Dr. Alai is an actively practicing medical and surgical dermatologist in south Orange County, California. She has been a professor of dermatology and family medicine at the University of California, Irvine since 2000. She is U.S. board-certified in dermatology, a 10-year-certified fellow of the American Academy of Dermatology, and Fellow of the American Society of Mohs Surgery.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Photodynamic therapy (PDT) is a medical treatment that uses a photosensitizing drug (a drug that becomes activated by light exposure) and a light source to activate the applied drug. The result is an activated oxygen molecule that can destroy nearby cells.
Precancerous cells and certain types of cancer cells can be treated this way. The
procedure is easily performed in a physician's office or outpatient setting.
PDT essentially has three steps. First, a light-sensitizing liquid, cream, or
intravenous drug (photosensitizer) is applied or administered. Second, there is
an incubation period of minutes to days. Finally, the target tissue is then
exposed to a specific wavelength of light that then activates the
photosensitizing medication.
Steps:
application of photosensitizer drug
incubation period
light activation
Although first used in the early 1900s, PDT in the modern sense is a fairly
new, evolving science. Current PDT involves a variety of incubation times for
the light-sensitizing drug and a variety of light sources depending on the
target tissue. The basic premise of PDT is selective tissue destruction.
Although the photosensitizer may be absorbed all over by many cells, atypical or
cancerous cells take up more of the drug and retain the drug for a longer duration
than normal tissues.
At present, the primary limitation of available PDT techniques is the depth
of penetration of the light and ability to target cells within at most 1/3 of an
inch (approximately 1 cm) of the light source. Therefore, tumors or atypical
growths must be close to the surface of the skin or treatment surface for PDT to
work.
PDT is currently used in a number of
medical fields including oncology (cancer), dermatology (skin), and cosmetic
surgery.
In oncology, it is FDA approved for non-small cell lung cancer, esophageal
cancer, and precancerous changes of Barrett's esophagus. Its use is also being
further investigated through clinical trials in general oncology for conditions
including cancers of the cervix (mouth of uterus), prostate gland, brain, and
peritoneal cavity (the abdominal space that contains the stomach, liver, and
internal organs).
Levulan stick (photosensitizer medication)
In dermatology, PDT with the photosensitizer Levulan Kerastick® (20% delta-aminolevulinic
acid HCl) is used for the treatment of pre-skin cancers called actinic keratosis
(AK). The initial approval was specifically for normal (non-hyperkeratotic)
actinic keratosis of the face and scalp with a specified 14- to 18-hour drug
incubation time, and 1,000 seconds (16 minutes and 40 seconds) of activation by
a blue light source. PDT is also used for acne, rosacea, skin cancer, sun
damage, cosmetic skin improvement, oily skin, enlarged sebaceous glands,
wrinkles, rejuvenation (anti-aging), warts, hidradenitis suppurativa, psoriasis,
and many other skin conditions. It is not used to remove moles or birthmarks.
Lung cancer kills more men and women than any other form of cancer. Eight out of 10 lung cancers are due
to tobacco smoke. Lung cancers are classified as either small cell or non-small
cell cancers.
Psoriasis is a long-term skin condition that may cause large plaques of red, raised skin, flakes of dry skin, and skin scales. There are several types of psoriasis, including psoriasis vulgaris, guttate psoriasis, inverse psoriasis, and pustular psoriasis. Symptoms vary depending on the type of psoriasis the patient has. Treatment of psoriasis may include creams, lotions, oral medications, injections and infusions of biologics, and light therapy. There is no cure for psoriasis.
Acne is a localized skin inflammation as a result of overactivity of oil glands at the
base of hair follicles. This inflammation, depending on its location, can take the form
of a superficial pustule (contains pus), a pimple, a deeper cyst, congested pores, whiteheads, or blackheads. Treatments vary depending on the severity of the acne.
Skin cancer is the most common form of cancer
in humans. There are three main types of skin cancer; basal cell carcinoma and
squamous cell carcinoma (the nonmelanoma skin cancers), and melanoma.
Common warts are skin growths causes by the human papillomavirus. There are many types of warts, including plantar warts, common hand warts, warts under the nails, mosaic wars, and flat warts. Over-the-counter treatments typically involve the use of salicylic acid products.
