Determination of protoporphyrin IX distributions in skin tumors after theapplication of topical aminolevulinic acid,

摘要

Abstract: 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 ALA is 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 ALA via fluorescent imaging. Subjects apply ALA topically 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. !5