Photodynamic Diagnosis and Therapy in Dermatology

Abstract

The topical application of δ-aminolevulinic acid (ALA) induces porphyrin formation in the skin, preferentially in tumor tissues. Irradiation of the porphyrin-enriched tumor tissue with Wood’s light leads to emission of a brick-red fluorescence. This principle may be used as a diagnostic procedure which may be termed photodynamic diagnosis (PDD). In ALA-PDD, tumors and precancerous lesions of the skin reveal a homogeneous, intensive red fluorescence. Psoriatic lesions also show a strong but inhomogeneous porphyrin fluorescence. ALA-induced porphyrin fluorescence 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 tumor-specific fluorescence. The main indications of PDD are the delineation of clinically ill-defined skin tumors and the control of the efficacy of other tumor therapies. Photodynamic therapy (PDT) utilizes exogenously applied or endogenously formed photosensitizers and their activation by light to induce cell death via formation of singlet oxygen and other free radicals. PDT is highly efficient in the treatment of solar keratoses and superficial basal cell carcinomas. Initial squamous cell carcinomas also show good response to ALA-PDT. During the last decade, numerous studies on PDT for dermatologic diseases were published, the more important ones are reviewed here.

Treatment of Cutaneous Leishmaniasis With Photodynamic Therapy

“…6 Recently, interest has centered around the antimicrobial activities of PDT. Propionibacterium acnes produces porphyrins that absorb light in the near-UV-and blue-light spectrum, and exogenous ALA that accumulates in the pilosebaceous units has been used successfully in the treatment of acne vulgaris.…”

Photodynamic Diagnosis with 5–Aminolevulinic Acid in the Treatment of Secondary Urethral Tumors: First in vitro and in vivo Results

“…Its use in urology has just recently been extended to the upper urinary tract and kidney by oral intake of the sensitizer [14, 15]. Topical application including non–urological forms of application, such as for dermatology or gynecology [16, 17, 18, 19], was shown to be feasible and safe.…”

5-Aminolevulinic-acid-mediated Photodynamic Diagnosis Enhances the Detection of Peritoneal Metastases in Biliary Tract Cancer in Mice

“…In clinical trials, Stummer et al (9) first demonstrated the use of photodynamic diagnosis (PDD) using 5-ALA to diagnose malignant glioma, intraoperatively. Subsequently, 5-ALA PDD use has been evaluated for various cancers and brain surgery (8,10,11). However, biliary tract cancer is rare.…”