation, typically in elderly patients with lighter skin types. This treatment freezes the lesion. The skin protrusions are remarkably thick and the base of the horn could be flat or nodular. After cryosurgery, you may see crusting or a blister on your treated skin. In rare cases they may come back. RF 2GN41YD - Lesions and scabs of actinic keratosis or sunspots on sun-damaged skin on a man's wrist. You may need to apply it for 12 to 16 weeks. Heres what you can expect when you see a board-certified dermatologist about AKs. There might be itching or burning in the affected area. Actinic keratoses are pre-cancerous, due to too much sun-exposure over years, which appear as small, scaly lesions that are rough to the touch. https://www.uptodate.com/contents/search. A single lesion generally doesnt pose a major cause for concern, but theres a small chance that an actinic keratosis can become cancerous. https://www.aad.org/media/stats/prevention-and-care/sunscreen-faqs. Tanning beds can also cause actinic keratosis since they emit UV radiation. 2022 WebMD, Inc. All rights reserved. How to spot a precancerous growth on your skin. Seborrheic keratosis and actinic keratosis both cause skin growths, but actinic keratosis may become cancerous. The treatment that is right for you depends on several considerations, including: Your other medical conditions, such as living with a transplanted organ. This image displays numerous areas of sun damage and actinic keratoses. Topical chemotherapy. Some people are more at risk than others, including: People with pale skin, blonde or red hair, and blue, green, or gray eyes, People with darker skin, hair, and eyes who have been exposed to UV rays without protection, People with suppressed immune systems (due to chemotherapy, AIDS, organ transplant, or other causes), People with rare conditions that make the skin very sensitive to UV rays, such as albinism or xeroderma pigmentosum (XP). Then, theyll expose your skin to blue light, which activates the chemical agent to remove the lesions. It tends to lie flat against the skin of the head and neck, but appears as a bump on arms and hands. Quaedvlieg PJF, et al. The lesson learned here is just because a freezing chemical spray can cause a skin lesion to fall off, doesn't mean that there should necessarily be any dramatic changes in appearance (as there often is with actinic keratoses). Mayo Clinic. After you finish treatment, youll see new, healthier skin. 5-FU is not a treatment option for a woman who is pregnant. Actinic keratoses can be removed surgically by cutting, freezing (cryosurgery), or burning. Certain topical treatments such as 5-fluorouracil (Carac, Efudex, Fluoroplex, Tolak) cause inflammation and destruction of the lesions. Your risk increases if you live near the equator, work outdoors, or skip protection like sunscreen and hats. The medications that dermatologists prescribe include the following, which have all been approved by the US. There are several, It's not just the ingredients. Sometimes it looks scabby or wart-like. Carbon dioxide or Er:YAG lasers can repair the sun damaged skin in a short span of time. Actinic keratosis (AK) is the most common precancer that forms on skin damaged by chronic exposure to ultraviolet (UV) rays from the sun and/or indoor tanning. Mayo Clinic; 2020. scalp; backs of the hands; face; ears; back of the forearms Even after treatment for actinic keratosis, your health care provider might suggest that you have your skin checked at least once a year for signs of skin cancer. Your time with your health care provider is limited, so preparing a list of questions will help you make the most of your appointment. In . Limiting time in the sun helps prevent the formation of actinic keratoses. Post-treatment, patients must go for annual check-up to make sure that the problem does not recur or the minute lesions are not growing bigger. Some actinic keratoses can turn into squamous cell skin cancer, so it is important to perform self-examinations often and catch them early. The fluorescent lamps used in these indoor tanning equipments radiate UV rays, which could be detrimental to the skin. They are extremely common. Theyre most often diagnosed in people aged 50 and older whove had a lot of sun exposure, though they can show up in younger people. The forearm is a very common area for sun damage and actinic keratoses. These growths can appear on any part of your body, but they most often show up on the back and chest. However, they can progress to squamous cell