Rosacea is a skin disease that causes redness of the forehead, chin, and lower half of the nose. In addition to inflammation of the facial skin, symptoms include dilation of the blood vessels and pimples (acne rosacea) in the middle third of the face. Oral and topical antibiotics are treatments for rosacea. If left untreated, rhinophyma (a disfiguring nose condition) may result.
Esophageal cancer is a disease in which malignant cells form in the esophagus. Risk factors of cancer of the esophagus include smoking, heavy alcohol use, Barrett's esophagus, being male and being over age 60. Severe weight loss, vomiting, hoarseness, coughing up blood, painful swallowing, and pain in the throat or back are symptoms. Treatment depends upon the size, location and staging of the cancer and the health of the patient.
Alcoholism is a disease that includes alcohol craving and continued drinking despite repeated alcohol-related problems, such as losing a job or getting into trouble with the law.
A keloid is a scar that doesn't know when to stop. When the cells keep on reproducing, the result is an overgrown (hypertrophic) scar or a keloid. A keloid looks shiny and is often dome-shaped, ranging in color from slightly pink to red. It feels hard and thick and is always raised above the surrounding skin.
Cancer is a disease caused by an abnormal growth of cells, also called malignancy. It is a group of 100 different diseases, and is not contagious. Cancer can be treated through chemotherapy, a treatment of drugs that destroy cancer cells.
Keratosis pilaris (KP) is a common skin disorder in which small white or red bumps appear around hair follicles on the upper arms, thighs, buttocks, and cheeks. The cause of KP is unknown. There is no cure for keratosis pilaris, and the condition may resolve on its own. Gentle exfoliation, professional manual extraction, chemical peels, and microdermabrasion, along with topical products, are the best treatments for this condition.
Actinic keratoses are rough, scaly patches of skin that are considered precancerous and are due to sun exposure. Prevention is to cut sun exposure and wear sunscreen.
Barrett's esophagus occurs as a complication of chronic gastroesophageal reflux disease (GERD), primarily in white males. GERD refers to the reflux of acidic fluid from the stomach into the esophagus (the swallowing tube), and is classically associated with heartburn.
Smoking is an addiction. More than 430,000 deaths occur each year in the U.S. from smoking related illnesses. Secondhand smoke or "passive smoke" also harm family members, coworkers, and others around smokers. There are a number of techniques available to assist people who want to quit smoking.
Scar formation is a natural part of the healing process after injury. The depth and size of the wound incision and the location of the injury impact the scar's characteristics, but your age, heredity and even sex or ethnicity will affect how your skin reacts.
Age-related macular degeneration (AMD) is a disease that gradually destroys the central vision. In people over 60, AMD is a leading cause of vision loss. Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula, leaking blood and fluid and causing rapid vision loss. In dry AMD, light-sensitive cells slowly break down in the macula, resulting in gradual vision loss. Pain is not associated with either form of AMD.
Wrinkles, whether they be fine line or deep furrows, typically appear on areas of the body that receive a high amount of exposure to the sun. Smoking, light skin type, hairstyle, the way you dress, your occupational and recreational habits, and heredity are all factors that promote wrinkling. Medical treatments for wrinkles include antioxidants, moisturizers, alpha-hydroxy acids, and vitamin A acid. Cosmetic procedures that treat wrinkles include dermabrasion, microdermabrasion, glycolic acid peels, laser resurfacing, Botox, and fillers.
Sunscreens are crucial for sun protection. Sun damage to the skin from exposure to ultraviolet rays is a risk factor for skin cancer and melanoma. To avoid sunburn, people should limit sun exposure during the peak hours of 10 a.m. to 3 p.m., wear protective clothing, and use a sunscreen. People with sensitive skin should use a sunscreen with an SPF of 30 or more.
Keloids can be considered to be "scars that don't know when to stop." A
keloid, sometimes referred to as a keloid scar, is a tough heaped-up scar that
rises quite abruptly above the rest of the skin. It usually has a smooth top and a pink
or purple color. Keloids are irregularly shaped and tend to enlarge progressively. Unlike scars, keloids do not subside over time.
What is the difference between a keloid and a
hypertrophic scar?
After the skin is injured, the healing process usually leaves a flat scar.
Sometimes the scar is hypertrophic, or thickened, but confined to the margin of
the wound. Hypertrophic scars tend to be redder and may subside by themselves (a process which can
take one year or more). Treatment such as injections of cortisone (steroids) can
speed this process.
Keloids, by contrast, may start some time after the injury and extend beyond
the wound site. This tendency to...
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