A commentary on the role of skin temperature on the effectiveness of ALA-PDT in Dermatology.

The review of several studies indicates clearly that improving ALA-PDT of skin lesions might be achieved by elevating the skin temperature during the ALA application. Several mechanisms could be responsible: a better ALA uptake and/or an higher PpIX production into cells due to an improved enzymatic process, mainly due to the increased activity of ferrochelatase. Vasodilatation of skin vessels could also increase the oxygen supply and consequently enhances the generation of singlet oxygen, and other cytotoxic species. Different techniques can be used to perform an elevation of skin temperature: IRA, heating blanket, etc. At last, skin heating could increase the penetration (depth) of ALA into the skin, which thereby may increase PpIX production (in deeper layers) in the skin. This could represent an interesting approach to improving ALA-PDT of nodular BCC and other skin lesions.