carcinoma (SCC), though the likelihood is low. Its best to use a sunscreen with a sun protection factor (SPF) rating of at least 30. These dry skin patches usually appear red, dark, light, pink, or a combination of all these, with a white or yellowish scale on top. In this condition, rough, thick, scaly patches can be observed on sun-exposed areas of skin. Actinic keratosis. Rubbed gently onto the lesions once or twice a day for two to four weeks, 5-FU reportedly produces cure rates of up to 93 percent. Youd apply imiquimod every night for 2 weeks. This natural product is known to cure different types of skin ailments. Thefirst step of the clinical procedure uses an intravenous drug or dye called aminolevulinic acid for sensitizing the skin to light. But unlike dry skin they dont go away with moisturizers.. Use of this site constitutes acceptance of Skinsights terms of service and privacy policy. A low-fat diet (less than 21% calories from fat) has been shown to reduce the incidence of actinic keratoses. In some cases when you call to set up an appointment, you may be referred directly to a specialist in skin diseases (dermatologist). The perfect tummy control bodysuit, a popcorn gadget, more bestsellers starting at $8. Remember: snow and water reflect light to the skin, and clouds still let a lot of light through, so you may still be exposed to ultraviolet light even on cloudy days. McGraw Hill; 2019. https://accessmedicine.mhmedical.com. There is a 7.5% to 10% risk of malignant transformation to squamous cell . In severely chronically sun-damaged individuals, they may also be found on the upper trunk, upper and . Tirbanibulin ointment: This may be an option for treating AKs on your face and scalp. While the rough, gritty scale of actinic keratoses is sometimes easier to feel than see, it can also be very obvious to the naked eye as with this lesion on the forehead. These may grow up to 3-10 mm or several centimeters, resembling warts. You have a higher risk of developing this condition if you: are over age 60. have light-colored skin and blue eyes. If skin cancer develops, the sooner it is found and treated, the better your outcome. These herbal formulations also protect the skin from the damaging effects of UV rays. 16. Skin cancer is the most common cancer in the United States. Photodynamic therapy uses a topical solution and a laser to remove the precancerous lesions. The base of an actinic keratosis may be light or dark, tan, pink, red, or a combination of these. Use a hat with a wide brim. You can learn more about how we ensure our content is accurate and current by reading our. 2013;68(1):98-102. The lesions can be: Benign (not cancerous). It is also called squamous cell skin cancer in situ or Stage 0 . Such individuals often complain of sunburns and tans. All rights reserved. Some people develop a few AKs, which can often be cleared with treatment. Often, a person will have more than one actinic keratosis lesion. A variety of treatment approaches are available for remission of lesions. The sun constantly releases UV radiation, which, like most forms of radiation, isnt great for your skin. In such cases, doctors can slightly stroke, scratch or rub the affected area of the skin to palpate these localized lesions. The most common sites for such thickened scaly growths are the face, specifically on the lips, cheeks, and bridge of the nose and ears. Keep every appointment. http://en.wikipedia.org/wiki/Actinic_keratosis, http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001830/, http://www.mayoclinic.com/health/actinic-keratosis/DS00568, http://www.skincancer.org/skin-cancer-information/actinic-keratosis. Some of these are: The method involves application of extreme cold in the form of liquid nitrogen,solid carbon dioxide, or argon to destroy the abnormal lesions. If you find a change on your skin that could be an actinic keratosis, protect your health by seeing a board-certified dermatologist. This causes the textural details that often distinguish the growths. Prolonged and intense sun exposure acts as a contributing factor in causing the condition. JAMA. ", If you suspect you might have actinic keratosis, see your dermatologist. Causes of actinic keratosis. Keratosis On The Scalp. As the treated skin heals, youll see new, healthier skin. See pictures and learn about causes, prevention, diagnosis, treatment, and, A new mRNA skin cancer vaccine being developed by Moderna showed promise in a phase 2 clinical trial in treating late-stage melanoma, The