Intralesional photodynamic therapy is a modification of the well-known conventional photodynamic therapy. After the application of a photosensitizing substance, specifically 5-aminolevulinic acid, a light source, usually red, is applied to treat certain skin diseases or other disorders.
The main difference of the intralesional is that both the photosensitizer and the laser light are introduced or “injected” into the lesion, overcoming the main limitation of the conventional technique, which is the ability to penetrate the tissue.
In which cases is it applied?
Photodynamic therapy can be used in many pathologies, both malignant, such as actinic keratosis or cancerization field, superficial tumors and infectious or even inflammatory diseases such as acne.
Specifically, we use the intralesional technique for lesions that occupy deeper parts of the dermis, having experience in the management of hidradenitis suppurativa, basal cell carcinoma, keloids, myxoid cysts, among other pathologies.
How is intralesional photodynamic therapy performed?
Initially, the dermatology specialist injects the substance, lyophilized 5-ALA 2%, inside the lesion and, after a period of absorption, the 630 nm laser light is infiltrated through a glass fiber into the lesion to start irradiating the area. This activates the previously injected substance.
Once activated, it has the capacity to provoke cell death, when we are treating a malignant lesion, or an anti-inflammatory capacity, when we are dealing with inflammatory diseases.
What are the benefits and is there an improvement in most cases?
The initial results are good. Especially in hidradenitis suppurativa, where we have extensive experience and we know that intralesional treatment, combined in most cases with other treatments, is capable of reducing the number of lesions and, to a large extent, controlling pain and restoring quality of life to the patients who suffer from it.
However, it is a very new technique that requires further studies to be fully developed and to achieve a position in the treatment guidelines.
How did you develop the concept, intralesional photodynamic therapy?
Actually, the concept was described by Dr. Manuel Angel Rodriguez Prieto, the intellectual creator of the technique, who together with Intermedic, a Spanish laser company, developed the technique. I later joined the team to continue the development and improvement of the technique applied to patients.
In addition, I did my doctoral thesis in this field using intralesional photodynamic therapy in the treatment of skin cancer.