Determination of protoporphyrin IX distributions in skin tumors after the application of topical aminolevulinic acid

Topical application of aminolevulinic acid ( ALA) is known to lead to enhanced concentrations of protoporphyrin IX(PpIX) in skin tumors versus normal tissue several hours after application. As PpIX is an effective photosensitizer, topical ALAis being used in several clinical trials to treat skin malignancies, with variable success rates to date. As PpIX is highly fluorescent, we have initiated a clinical trial to determine the PpIX distribution in normal and tumor tissue after the application of ALAvia fluorescent imaging. Subjects apply ALAtopically several hours prior to surgical excision of basal cell carcinomas, and the resulting PpIX distributions in normal and tumor tissue are examined on a macroscopic and microscopic scale. This information allows us to determine the exact degree of correlation between PpIX distribution and tumor tissue, and gain insight into the mechanism for the specificity of PpIX for tumor tissue. In addition, we are exploring the possibility of using the PpIX fluorescence as a guide to the excision of skin tumors.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.