glycemic index (GI) is a value used to measure how much a specific food increases your blood sugar levels. Accessed Sept. 30, 2020. With your arms raised, inspect both sides of your body making sure to examine your underarms. If 12 to 16 weeks is too long, you may be able to use the medication a bit differently. This image displays actinic keratosis of the legs. They . Guorgis G, et al. Emily Swaim is a freelance health writer and editor who specializes in psychology. We are vaccinating all eligible patients. The advantage of using a medication to treat your AKs is that the medication can treat many AKs, including the ones you cannot see yet. DOI: Here are some pictures of SCC and what changes to look out for. This means that even short-term exposure to sun on a regular basis can build up over a lifetime and increase the risk of actinic keratoses. Afterward, youll be treated with either a blue or red light. The sun-exposed areas of the face, scalp (where balding), ears, neck, forearms, and backs of the hands are most commonly affected with actinic keratoses, but any skin area frequently exposed to sun can be involved. Clinical Information and Differential Diagnosis of Actinic Keratosis (Solar Keratosis), Mild one or two spots, not thick or hard, Severe numerous or thick, hard, or bleeding spots. This is known as a skin biopsy. Wear hats and shirts with long sleeves when youre in bright sunlight. For an optimal experience visit our site on another browser. As your skin heals, the damaged cells slough off, allowing new skin to appear. The goal is to get the AK to fall off after a few days. Those who have had a lot of sun exposure in their youth are at a high risk as well. Sometimes, it takes on a red color. Do you know which one? The Food and Drug Administration (FDA) has approved the following medications: Other treatments that may help address widespread actinic keratosis include photodynamic therapy specifically, blue light therapy and chemical peels. You can often complete treatment in 1 or 2 office visits. Whats the Difference Between Seborrheic Keratosis and Actinic Keratosis? But there's a small chance they could become skin cancer, so it's important to avoid further damage to your skin. Skin exams are recommended for patients who are frail and may find it hard to tolerate treatment. Seborrheic keratoses are often mistaken as skin cancer. have a tendency to . Epidemiology, natural history, and diagnosis of actinic keratosis. Gavish is an award-winning freelance medical and health writer and editor with 15 years of experience. Find more COVID-19 testing locations on Maryland.gov. Nov. 25, 2020. Make a donation. 2005-2023 Healthline Media a Red Ventures Company. The size of actinic keratosis varies from tiny to an inch or more in diameter. With your back to the mirror and holding a hand mirror, inspect the back of your body, including the back of your neck, shoulders, legs, and buttocks. These are done to remove or destroy the lesion. You can take steps to prevent actinic keratoses from appearing in the first place. Although people with light skin are more likely to have actinic keratosis, these spots can appear on people with any skin tone. Lebwohl M. Actinic keratosis. Image Source: 2007 Interactive Medical Media LLC. It works by removing the surface layer of the skin. It can help treat skin cancer, prostate cancer, and more. Some AKs look and feel inflamed. 9th ed. After a brief incubation period, the target skin is exposed to light from a laser or other source. If you have several actinic keratoses, your health care provider might prescribe a medicated cream or gel to remove them, such as fluorouracil (Carac, Efudex others), imiquimod (Aldara, Zyclara) or diclofenac. Inspect the tops and bottoms of your feet, the area between your toes, and toenails. This can be treated with cryosurgery or certain ointments. They typically feel like sandpaper. Well show you what it looks like, and explain. People with fair skin are more likely to develop actinic keratoses on sun-exposed areas like the face, arms, hands, back of the neck, and upper chest. Keratosis exists in a variety of types that are categorized by different degrees of severity. This medication can harm an unborn baby. With photodynamic therapy, your dermatologist will spread a chemical agent across the actinic keratoses on your face. Photodynamic therapy uses a light-sensitizing compound that preferentially accumulates in actinic keratosis cells where the appropriate wavelength of light can activate the therapy.