The role of
photodynamic therapy (
PDT) in the treatment of in situ
neoplasias and
tumors of the skin is steadily increasing. An intratumoral enriched
photosensitizer and its activation by light are the principles of photodynamic action.
Aminolevulinic acid (ALA) has been shown to be the
drug with most experimental and clinical use in the past. The highest efficacy with most selectivity in topical
PDT is postulated for methyl aminolevulinate or methyl aminooxopenoat (MAL,
MAOP,
Metvix). For solar
keratoses, topical
PDT using MAL is already considered to be the treatment of choice. Epithelial skin
tumors such as
basal cell carcinomas also respond very well, however, a debulking procedure of the exophytic
tumor tissue is an absolute prerequisite to a successful cure. In addition to functioning as a novel therapeutic tool, photodynamic sensitization of
skin cancer cells is increasingly used for fluorescence diagnosis (FD) (also known as photodynamic diagnosis or PDD). The fluorescence of induced
porphyrins is effective in detecting and delineating neoplastic skin areas. Future approaches of FD and
PDT are nontumoral applications, especially
psoriasis, viral-induced diseases, or
acne vulgaris. Topical
PDT is well tolerated and leads to excellent aesthetic results with only minor side effects.