Photodynamic therapy (PDT) is a treatment in which a topical cream containing a drug is applied to the skin.
This drug causes the skin to become photosensitive (sensitive to light) to a particular type of light. When this photosensitizer is exposed to a specific wavelength of light, treated cells (mostly cancerous and precancerous cells) are destroyed.
This leads to wound healing mechanisms which lead to tumor destruction and afterwards new tissue build up and skin rejuvenation.