Is photodynamic therapy a solution for keloid?

Keloid is a common skin condition, especially in people of Asian and African decent. The treatment of keloid is still unsatisfactory. Photodynamic therapy (PDT) is a novel treatment for this condition, but is widely used in treating certain skin pre-malignant and malignant lesions due to its high efficiency and safety. Another aspect of PDT is its scarless (or minimal scarring) wound healing after treatment despite the fact that it causes skin inflammation. There are a few independent reports that indicate 5-aminolevulinic acid (ALA) or methylaminolevulinate (MAL)-PDT may be effective in keloid and hypertrophic scars. The mechanism is largely unknown. PDT may exert these effects by acting on keratinocytes and fibroblasts or directly on collagen/extracellular matrix (ECM) in keloid tissues, by inducing keloid fibroblast apoptosis/necrosis, modulating growth factor and cytokine expression, reducing collagen/ECM synthesis and causing degeneration of formed collagen/ECM. These potential mechanisms and the scope for topical PDT of keloids are considered in this article.