BOOK_CONTENT
From Photodynamic Therapy
C. Fritsch, K. Lang, K.W. Schulte, W. Neuse, T. Ruzicka, P. Lehmann

Summary

The topical cutaneous application of ?-aminolevulinic acid (ALA) induces porphyrin formation in skin, preferentially in tumor tissues. Irradiation of the porphyrin-enriched tumor tissue with Wood's light leads to emission of a typical brick-red fluorescence. This principle may be used as a diagnostic procedure which is termed fluorescence diagnosis with ALA-induced porphyrins (FDAP) or photodynamic diagnosis (PDD). In FDAP, tumors and precancerous lesions of the skin reveal a homogenous intensive fluorescence. Psoriatic lesions also show a strong but non-homogenous porphyrin fluorescence. FDAP in preoperative planning is a valuable method to determine the peripheral borders of a given tumor. The histopathological extensions of the tumors correlate well with the borders detected by the specific fluorescence. The main indications of FDAP are the delineation of clinically ill-defined skin tumors and the control of the efficacy of other tumor therapies.

Photodynamic therapy (PDT) with various photosensitizers has been proven to be highly efficient in the treatment of skin tumors. However, most valid data are available for ALA only, which has been shown to effectively sensitize solar keratoses and superficial basal cell carcinomas with porphyrins. Initial squamous cell carcinomas also show good response to ALA-PDT. Treatment of psoriasis by PDT is a subject under investigation. During the last decade numerous studies on PDT for dermatological diseases have been published, the more important ones are reviewed here.

List of abbreviations

ALA

? -Aminolevulinic acid

BCC

Basal cell carcinoma

BD

Bowen's disease

Copyright European Society for Photobiology 2003 under license agreement with Books24x7

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