Medical Dermatology

PDT Actinic Keratosis

PhotoDynamic Therapy (PDT) for Actinic Keratosis

PhotoDynamic Therapy, or PDT, is a treatment used mainly for the treatment of skin pre-cancers (called Actinic Keratosis) and has FDA approval for the treatment of these rapidly dividing skin pre-cancers. It is also commonly used off-label for facial skin rejuvenation, as well as the treatment of mild to moderate acne.

What is PDT and how does it work?

PDT utilizes Levulan (Aminolevulinic add 20%), a naturally occurring photosensitizing compound, to create a photochemical reaction that selectively destroys cancer cells. Levulan is applied to the skin and subsequently “activated” by specific wavelengths of light. This process of activating Levulan with light is termed Photodynamic Therapy. In the body, Levulanic acid concentrates in skin pre-cancer cells and only becomes active when light of a certain wavelength (in our case, Blue light) is directed onto the area of the pre-cancer. The reaction between the Levulan and the activating light kills the pre-cancer cells.

What is a typical PDT session like?

For the treatment of skin pre-cancers with PDT, there are 3 main stages:

Stage 1:

  • A photosensitizing agent is applied to the treatment area (i.e.-Levulan).
  • The skin may be gently scraped (microdermabrasion) or needled (Collagen P.I.N.) beforehand to increase the amount of the drug absorbed.
  • Wait a certain period of time (1-3 hours, depending on the area being treated) to allow the Levulan to concentrate in the pre-cancer cells

Stage 2:

  • Laser light (Blu-U) or nonlaser light (IPL) is shone directly on the treatment area
  • Treatment lasts around 15 minutes
  • Treatment area is cleansed and aftercare lotion and sunscreen are applied

Stage 3:

  • A sunburn-like reaction usually occurs, which usually heals between 1-6 weeks

What are the side effects of PDT?

Side effects from the PDT are due to the sensitivity of the treated area to light. The photosensitivity of the treatment area to light usually lasts around 2 days (48 hours). Side effects may include burning/stinging sensation, swelling and redness, crusting of the treatment area, itchiness, peeling and blisters, and rarely skin infections.

The treated area should be protected from light for 48 hours. The treated area may blister and ulcerate as the pre-cancer cells die off. This may take several weeks to heal. Scarring is generally minimal, but the loss of pigmentation may occur and can be permanent.


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